Final Dissertation
Develop automatic measure
system for basic measurements of semiconductors
Author:
Arturo Campos
Supervisor:
Dr. Andras Feher
A dissertation submitted in fulfilment of the requirements
for the degree of Advanced Telecommunications Engenieering
Quesada Pereira, by his constant dedication, willingness and patience,
to my colleagues and friends, for making unforgettable years of University,
to my girlfriend for her love and understanding, and my family for their support when I needed it most.
i
Contents ii
List of Figures iv
List of Tables vi
1 Introduction to the thesis topic 1
2 Background information and theory 2
2.1 Semiconductor Theory . . . 2
2.1.1 Diodes . . . 5
2.1.1.1 PN junction diode . . . 7
2.1.1.2 Light Emitting Diode (LED) . . . 8
2.1.2 Transistors. . . 10
2.1.2.1 Bipolar Transistor . . . 11
2.1.2.2 Unipolar Transistor. . . 16
2.1.3 Thyristors . . . 17
2.2 Devices . . . 21
2.2.1 Power Supply HMC8043 . . . 21
2.2.1.1 Working Manual . . . 22
2.2.1.2 Programming Manual . . . 25
2.2.2 Digital Multimeter HMC8012 . . . 26
2.2.2.1 Working Manual . . . 27
2.2.2.2 Programming Manual . . . 28
2.2.3 Others . . . 29
2.3 Software . . . 29
2.3.1 Python. . . 30
2.3.2 National Instruments VISA . . . 32
3 Setups and Test Reports 34 3.1 Devices’ connection . . . 34
3.2 Leds and Diodes . . . 34
3.2.1 Setup . . . 34 ii
3.2.1.1 Circuits . . . 34
3.2.1.2 Program . . . 40
3.2.2 Results. . . 42
3.3 Transistors. . . 47
3.3.1 Setup . . . 47
3.3.1.1 Circuits . . . 48
3.3.1.2 Program . . . 50
3.3.2 Results. . . 52
3.4 Thyristors . . . 55
3.4.1 Setup . . . 55
3.4.1.1 Circuits . . . 56
3.4.1.2 Program . . . 58
3.4.2 Results. . . 58
4 Conclusion and future directions 61
A Programing Code 62
Bibliography 68
Bibliography 68
2.1 Applications for the Semiconductors in the society . . . 5
2.2 PN junction diode . . . 7
2.3 Diode characteristic . . . 8
2.4 LED Schematic . . . 9
2.5 Transistor Schematic . . . 11
2.6 Transistor configuration . . . 12
2.7 Transistor Input characteristics . . . 13
2.8 Transistor Output characteristics . . . 14
2.9 Thyristor Schematic . . . 18
2.10 Thyristor graph . . . 20
2.11 Thyristor’s types . . . 21
2.12 HMC8043 front panel . . . 23
2.13 HMC8043 back panel . . . 23
2.14 HMC8043 interface . . . 24
2.15 HMC8012 front panel . . . 27
2.16 HMC8012 back panel . . . 28
2.17 Ethernet rj45 cable . . . 29
2.18 Switch device . . . 29
2.19 Python(x,y) download . . . 30
2.20 Python(x,y) interface . . . 31
2.21 Spyder interface . . . 31
2.22 NI-VISA download . . . 32
2.23 NI-VISA Interface. . . 32
2.24 NI-VISA Trace . . . 33
3.1 Theoretical LED circuit . . . 35
3.2 LED circuit . . . 36
3.3 Ge diode . . . 36
3.4 Red LED . . . 37
3.5 Clear LED . . . 37
3.6 Power Diode Rectifier. . . 37
3.7 Half Wave Rectifier . . . 38
3.8 Half-wave Rectifier with Smoothing Capacitor . . . 38
3.9 Diode Bridge Rectifier . . . 39
3.10 Full-wave Rectifier with Smoothing Capacitor . . . 40
iv
3.11 Diode flowchart . . . 41
3.12 Files folder. . . 42
3.13 Characteristics of Ge diode . . . 43
3.14 Characteristics of red LED . . . 45
3.15 Characteristics of clear LED . . . 47
3.16 OC1045 datasheet. . . 47
3.17 Theoretical transistor circuit . . . 48
3.18 Transistor circuit I . . . 49
3.19 Transistor circuit II . . . 50
3.20 Transistor flowchart . . . 51
3.21 Input characteristics of bipolar transistor . . . 53
3.22 Output characteristics of bipolar transistor . . . 53
3.23 P01264A datasheet I . . . 55
3.24 P01264A datasheet II . . . 56
3.25 Theoretical thyristor circuit . . . 57
3.26 Thyristor circuit. . . 57
3.27 Thyristor flowchart . . . 58
3.28 Thyristor characteristics . . . 60
3.1 Characteristics of Ge diode. . . 43
3.2 Characteristics of red LED . . . 44
3.3 Characteristics of clear LED . . . 46
3.4 Input characteristics of bipolar transistor . . . 52
3.5 Output characteristics of bipolar transistor . . . 54
3.6 Thyristor characteristics . . . 59
vi
Introduction to the thesis topic
The project will consist of be the development of a practical handbook of semicon- ductor circuits with the novelty of implementing automation of processes through Python.
First, a review of theoretical foundations of the different semiconductors will be carried out.
Moreover, a small handbook explaining the employed devices will be developed, as well as an introduction to the programming language used and how to get it.
Finally, the processes developed in basic circuits of semiconductors used is to check and it raised some development by students.
This project is expandable and can be developed in the future for other semicon- ductors and/or extend automated processes.
1
Background information and theory
2.1 Semiconductor Theory
A semiconductor component is defined as a solid material or liquid can conduct electricity better than an insulator, but worse than a metal.
The electrical conductivity, which is the ability to conduct electric current when applying a potential difference, is one of the most important physical properties.
Certain metals, such as copper, silver and aluminum are excellent conductors. On the other hand, certain insulation such as diamond or glass is very poor conductors.
At very low temperatures, pure semiconductors behave as insulation. Subjected to high temperatures, mixed with impurities or in the presence of light, the con- ductivity of semiconductors can increase dramatically and reach levels close to the metals. The properties of semiconductors are studied in the physics of the solid state.
The electrical properties of a semiconductor material are determined by its atomic structure. In a pure crystal of Germanium or silicon, the atoms are joined together at disposal periodically, forming a diamond cubic grid perfectly regular. Each Crystal atom has four electrons from valencia, each of which interacts with the neighboring Atom electron forming a covalent bond. Having no electrons free movement, at low temperatures and in pure crystalline state, the material acts as an insulator.
2
Germanium or silicon crystals contain small amounts of impurities that lead to electricity, even at low temperatures. The impurities have two effects within the Crystal. The impurities of phosphorus, antimony or arsenic are called donor im- purities because they provide an excess of electrons. This group of elements has five electrons in valencia, of which only four established links with germanium or silicon atoms. Therefore, when an electric field is applied, donor impurities remaining electrons are free to move through the crystal material. Conversely, im- purities of gallium and Indium have only three valencia electrons, i.e., one missing to complete the structure of interatomic bonds with Crystal. These impurities are known as receiving impurities, because they accept electrons of neighboring atoms. At the same time, consequential, or hollow, deficiencies in the structure of neighbouring atoms are filled with other electrons and so on. These holes behave like positive charges, as if they moved away from the electrons when a voltage is applied to them.
Semiconductors of types n and p: a crystal of Germanium or silicon containing donor impurity atoms is called semiconductor negative, or type n, to indicate the presence of an excess of negatively charged electrons. The use of a receiving impurity will produce a positive semiconductor, or p-type, named for the presence of positively charged holes. You can prepare a simple Crystal that contains two regions, a type and another type p, introducing donor and recipient impurities in Germanium or silicon melted in a crucible in various stages of formation of the Crystal. The resulting Crystal will present two different materials type regions n and p-type. The strip of contact between the two areas is known as union pn. Such union can be produced also by placing a portion of material of donor impurity on the surface of a Crystal p-type or a portion of receiving impurity on a Crystal n-type material, and applying heat to spread the impurity atoms through the outer layer. By applying a voltage from the outside, the pn union acts as a rectifier, allowing current to flow in only one direction. If the p-type region is connected to the positive terminal of a battery and the n to the negative terminal- type region, will flow a strong current through the material throughout the union.
If the battery is connected backwards, current will not flow.
The characteristics of PN unions have their main application in the manufacture of diodes, which are devices with a PN union whose main function is the driving current flow when the polarization is direct and lock it when it is in reverse.
Also the avalanche (maximum reverse polarization voltage) voltage can be used to manufacture special diodes zener, whose characteristic is that reverse polarization voltage remains constant to vary the intensity of the cathode to the anode in a certain value of manufacturing, this peculiarity is useful to build voltage stabilisers- denominated.
Most popular transistors are two junctions in series which may be PNP or NPN type. Its quality is one much higher intensity flowing flowing a stream from the central union P to the union type N (example of type NPN), flows much higher since the other union intensity N toward the previous N in proportion to the intensity that we insert. With this property, we can build amps voltage or current.
Modern society is increasingly dependent upon electrical appliances for comfort, transportation, and healthcare, motivating great advances in power generation, power distribution and power management technologies. These advancements owe their allegiance to enhancements in the performance of power devices that regu- late the flow of electricity. After the displacement of vacuum tubes by solid state devices in the 1950s, the industry relied upon silicon bipolar devices, such as bipo- lar power transistors and thyristors. Although the ratings of these devices grew rapidly to serve an ever broader system need, their fundamental limitations in terms of the cumbersome control and protection circuitry led to bulky and costly solutions. The advent of MOS technology for digital electronics enabled the cre- ation of a new class of devices in the 1970s for power switching applications as well.
These silicon power MOSFETs have found extensive use in high frequency applica- tions with relatively low operating voltages (below 100 V). The merger of MOS and bipolar physics enabled the creation of yet another class of devices in the 1980s.
The most successful innovation in this class of devices has been the insulated gate bipolar transistor (IGBT). The high power density, simple interface, and rugged- ness of the IGBT have made it the technology of choice for all medium and high power applications, with perhaps the exception of high voltage DC transmission systems. Even the last remaining bastion for the conventional power thyristors is threatened by the incorporation of MOS-gated structures. Power devices are required for systems that operate over a broad spectrum of power levels and fre- quencies. In Fig. 1.1, the applications for power devices are shown as a function of operating frequency. High power systems, such as HVDC power distribution and locomotive drives, requiring the control of megawatts of power operate at rel- atively low frequencies. As the operating frequency increases, the power ratings
decrease for the devices, with typical microwave devices handling about 100 W.
All these applications are served by silicon devices. Thyristors are favored for the low frequency, high power applications, IGBTs for the medium frequency and power applications, and power MOSFETs for the high frequency applications.
Figure 2.1: Applications for the Semiconductors in the society
2.1.1 Diodes
Diode, electronic component that allows the passage of current in one direction only. Used in the current electronics diodes are manufactured with semiconductor diodes. The simplest, the point of contact of Germanium diode, was created in the early days of radio. In modern (or silicon) germanium diodes, cable and a tiny glass plate are mounted within a small glass tube and connected to two wires which are welded to the ends of the tube.
Union diodes consist of a union of two different kinds of semiconductor material.
The Zener diode is a special model of the diode’s union, which uses silicon, in which tension parallel to the union is independent of the current that flows through it.
Due to this characteristic, the Zener diodes are used as voltage regulators. On the other hand, in the (acronym for Light-Emitting Diode LED) light emitting
diodes, a voltage applied to the semiconductor union resulting in the emission of light energy. LEDs are used in panels numerical electronic digital watches and pocket calculators.
To resolve problems relating to the diodes at present three approaches are used:
The first approach is the ideal diode, believes that the diode does not have voltage when driving in direction drop-positive, so this first approach would consider that the diode is shorted in a positive sense. On the other hand, the ideal diode behaves like an open circuit when its polarization is reverse.
In the second approach, we consider that the diode has a voltage drop when it leads in direct polarization. This voltage drop is set to 0.7 V for Silicon diode, making that the second approach be represented as a switch in series with a source of 0.7 V.
The third approach closer the curve of the diode to the real, which is a curve, not a straight, and it fit a resistor in series with the supply of 0.7 V.
Vd = 0.7 + IdR (2.1)
Still, in the above equation, R the third approach (usually very small) resistance, and Id the current polarization of the diode. The most widely used is the second approach.
Junction diodes and the zener have design features that differentiate them from others. Its size, in many cases, does not exceed that of a layer or film 1/4W resistance and although his body is cylindrical, is smaller length and diameter than the heating elements. Although there is a wide variety of types, only some special differ from their appearance. Not so with the size, because it is a function of the power that can be dissipated. It is characteristic to be an aillo in the body that indicates the cathode. For those whose concrete type is designated by a series of letters and numbers, the cathode is marked by a ring on the body, next to this terminal. Others use codes of colours, and in them cathode corresponds to the terminal nearest to the thicker color. There are manufacturers which marked with the letter ”K” cathode or anode with the ”a”. Tip of Germanium diodes are often encapsulated in glass. Regarding the LEDs are encapsulated in resins of different
colors, depending on wavelength with which issue. These diode anode is longer than the cathode, and potting face next to the cathode is usually flat.
A practical way to determine the cathode consists of applying a multimeter ohm- meter between its terminals mode. If the test terminal applies anode to cathode, are readings of the order of 20-30 Ω. If the terminals are reversed, these readings are on the order of 200-300 KΩ for the Ge, and several MΩ for the Si. If you are using the diode test mode with the multi-tester, we obtain the value of the volt- age of the device elbow. This managed to identify the two terminals (anode and cathode), and material which is made (0.5-0.7 V for the Si, 0.2-0.4 for germanium and 1.2-1.5 for the majority of the LED.)
2.1.1.1 PN junction diode
The term PN junction diode is normally reserved for what may be called the basic form of diode, although in reality the term applies to virtually any form of semiconductor diode.
Figure 2.2: PN junction diode
These diodes rely on the properties of semiconductors for their operation.
Using semiconductor technology, the PN junction diode gains its name from the fact that it is formed from a semiconductor PN junction and by its nature it only allows current to flow in one direction. However the PN junction diode also has other properties that can be used in many other applications. These range from light emission to light detection and variable capacitance to voltage regulation.
The theory behind semiconductor diodes uses the basic semiconductor ideas and applies them to a junction between the two types of semiconductor, p-type where the charge carriers are formed by holes and n-type where the charge carriers are electrons.
The basic form of PN junction finds many uses in electronics circuits. The stan- dard PN junction diodes are available in a variety of forms. They are mainly manufactured from silicon, although germanium diodes are also available. PN junction diodes can also be manufactured from other semiconductor materials, but these are generally specialised diodes used for particular applications.
The PN junction has the characteristic curve shown below. It can be seen that current is blocked in the reverse direction, although at some stage it will break down. In the forward direction current flows once the ’turn-on’ voltage has been exceeded. Typically this is 0.6 to 0.7 volts for silicon diodes and 0.3 to 0.4 volts for germanium. Some diodes such as Schottky diodes or those using different materials, etc will have different characteristics and turn-on voltages.
Figure 2.3: Diode characteristic
The PN junction diode may be looked at as the basic or entry level diode. Never- theless the basic PN junction diode is widely used in many applications from being a signal diode and detector, through being a clamp diode or transient suppressor across inductors or relay coils, through to high power rectification. In all these applications the basic PN junction diode is able to provide a very useful service.
As a result, these diodes are use dry the million each day.
2.1.1.2 Light Emitting Diode (LED)
LED, or Light emitting diode technology is widely used in today’s electronics equipment. Not only that, but LED technology has developed in recent years and apart from being as an indicator in electronics equipment, the technology is being used in displays as well as lighting.
Figure 2.4: LED Schematic
The rapid development has posed the question about what is LED technology likely to be used for next.
In fact well over 30 billion LEDs are manufactured each year and this number is rising. With new forms of light emitting diodes being developed that produce white light (white LEDs) and blue light (blue LEDs) they are likely to find even more uses, and the production of these diodes is likely to increase still further.
LEDs are used in a wide variety of applications. One of their first applications was as small indicator lamps. They were also used in alphanumeric displays, although in this particular application they have now been superseded by other forms of display. With recent developments light emitting diodes are being used instead of incandescent lamps for illumination. In these and many other applications. LEDs are in widespread use and are expected to remain so for many years to come.
The LED is a specialised form of PN junction that uses a compound junction. The semiconductor material used for the junction must be a compound semiconductor.
The commonly used semiconductor materials including silicon and germanium are simple elements and junction made from these materials do not emit light.
Instead compound semiconductors including gallium arsenide, gallium phosphide and indium phosphide are compound semiconductors and junctions made from these materials do emit light.
These compound semiconductors are classified by the valence bands their con- stituents occupy. For gallium arsenide, gallium has a valency of three and arsenic a valency of five and this is what is termed a group III-V semiconductor and there are a number of other semiconductors that fit this category. It is also possible to have semiconductors that are formed from group III-V materials.
The diode emits light when it is forward biased. When a voltage is applied across the junction to make it forward biased, current flows as in the case of any PN junction. Holes from the p-type region and electrons from the n-type region enter
the junction and recombine like a normal diode to enable the current to flow.
When this occurs energy is released, some of which is in the form of light photons.
It is found that the majority of the light is produced from the area of the junction nearer to the P-type region. As a result the design of the diodes is made such that this area is kept as close to the surface of the device as possible to ensure that the minimum amount of light is absorbed in the structure.
To produce light which can be seen the junction must be optimised and the correct materials must be chosen. Pure gallium arsenide releases energy in the infra read portion of the spectrum. To bring the light emission into the visible red end of the spectrum aluminium is added to the semiconductor to give aluminium gallium arsenide (AlGaAs). Phosphorus can also be added to give red light. For other colours other materials are used. For example galium phoshide gives green light and aluminium indium gallium phosphide is used for yellow and orange light. Most LEDs are based on gallium semiconductors.
2.1.2 Transistors
Prior to 1950, all electronic equipment used vacuum valves, which are bulbs with a faint Sheen, who dominated the industry. A normal vacuum valve heater con- sumed a couple of watts, so the team required bulky power that generated a considerable amount of heat, which was greatly concerned to designers. The re- sult was an outdated and heavy equipment. In 1951 Shockley invented the first transistor’s union, which was quite an event because it meant a big change. The impact of the transistor in electronics has been enormous, it has been the fore- runner of other inventions such as integrated circuits, optoelectronic devices and microprocessors. Currently, almost all electronic equipment used semiconductor devices. The changes have been most notable in the computer industry.
A transistor can be formed by two semiconductor diodes with a common area. In a transistor there are, therefore, three terminals. The common area is called base and two outdoor areas in contact with the base are the emitter and the collector.
So the transistor to operate correctly, the corresponding to the emitter-base diode union should polarize in direct sense, while the union corresponding to the collector- base must be polarized in the opposite direction.
Figure 2.5: Transistor Schematic
If we connect only the circuit Emitter-base, with direct polarization,the circuit sets an electric circulation from the emitter into the base through the union. Dis- connect power at the circuit, emitter-base and communicating the collector-base- polarized in the opposite direction, circulation practically both marriages will be emitter-base and collector-base, will establish a current between the emitter and the collector. This current is determined by the positive voltage of the transmitter and the refusal of the collector, always in relation to the base.
In transistor power amplification factor is the relationship between the emitter and the collector current.
The characteristic of the transistor by virtue of which, when the tension of the emitter, variations in collector current, can be entails that you can compare him with a thermionic valve. The emitter, the base and the collector of the transistor can be identified with the cathode, grid and anode triode, respectively.
2.1.2.1 Bipolar Transistor
Conventional or bipolar transistor is named because its operation involves flows of hollow, positively charged, and of electrons, or negatively charged. Other devices such as the FET are named monopolar because there is only a type flows.
Transistor terminals are emitter, collector and base. The base is the terminal that is connected to the intermediate zone of the transistor. The three parts of
the transistor are differentiated by the different levels of doping; minor doping is based, then is the collector and finally the transmitter.
Configurations
Depending on what the terminal common to input and output of the transistor, distinguishes three types of configurations:
Common base configuration. The base is the common input and output terminal, is linked to mass. The gain in this circuit is unity, but however the voltage gain can be very high and, therefore, also the gain in power. This configuration presents very little feedback between input and output, so it is used especially in high or very high frequency circuits.
Common emitter configuration. The transmitter is connected to Earth. The cur- rent gain is high (transistor Beta), the gain in voltage and power (the collector load dependent) is equally high. It is the most commonly used settings.
Common collector configuration. In this case, the terminal that is connected to ground is manifold. Entry applies to the base, as in previous configurations and load between the issuer and mass. This configuration has a gain in the beta of transistor current, the voltage gain is very similar, but less than the unit, and the gain in power is about the beta of the transistor. This setting is also called emitter follower; used to isolate or adapt impedances, since the base circuit offers the signal impedance beta times lower that is located on the transmitter. It is known as emitter follower because the emitter voltage ”follows” to the base voltage.
Figure 2.6: Transistor configuration
Characteristic curves
A transistor in the static regime is, only, under the action of the voltages that apply to polarize it. One way to summarize this operation is to use transistor
characteristic curves, which relate the voltages and currents. The voltages and currents that are used depend on the configuration of the transistor, but regardless of this, there are two types of curves: the characteristic of input and output property.
Input characteristics
The characteristic of input related to two magnitudes of input with output. In the case of the common emitter configuration collector-emitter is base depending on the voltage current emitter, for different values of voltage. The base current and voltage emitter are input variables, while the collector-emitter voltage is a magnitude of output.
If you have a configuration in common basis, its characteristic of input relate the current of the emitter with the emitter-base voltage, using the voltage collector- base as a parameter. The emitter current and the emitter-base with the magni- tudes of input voltage.
Figure 2.7: Transistor Input characteristics
The figure shows the different characteristics of input of two NPN transistors of Germanium and Silicon respectively depending on the voltage base-emitter for two values of collector-emitter voltage.
Output characteristics
The output characteristic has two of the three variables belonging to the output circuit. Curves that relate current collector, the base and the emitter voltage are
characteristics of output in emitter-common configuration, which relate the current of the emitter, collector and the collector-base voltage are curves corresponding to a common base configuration.
Figure 2.8: Transistor Output characteristics
Areas of operation
A bipolar transistor can operate in three different ways depending on the polar- ization that have two unions, emitter and retards. These areas can be seen in the family of a transistor output characteristic curves as shown in the figure.
Cutting area. For a silicon transistor, Vbe is less than 0.6 V (for germanium 0.2 V), both marriages are polarized in the opposite direction and strengths in the terminals can be considered negligible. In other words, the base voltage is not high enough to let it flow emitter current by the union base, so the collector current is equally negligible.
Active zone. The union emitter is polarized in direct sense (Vbe > 0.6 V) and union collector is in reverse, the reverse current flowing in the union of collector is beta times the current flowing in the direct sense base transmitter. This area is very important, since the transistor operates in it when used to amplify signals.
Zone of saturation. Both marriages, broadcaster and collector, are polarized in direct sense. The emitter current is very large, so the collector current is equally large. It is said that it has entered into saturation if the collector voltage is lower than the emitter voltage.
Limitations of transistors
A series of values that must be respected if the transistor is destroyed or lose their properties is not to appear in the datasheet of a transistor. Although these features are commented for bipolar transistors, the unipolar transistors are very similar.
Maximum collector current
This current is limited by the surface of the union and wires that connect the terminals of the transistor with the outer terminals. Some components specifies the values that can withstand a device continuously. These values, which are conditioned by thermal problems can exceed during a very short time if exceeding the average values without major setbacks.
Maximum dissipated power
The power that can dispel a transistor is conditioned by the maximum temperature that can withstand the semiconductor union collector-base, since like all diode the current reverse grows with temperature. So this junction temperature does not exceed the allowable values, often to 125◦C in silicon and 85◦C in germanium, it must provide devices that extract the heat generated in the unions abroad. Small discrete silicon transistors that are used in electronic circuitry, have a semicon- ductor surface of 1 or 2 mm2 and may dissipate 0.25 W of heat while the junction temperature exceeds the allowed values. By attaching a small radiator heat joined the housing of the transistor may be up to 1 W. Transistors half power (from 1 to 25 w) tend to be larger (4 the mm2) and have screws to fit heat radiators. High (125 W and more) power transistors have surfaces of semiconductor in the order of 25 mm2, welded to thick copper sheet with a robust radiator mounting screws.
The characteristics of power transistors is usually draw a curve called safe work, a combination of voltage and current collector emitter that in if it means the destruction of the device.
Maximum voltage
It is the maximum voltage of reverse polarization that can be applied to the tran- sistor. This value must be indicated so that the transistor enters the rupture zone, in which the device would be destroyed by excessive stress. Until the transistor enters the rupture zone, some transistors show a singular phenomenon known as
avalanche. Transistor supports large leak high pressure while not riding base cur- rent. But at the moment that begins to circulate a small current through the transistor base comes in total driving. If there is no limitation the collector cur- rent the transistor is destroyed. On the contrary, this phenomenon with current limiting can be used to obtain high values of current in generators of pulses for diode laser and other sophisticated applications.
Frequency of transition (Ft)
It is a feature of the behaviour of the transistor with frequency. The crossover frequency also called gain-bandwidth product, determines the point to which the gain in current of the transistor for that frequency (bf) is the unit. In other words the frequency up to which can be obtained by gain power transistor when used as an amplifier. This parameter specifies the capacity of the transistor to work at high frequencies.
Switching time
In logic circuits or digital, the transistor is usually in one of two States, cut (not leading) and saturation (fully leads). The passage from one State to another is not instantaneous because the transistor is not a perfect device, but it requires time. How children are the times to change state, more quickly is the transistor.
2.1.2.2 Unipolar Transistor
The operation of bipolar transistors outlined is based on the movement of two types of charges, electrons and holes, hence the prefix ’bi-’; In addition, PN unions are polarized in direct and reverse direction. Another very important type of transistors is the unipolar one based on the movement of a single type of charges, electrons or holes, so the prefix ’uni-’. In this type of transistor, PN joints are always in reverse polarized. The functioning of these transistors is significantly different from the bipolar.
Unipolar transistors are divided into two groups, the transistors of union of effect field, JFET or FET, which in turn are divided into N-channel transistors and P channel transistors, and metal-oxide - semiconductor MOSFET or field effect tran- sistors. Within this group are two subgroups and enrichment MOSFET MOSFET of impoverishment, which are divided as the FET in N-channel and P-channel.
2.1.3 Thyristors
Thyristors can take many forms, but they have certain things in common. All of them are solid state switches which act as open circuits capable of withstanding the rated voltage until triggered. When they are triggered, thyristors become low-impedance current paths and remain in that condition until the current either stops or drops below a minimum value called the holding level. Once a thyristor has been triggered, the trigger current can be removed without turning off the device.
Silicon controlled rectifiers (SCRs) and triacs are both members of the thyristor family. SCRs are unidirectional devices where triacs are bidirectional. An SCR is designed to switch load current in one direction, while a triac is designed to conduct load current in either direction.
Structurally, all thyristors consist of several alternating layers of opposite P and N silicon, with the exact structure varying with the particular kind of device. The load is applied across the multiple junctions and the trigger current is injected at one of them. The trigger current allows the load current to flow through the device, setting up a regenerative action which keeps the current flowing even after the trigger is removed.
These characteristics make thyristors extremely useful in control applications.
Compared to a mechanical switch, a thyristor has a very long service life and very fast turn on and turn off times. Because of their fast reaction times, regen- erative action and low resistance once triggered, thyristors are useful as power controllers and transient overvoltage protectors, as well as simply turning devices on and off. Thyristors are used in motor controls, incandescent lights, home ap- pliances, cameras, office equipment, programmable logic controls, ground fault interrupters, dimmer switches, power tools, telecommunication equipment, power supplies, timers, capacitor discharge ignitors, engine ignition systems, and many other kinds of equipment.
Although thyristors of all sorts are generally rugged, there are several points to keep in mind when designing circuits using them. One of the most important is to respect the devices rated limits on rate of change of voltage and current (dv/dt and di/dt). If these are exceeded, the thyristor may be damaged or destroyed.
On the other hand, it is important to provide a trigger pulse large enough and
fast enough to turn the gate on quickly and completely. Usually the gate trigger current should be at least 50 percent greater than the maximum rated gate trigger current. Thyristors may be driven in many different ways, including directly from transistors or logic families, power control integrated circuits, by optoisolated triac drivers, programmable unijunction transistors (PUTs) and SIDACs.
The bistable action of thyristors is readily explained by analysis of the structure of an SCR. This analysis is essentially the same for any operating quadrant of triac because a triac may be considered as two parallel SCRs oriented in opposite di- rections. Figure 1.9(a) shows the schematic symbol for an SCR, and Figure 1.9(b) shows the P-N-P-N structure the symbol represents. In the two-transistor model for the SCR shown in Figure 1.9(c), the interconnections of the two transistors are such that regenerative action occurs. Observe that if current is injected into any leg of the model, the gain of the transistors (if sufficiently high) causes this current to be amplified in another leg. In order for regeneration to occur, it is necessary for the sum of the common base current gains (α) of the two transistors to exceed unity.
Figure 2.9: Thyristor Schematic
Therefore, because the junction leakage currents are relatively small and current gain is designed to be low at the leakage current level, the PNPN device remains
off unless external current is applied. When sufficient trigger current is applied (to the gate, for example, in the case of an SCR) to raise the loop gain to unity, regeneration occurs and the on-state principal current is limited primarily by ex- ternal circuit impedance. If the initiating trigger current is removed, the thyristor remains in the on state, providing the current level is high enough to meet the unity gain criteria. This critical current is called latching current.
In order to turn off a thyristor, some change in current must occur to reduce the loop gain below unity. From the model, it appears that shorting the gate to cathode would accomplish this. However in an actual SCR structure, the gate area is only a fraction of the cathode area and very little current is diverted by the short. In practice, the principal current must be reduced below a certain level, called holding current, before gain falls below unity and turn-off may commence.
In fabricating practical SCRs and Triacs, a shorted emitter design is generally used in which, schematically, a resistor is added from gate to cathode or gate to MT1. Because current is diverted from the N-base through the resistor, the gate trigger current, latching current and holding current all increase. One of the principal reasons for the shunt resistance is to improve dynamic performance at high temperatures. Without the shunt, leakage current on most high current thyristors could initiate turn-on at high temperatures.
Sensitive gate thyristors employ a high resistance shunt or none at all; conse- quently, their characteristics can be altered dramatically by use of an external resistance. An external resistance has a minor effect on most shorted emitter designs.
Junction temperature is the primary variable affecting thyristor characteristics.
Increased temperatures make the thyristor easier to turn on and keep on. Conse- quently, circuit conditions which determine turn-on must be designed to operate at the lowest anticipated junction temperatures, while circuit conditions which are to turn off the thyristor or prevent false triggering must be designed to operate at the maximum junction temperature. Thyristor specifications are usually written with case temperatures specified and with electrical conditions such that the power dissipation is low enough that the junction temperature essentially equals the case temperature. It is incumbent upon the user to properly account for changes in characteristics caused by the circuit operating conditions different from the test conditions.
Turn-on of a thyristor requires injection of current to raise the loop gain to unity.
The current can take the form of current applied to the gate, an anode current resultingfrom leakage, or avalanche breakdown of a blocking junction. As a result, the breakover voltage of a thyristor can be varied or controlled by injection of a current at the gate terminal. Figure 1.10 shows the interaction of gate current and voltage for an SCR.
When the gate current Ig is zero, the applied voltage must reach the breakover voltage of the SCR before switching occurs. As the value of gate current is in- creased, however, the ability of a thyristor to support applied voltage is reduced and there is a certain value of gate current at which the behavior of the thyristor closely resembles that of a rectifier. Because thyristor turn-on, as a result of ex- ceeding the breakover voltage, can produce high instantaneous power dissipation non-uniformly distributed over the die area during the switching transition, ex- treme temperatures resulting in die failure may occur unless the magnitude and rate of rise of principal current (di/dt) is restricted to tolerable levels. For normal operation, therefore, SCRs and triacs are operated at applied voltages lower than the breakover voltage, and are made to switch to the on state by gate signals high enough to assure complete turn-on independent of the applied voltage. On the other hand, diacs and other thyristor trigger devices are designed to be triggered by anode breakover. Nevertheless they also have di/dt and peak current limits which must be adhered to.
Figure 2.10: Thyristor graph
In the next figure you can watch the different types of thyristors and their own symbols:
Figure 2.11: Thyristor’s types
2.2 Devices
For this project we have used a number of devices that will be described below . The two devices are less than a year and have been transferred by the company Rohde & Schwarz for using.
2.2.1 Power Supply HMC8043
The three channels HMC8043 power supply with his specifications and wide range of functions is ideal for use in development labs and industrial environments.
Thanks to his high energy efficiency, the linear power supply remain cool and quiet, even at maximum load.
Practical interfaces and connectors allow users to work quickly and conveniently with the HMC8043, even in 19” racks.
The HMC804x family consists of three models with a maximum total power of up to 100 W and a continuous voltage range from 0 V to 32 V. The one-channel HMC8041 delivers a maximum of 10 A, the two-channel HMC8042 a maximum of
5 A and the three-channel HMC8043 a maximum of 3 A per channel. The three- channel model enable users to connect multiple outputs in parallel or in series to increase the voltage or current. The outputs are galvanically isolated, floating, and protected against overloading and short circuits. Voltage, current and power values are output on a brilliant QVGA display
The HMC8043 offers a wide range of logging functions, an integrated energy meter and electronic fuses that can be individually combined for each channel, making it ideal for hardware developers, labs and industrial environments. Linear switch- ing power supplies ensure high efficiency, for minimum heat dissipation even at full load. Developers and industrial users benefit from useful functions such as sequenced start of channels, EasyArb and EasyRamp functions that are directly programmable on the device, an analog input for external control of voltage values, an external trigger input for controlling channels and arb steps, and adjustable overvoltage/overpower protection for each channel.
All connectors, including SENSE, are available on the rear panel. A cage clamp facilitates rack installation and de-installation. The LXI-compliant power supply can be controlled via LAN, USB or an optional GPIB interface. The CDC (virtual COM port) and TMC classes are supported for communications via USB. The remote control commands are based on the SCPI standard.
2.2.1.1 Working Manual
Front Panel:
1 Display - Color display (320 x 240 pixel) 6 HELP Integrated help display 2 Interactive soft menu keys All relevant functions are directly accessible 7 SHIFT Shift key to activate the 3 Function keys To be used as numeric keypad in SHIFT function numeric keypad
CH1 - Settings for channel 1 8 Universal knob with arrow keys Setting
CH2 - Settings for channel 2 desired values (edit keys)
CH3 - Settings for channel 3 9 POWER On/Off for standby mode
CH1 ON/OFF - Activating / Deactivating channel 1 10 USB connector USB connector CH2 ON/OFF - Activating / Deactivating channel 2 to save parameters
CH3 ON/OFF - Activating / Deactivating channel 3 11 CH1 (4 mm safety sockets) -
ARB - EasyArb function Outputs channel 1; 0 V to 32 V / 3 A (33 W max.)
ADV - Advanced functions (e.g. OVP, OPP, Fuse etc.) 12 CH2 (4 mm safety sockets) -
MEAS - Logging function / power display Outputs channel 2; 0 V to 32 V / 3 A (33 W max.) MASTER ON/OFF - Selected channels may be switched ON or OFF 13 CH3 (4mm safety sockets) -
TRACK - Activating the tracking function Outputs channel 3; 0 V to 32 V / 3 A (33 W max.) TRIG - Manual trigger
4 SAVE/RECALL Loading/storing of instrument settings 5 SETUP Access to basic instrument settings
Figure 2.12: HMC8043 front panel
Back Panel:
Figure 2.13: HMC8043 back panel
14 Terminal block - 17 USB interface
connections for all channels 18 Ground terminal
(voltage/ current interface, trigger, sense) 19 Low-heat device socket with power switch for easy integration into 19 rack systems 20 Fuse
15 IEEE-488 (GPIB) interface (option) 21 Power switch Factory-installed only 22 Kensington lock 16 Ethernet (LAN) interface
Interface:
Figure 2.14: HMC8043 interface
1 Master output (ON/OFF) 13 Constant current (CC)
2 Sequencing 14 Display of voltage
3 Logging 15 Fuse tripped
4 Statistics 16 Sense detection
5 Total power consumption 17 Overload protection (OPP) 6 Analog In Trigger In 18 Electronic fuse set 7 Type of interface: 19 Fuse linking GPIB / USB TMC / USB VCP / LAN 20 Display of current
8 Name of channel 21 EasyRamp
9 Analog In (channel) 22 Energy meter 10 Constant voltage (CV) 23 Channel power 11 Overvoltage protection (OVP)
12 EasyArb
Limits:
The HMC8043 is equipped with a protective overload feature. The protective over- load feature prevents damage to the instrument and is intended to protect against a possible electrical shock. The maximum values for the instrument must not be exceeded. The protection limits are listed on the front panel of the HMC8043 to ensure the safe operation of the instrument.
These protection limits must be adhered to:
Max. output voltage 32 VDC
Max. output current 3 A / 5 A / 10 A (max.100 W)
Max. voltage against earth 250 VDC
2.2.1.2 Programming Manual
Ethernet (LAN) Interface
The settings of the parameter will be done after selecting the menu item ETHER- NET and the soft key PARAMETER. You can set a fix IP address or a dynamic IP setting via the DHCP function.
To set up the connection the IP address of the instrument is required. It is part of the resource string used by the program to identify and control the instrument.
The resource string has the form:
The default port number for SCPI socket communication is 5025. IP address and port number are listed In the Ethernet Settings of the HMC8043
If the LAN is supported by a DNS server, the host name can be used instead of the IP address.
The DNS server (Domain Name System server) translates the host name to the IP address. The resource string has the form:
To assign a host name to the HMC8043, select SETUP button ¿ Misc ¿ Device name.
SCPI Command Structure
SCPI commands consist of a so-called header and, in most cases, one or more parameters. The header and the parameters are separated by a white space (ASCII code 0 to 9, 11 to 32 decimal,e.g. blank). The headers may consist of several mnemonics (keywords). Queries are formed by appending a question mark directly to the header.
The commands can be either device-specific or device-independent (common com- mands).
Common and device-specific commands differ in their syntax.
Common (= device-independent) commands consist of a header preceded by an asterisk (*) and possibly one or more parameters.
The mnemonics feature a long form and a short form. The short form is marked by upper case letters, the long form corresponds to the complete word. Either the short form or the long form can be entered; other abbreviations are not permitted.
Example: MEASure:CURRent? is equivalent to MEAS:CURR?
2.2.2 Digital Multimeter HMC8012
The digital multimeter HMC8012 is starting off the new series.
In contrast to the class standard of 5- 12digit displays, the HAMEG instrument of- fers a 5- 34 digit display (480,000 points) resulting in measurement ranges that are four times higher without any requirement of range switching. It facilitates mea- surements in the measurement categoryII with a voltage of up to 600V, as opposed to the standard of only 300V in this instrument class. With the HMC8012, current measurements across the entire range can be performed with only one connector.
This eliminates any manual switching during range transfers. Additionally, an integrated watt meter enables power measurement in the DC range.
With a base accuracy of 0.015% in the DC range, the multimeter shows up to 3 measured values on the brilliant TFT color display. The display may include a DC voltage, a AC voltage and related statistics, for instance. Altogether, the multimeter offers 12 different measurement functions: VDC and IDC, True RMS VAC and IAC, frequency, 2- and 4-wire resistance, capacity, continuity, diode, temperature and performance. Extensive mathematics functions such as limit testing, min/max, means, offset, DC performance, dB and dBm are available to support the user during his measurement tasks and round off the multimeter features.
The performance of a true RMS measurement in the AC+DC range is a very useful option. The option to display three measurement values simultaneously allows users to conveniently measure DC voltages with overlapping AC voltage or direct currents with overlapping alternating currents. This function is useful for the development of LED lighting, for instance, which is typically controlled by means of PWM-regulated signals.
Multimeters with standard monochromatic screens are able to implement limit functions only by means of a signal tone. By contrast, the HMC8012 with its
color TFT display also allows a visual implementation of the function. A primary measurement value that is within the defined limit range is shown in green whereas a higher or lower value is displayed in red. The HMC8012 also offers an acoustic option. The HMC8012 can also solidly hold its ground against competitors in regards to measurement rates: For instance, up to 200 measurements per second are possible (depending on the selected range). The distinguishing feature is the fact that the data logging function allows the user to record these measurements not only on the internal memory which includes 50,000 measurement points. The only record limit for a connected USB stick in FAT or FAT32 format is the capacity of the used storage medium. This makes the HMC8012 the ideal instrument to perform a series of measurements without PC or remote infrastructure that is virtually unlimited in length.
2.2.2.1 Working Manual
Front Panel:
Figure 2.15: HMC8012 front panel
1 Display Color display (320 x 240 pixel) 6 HELP Integrated help display 2 Interactive soft menu keys All relevant functions are accessible 7 SHIFT Shift key to activate the 3 Function keys To be used as numeric keypad in SHIFT function numeric keypad
DC V DC voltage measurement 8 Universal knob with arrow keys Setting
DC I DC current measurement desired values (edit keys)
AC V AC voltage measurement 9 V/R/C/Diode connector Input for
AC I AC current measurement voltage, frequency, resistance
Ω Resistance measurement, 2- and 4-wire and temperature measurement
Diode / transmission measurement 10 COM connector
SENSOR Temperature measurement Common measurement input for voltage, resistance, HOLD Measurement with hold function temperature and capacity measurement
NULL Zero point of the measurement section 11 A connector Input for current measurement
CAP Capacity measurement 12 LO/HI connectors
TMEAS Limit measurement / mathematical functions / statistic Sensor for resistance and temperature measurement
TRIG Manual trigger 13 FUSE Measuring circuit fuse
4 SAVE/RECALL Loading/storing of instrument settings 14 USB connector to save parameters 5 SETUP Access to basic instrument settings 15 POWER On/Off for standby mode
Back Panel:
Figure 2.16: HMC8012 back panel
16 IEEE-488 (GPIB) interface (option) 21 Fuse
Factory-installed only 22 Power switch
17 Kensington lock 23 Voltage selector (115 V or 230 V)h 18 LAN connector
19 USB connector
20 Low-heat device socket with power switch
2.2.2.2 Programming Manual
For the section of programming we will use the same guidelines as for the previous device.
2.2.3 Others
Finally should be noted the form of interconnection between devices, so we will use rj45 cables:
Figure 2.17: Ethernet rj45 cable
And a switch that will serve both access devices and access to the network:
Figure 2.18: Switch device
2.3 Software
Now, It’s the time to explain all the procedures to follow to have all the necessary to measure any circuit only using the computer software.
2.3.1 Python
This project has been realized with the Python programming language as it is a simple language and focused on objects so it will allow us to work with the equipment as if it were physical objects .(In this project we have used Windows 8.1 as O.S. but Python is a cross-platform language so it can be used either in Linux or OSX)
Python is a language that has several text editors and countless libraries so we choose something according to what will friendly.On this case , the program has been used Python (x,y) which can be downloaded from the page of Google :
Figure 2.19: Python(x,y) download
This program collects various text editors and many libraries including PyVISA is that it will be important to connect with the measuring devices . Likewise , it integrates a very similar interface to Matlab interface called Spyder at the dive into Python and specifically in this interface occurs more conveniently than with other text editors.
Figure 2.20: Python(x,y) interface
Figure 2.21: Spyder interface
As we see this interface is very intuitive and presents great resemblance to the Matlab interface.
2.3.2 National Instruments VISA
Another important programs installed will be the National Instruments VISA will allow us to observe , monitor and analyze any measuring device that we connected to the computer and check the connections between them. To do this , we go to the website NI-VISA and proceed to download the program.
Figure 2.22: NI-VISA download
Once installed the program, We can watch all the features it has . Also check if the devices work properly.
Figure 2.23: NI-VISA Interface
Figure 2.24: NI-VISA Trace
Warning: The VISA only allow the access to one program at the same time so if you want to run a new program or use the instrument with other software, please close the first one before.
Setups and Test Reports
3.1 Devices’ connection
The most important thing when it comes to making good the measures is to make a good connection between all the devices that are to be used . For this, both the computer and devices to a switch which in turn will be connected to the mains lab , so all devices will be connected to the same network and any device or computer that is connected is connected to said network may make use of measurement devices .Even if the network is connected to the internet we could connect only devices from anywhere by accessing the IP address.
3.2 Leds and Diodes
3.2.1 Setup
A series of montages that are detailed below should be performed to obtain the values of the circuits and LEDs studied in theory.
3.2.1.1 Circuits
In an electronics circuit an LED, light emitting diode behaves very much like any other diode. As they are often used to indicate the presence of a voltage at a
34
particular point, often being used as a supply rail indicator. When used in this fashion there must be a current limiting resistor placed in the circuit. This should be calculated to give the required level of current. For many devices a current of around 20 mA is suitable, although it is often possible to run them at a lower current. If less current is drawn the device will obviously be dimmer. When calculating the amount of current drawn the voltage across the LED itself may need to be taken into consideration. The voltage across a LED in its forward biased condition is just over a volt, although the exact voltage is dependent upon the diode, and in particular its colour. Typically a red one has a forward voltage of just under 2 volts, and around 2.5 volts for green or yellow.
Great care must be taken not to allow a reverse bias to be applied to the diode.
Usually they only have a reverse breakdown of a very few volts. If breakdown occurs then the LED is destroyed. To prevent this happening, an ordinary silicon diode can be placed across the LED in the reverse direction to prevent any reverse bias being applied.
To test the program as well as the main characteristics of the LEDs We perform the following basic circuit:
Figure 3.1: Theoretical LED circuit
Below, the actual image of the circuit (ideally mount all a breadboard ) :
Figure 3.2: LED circuit
We change only the diode for each independent case.
Figure 3.3: Ge diode
Figure 3.4: Red LED
Figure 3.5: Clear LED
Finally , in a didactic way , the following circuits and their testing as development are suggested for laboratory practices:
Power Diode Rectifier
Figure 3.6: Power Diode Rectifier
Power diodes can be used individually as above or connected together to produce a variety of rectifier circuits such as Half-Wave, Full-Wave or as Bridge Rectifiers.
Each type of rectifier circuit can be classed as either uncontrolled, half-controlled or fully controlled were an uncontrolled rectifier uses only power diodes, a fully controlled rectifier uses thyristors (SCRs) and a half controlled rectifier is a mixture of both diodes and thyristors.
Half Wave Rectifier Circuit
Figure 3.7: Half Wave Rectifier
A rectifier is a circuit which converts the Alternating Current (AC) input power into a Direct Current (DC) output power. The input power supply may be either a single-phase or a multi-phase supply with the simplest of all the rectifier circuits being that of the Half Wave Rectifier.
The power diode in a half wave rectifier circuit passes just one half of each complete sine wave of the AC supply in order to convert it into a DC supply. Then this type of circuit is called a half-wave rectifier because it passes only half of the incoming AC power supply as shown below.
Half-wave Rectifier with Smoothing Capacitor
Figure 3.8: Half-wave Rectifier with Smoothing Capacitor
When rectification is used to provide a direct voltage ( DC ) power supply from an alternating ( AC ) source, the amount of ripple voltage can be further reduced by using larger value capacitors but there are limits both on cost and size to the types of smoothing capacitors used.
For a given capacitor value, a greater load current (smaller load resistance) will discharge the capacitor more quickly and so increases the ripple obtained. Then for single phase, half-wave rectifier circuit using a power diode it is not very practical to try and reduce the ripple voltage by capacitor smoothing alone. In this instance it would be more practical to use Full-wave Rectification instead.
The Full Wave Bridge Rectifier
Figure 3.9: Diode Bridge Rectifier
This type of single phase rectifier uses four individual rectifying diodes connected in a closed loop bridge configuration to produce the desired output. The main advantage of this bridge circuit is that it does not require a special centre tapped transformer, thereby reducing its size and cost. The single secondary winding is connected to one side of the diode bridge network and the load to the other side as shown before.
Full-wave Rectifier with Smoothing Capacitor
Figure 3.10: Full-wave Rectifier with Smoothing Capacitor
The smoothing capacitor converts the full-wave rippled output of the rectifier into a smooth DC output voltage. Generally for DC power supply circuits the smoothing capacitor is an Aluminium Electrolytic type that has a capacitance value of 100uF or more with repeated DC voltage pulses from the rectifier charging up the capacitor to peak voltage.
3.2.1.2 Program
Development of automation of measures we should develop a program in Python that takes place the function increase the source, check the circuit data, store the corresponding measures and draw the graph of V/I. Therefore be deduced the following flowchart for the development of the program.
Figure 3.11: Diode flowchart
In the appendix A is the code for possible use and/or expansion. The student simply must run the program after having mounted the circuit to obtain the data in a table and .csv format and graphic in .jpg as you can watch on the results.
3.2.2 Results
To observe that software development was correct, we estimate the characteristics of the mentioned diodes and obtained the following results showing that everything was right.
Previously, We could check that we obtained the graphs and the files watching the program folder:
Figure 3.12: Files folder
The Germanium diode has a much lower threshold voltage than the LED diodes and it is correctly shown in the graph below.
Iin 0.00e+00 0.00e+00 2.00e-04 5.99e-04 1.19e-03 1.69e-03 2.29e-03 2.89e-03 3.39e-03 4.00e-03 4.59e-03 5.19e-03 5.70e-03 6.30e-03 6.89e-03 7.49e-03 8.09e-03 8.60e-03 9.19e-03 9.79e-03
Vout 8.80e-04 3.00e-01 5.12e-01 5.75e-01 6.04e-01 6.22e-01 6.36e-01 6.46e-01 6.54e-01 6.61e-01 6.68e-01 6.73e-01 6.78e-01 6.82e-01 6.86e-01 6.90e-01 6.93e-01 6.97e-01 7.00e-01 7.02e-01
Table 3.1: Characteristics of Ge diode
Figure 3.13: Characteristics of Ge diode
The red LED was done by GaAsP his wavelength is around 630 - 660 nm and the threshold voltage is 1.8 V theoretically and below we can observe if the results are correct.
Iin 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00 1.00e-04 2.99e-04 5.99e-04 8.99e-04 1.19e-03 1.50e-03 1.79e-03 2.00e-03 2.29e-03 2.59e-03 2.89e-03 3.20e-03 3.50e-03 3.79e-03
Vout 1.82e-03 3.01e-01 6.01e-01 9.02e-01 1.20e+00 1.50e+00 1.73e+00 1.78e+00 1.81e+00 1.82e+00 1.84e+00 1.85e+00 1.86e+00 1.86e+00 1.87e+00 1.88e+00 1.89e+00 1.89e+00 1.90e+00 1.91e+00
Table 3.2: Characteristics of red LED
Figure 3.14: Characteristics of red LED
The clear LED threshold voltage was around 1.9 V theoretically so we can affirm that the results are correct.
Iin 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00 2.00e-04 5.99e-04 1.10e-03 1.60e-03 2.09e-03 2.70e-03 3.20e-03 3.79e-03 4.40e-03 4.89e-03 5.49e-03 6.10e-03 6.59e-03 7.19e-03
Vout 1.61e-03 3.02e-01 6.02e-01 9.01e-01 1.20e+00 1.50e+00 1.71e+00 1.80e+00 1.86e+00 1.90e+00 1.92e+00 1.95e+00 1.96e+00 1.98e+00 1.99e+00 2.01e+00 2.02e+00 2.03e+00 2.04e+00 2.05e+00
Table 3.3: Characteristics of clear LED
Figure 3.15: Characteristics of clear LED
3.3 Transistors
3.3.1 Setup
For the development of the analysis of transistors we made in this case a test of the program on the OC1045 bipolar transistor with the following characteristics:
Figure 3.16: OC1045 datasheet
3.3.1.1 Circuits
Before mounting the circuit, it is necessary to calculate the correct resistance value looking the transistor’s datasheet.As well as, to be careful about the maximum limits of voltage according of the same datasheet. It is also very important to check if the transistor is a NPN or a PNP and to apply the correct configuration, in this case we have a PNP transistor.
To test the program as well as the main characteristics of the transistors we perform the following basic circuit in common-emitter configuration.
Figure 3.17: Theoretical transistor circuit
Below, the actual image of the circuit (ideally mount all a breadboard ) :
Figure 3.18: Transistor circuit I
Figure 3.19: Transistor circuit II
Finally , another kind of transistor like JFET or MOSFET can be analysing by the student following the same way.
3.3.1.2 Program
For the development of the transistor characteristics automation we should differ- entiate two parts. First part, the input characteristics, can be calculated by the same program that the diode characteristics because it is only analyse the voltage out in function of the input current. Second part, the collector characteristic or output characteristics have to be modelled following the below flowchart:
Figure 3.20: Transistor flowchart
In the appendix A is the code for possible use and/or expansion. The student simply must run the program after having mounted the circuit to obtain the data in a table and .csv format and graphic in .jpg as you can watch on the results.
3.3.2 Results
It can be observed that the results agree with the theory so we can assume that the automation is correctly achieved.
Iin 0.00e+00 0.00e+00 1.00e-04 5.00e-04 1.00e-03 1.60e-03 2.20e-03 2.79e-03 3.29e-03 3.89e-03 4.49e-03 5.10e-03 5.59e-03 6.19e-03 6.79e-03 7.40e-03 8.00e-03 8.50e-03 9.10e-03 9.70e-03
Vout -1.14e+00 -1.08e+00 5.69e-01 6.43e-01 6.69e-01 6.85e-01 6.96e-01 7.04e-01 7.11e-01 7.17e-01 7.22e-01 7.26e-01 7.30e-01 7.33e-01 7.36e-01 7.39e-01 7.42e-01 7.44e-01 7.47e-01 7.49e-01
Table 3.4: Input characteristics of bipolar transistor
Figure 3.21: Input characteristics of bipolar transistor
Figure 3.22: Output characteristics of bipolar transistor