Electronic Circuit & Systems Design H7076 2017 Electronic Circuit & Systems Design Laboratory Handbook Part 2: Experiment A Bipolar Transistor Content:    Transistor Characteristic Transistor as switch Amplifier Remember that you should simulate all the circuits to determine the values for passive components in the lab sessions (or any other time in Richmond), and do all the measurements in the practical sessions. The ELVIS boards will be used in the laboratory sessions, here you should build all the circuits using discrete devices and select components base on the previously done simulations. Characterization of these circuits can be done use the virtual ELVIS board instruments or the table top equipment. Aims 1. 2. 3. To become familiar with the characteristics of a single transistor, to extract its performance parameters, and to compare the measured values with the values given in the data sheet. To gain an understanding of transistor operation in simple single stage switching and amplifier circuits. To acquire a basic knowledge of circuit simulation and virtual instrumentation techniques (using Multisim) by comparing these with experiment This experiment is based on a BC107/8/9 bipolar transistor You must simulate your circuits using Multisim before attending the practical session (there is enough time in the lab sessions, but you can work on the simulation at any time using the PCs in Richmond). You will lose marks if a full range of simulations are not included in your final report. You should note that while circuit simulation is a useful and powerful tool it is only a part of the design procedure. You will still be required to calculate and justify the component values you have chosen. However, the ability to rapidly evaluate your design by simulation and if necessary modify it to achieve the required results is increasingly the procedure used professionally. Note that the transistor chosen for this experiment is one of the devices in the Multisim library, and this should be selected for your simulations. 1/5 Electronic Circuit & Systems Design H7076 2017 I. DC Transistor characteristic Tasks: 1. Download the datasheet and familiarize yourself with the transistor. 2. Simulate the output characteristic of the transistor, use appropriate bias currents and voltages, and at least 3 different base currents. 3. Connect the BC109 (or BC107 or BC108) to the ELVIS board and measure the transistor output characteristic, use the same currents and voltages as in your simulation 4. Compare the measured and simulated characteristic with the manufacturer’s data sheet. 5. Draw or print the transistor characteristics, annotated the graph and graphically extract the output resistance of the device. 6. Estimate the β ratio of the transistor using the measured characteristic and compare all values to the datasheet. II. Transistor as switch The purpose of this experiment is to switch the transistor between the extremes of saturation and cut-off. Based on the characteristic curves for the BC109 (or BC107 or BC108), choose suitable component values for the circuit shown in Fig. 1 (calculations), simulate the circuit using Multisim, and construct it on the NIELVIS board. Figure 1: Transistor as switch. When Vin =5 V the transistor should be fully ON and when Vin = 0 V the transistor will be fully OFF. Consider the maximum ratings for the LED and the transistor in your design. Tasks: 1. When the transistor is ‘ON’, use the digital voltmeter (DVM) to simulate and measure: a. the voltage across the transistor b. the voltage across the collector resistor (and hence calculate the current) c. the voltage across the base resistor (calculate the current) 2. Repeat 1) when the transistor is ‘OFF’. 3. From these values calculate the dissipated power in both the ‘ON’ and ‘OFF’ states. 4. Compare the power dissipated in the LED, collector resistor and transistor when in the ‘ON’ state and when in the ‘OFF’ state. 2/5 Electronic Circuit & Systems Design H7076 2017 III. Common emitter amplifier A common emitter amplifier (Fig. 2) should be designed to operate at midpoint bias. Use the characteristics in the data sheet to determine the bias point and design an appropriate voltage divider bias network. Simulate the circuit, and build it on the NI Elvis board. Choose appropriate component values to provide a voltage gain of 80. Use midpoint biasing to design the circuit, and follow the rules specified in the lecture. The collector bias current should be ≈1% of the absolute maximum collector current given in the datasheet. Figure 2: Common emitter amplifier Choose appropriate input and output coupling capacitors to allow the circuit to function properly down to ≈20 Hz. (It may be best to use small electrolytic capacitors, consider this option). Tasks: 1. Show calculations for all components. 2. Estimate the input and output impedances of the amplifier you have designed. 3. Simulate and measure the collector-emitter voltage (VCE) • Does this agree with your design? If not, explain why. 4. Simulate and measure the collector current for the quiescent state before you apply a signal. • Does this agree with your design? If not, explain why. 5. Simulate and measure the gain of the amplifier for different frequencies, by comparing Vout with Vin using two channels of the oscilloscope. Select a suitable frequency range, and make sure the cutoff frequency of the amplifier can be extracted. Record the measurement in your logbook (about 15 spot frequency measurements should be sufficient, with logarithmic spacing). • Plot the results. Create a Bode plot (Gain in dB vs frequency) with appropriate axis and scaling. 6. Add a suitable value bypass capacitor in parallel with the emitter resistor and repeat the gain simulations and measurements. • Explain how you arrived at your choice of capacitor value (calculations!) • Plot the results on the same graph • Explain the differences in amplifier performance. 3/5 Electronic Circuit & Systems Design H7076 2017 Report Your mark will only be determined based on your report. Make sure you submit a complete and concise report. Also consider the comment concerning the assessment given in the Laboratory Handbook Part 1. The following points are very important:  You have to include all your results (from calculations, simulations, and measurements).  You have to discuss your results  Use the Word or LATEX template available on Study Direct  The complete report including cover page, references, but excluding the self-assessment should not be longer than 10 pages  Perform a realistic self-assessment as described at the end of this document. To do so you have to refer to the marking scheme attached to this document (and available on Study Direct). Based on the masking scheme judge your report against every criterion specified in the marking table (e.g. by highlighting the corresponding field). Afterwards calculate the mark you think you deserve for your report (this will not necessarily be your final mark!) Self-assessment A realistic self-assessment has to be done, and included into your report. The self-assessment is worth 10% of the final mark! The self-assessment does not contribute to the page count towards the page limit of 10 pages. The assessment criteria for this report are given on page 5. A corresponding word and pdf file is also available on Study Direct. Consider the following:  Judge your report against every criterion.  Clearly indicate how you judge your report.  Make sure the marks you give yourself are reasonable.  Calculate the resulting mark you think you deserve.  You can use the provided marking scheme also to optimize your report and hence your mark. 4/5 Electronic Circuit & Systems Design H7076 Weight Simulation 2017 Criteria Mark 0% 18% 35% 40% 60% You did set up the simulation, and there are some measurements, but it is not clear what the base current is. A better mark would require the following: Simulation results and a nice graph of the output characteristic for multiple base currents, a calculation of the base currents, and some effort concerning the extraction of the performance parameters (gain, output resistance, and the transition between the linear and the active region) You did set up the simulation, and there are some results, but they are not complete. A better mark would require the following: Simulation results and a nice graph of the output characteristic for multiple base currents, a calculation of the base currents, and some effort concerning the extraction of the performance parameters (gain, output resistance, and the transition between the linear and the active region) You simulated a meaningful output characteristic, and presented the results in an understandable way. Unfortunately the extraction of the performance parameters (gain, output resistance, and the transition between the linear and the active region) is incomplete. 11% Simulation I: Simulation of the transistor DC characteristic No simulation at all. You tried to set up the simulation, but there are no results. 10% Simulation II: Simulation of the transistor as switch to turn on a LED No simulation at all. You tried to set up the simulation, but there are no results. You designed a usable circuit and demonstrated switching operation, unfortunately it is not clear how you selected the resistor values. No simulation at all. You tried to set up the simulation and to calculate the values of the required resistors, but there are no usable results. You tried to set up a circuit which looks OK, but there is measurement showing any gain You calculated values for all resistors, your simulation somehow works and you demonstrated that there is gain. A better mark would require the following: Simulation results and a nice graph of the frequency response for at least 15 different well selected frequencies, a calculation of the coupling capacitors, calculation of the bypass capacitor (incl. associated simulation results) and some effort concerning the performance parameter extraction (gain, cutoff frequency) from the Bode plot. 0% 18% 35% 40% You tried to connect the transistor to the board, but there are no usable results. You did set up a circuit on the ELVIS board. This circuit looks basically fine, but your measurements do not show the typical base current and the collector-emitter voltage dependency of the emitter current. At the same time you should invest more effort in presenting your results, extracting the important performance parameters (gain, output resistance, quantification of the active region), and discussing the results. Also comparing the measured results to the data sheet and your simulation is an important point. 14% Simulation III: Simulation of a common emitter amplifier Measurement 14% 13% 18% Measurement I: Measurement of the transistor DC characteristic using the ELVIS board Measurement II: Using the transistor as switch to control a LED on the ELVIS board Measurement III: Building a common emitter amplifier on the ELVIS board. Report No effort at all. No effort at all. You tried to control the LED using the transistor using the ELVIS board, but there are no usable results. Very good simulation, this part includes all the required simulation results, a nice graph, the extraction of all or nearly all performance parameters (gain, output resistance, and the transition between the linear and the active region). Additionally, you compared your results to the data sheet and discussed them. This is a very good design and simulation which includes all required currents and voltages, and a calculation of the efficiency of the simulated circuit You designed and simulated an amplifier with gain close to the desired value, calculated values for the coupling capacitors, as well as the input and output impedances and presented your results in a nice way. Unfortunately your work on the bypass capacitor and the discussion are not sufficient. You designed and simulated an amplifier with the desired gain, calculated the coupling capacitors, and presented your results in a nice way. Additionally, you included all the required results concerning the bypass capacitor. However the discussion can be improved. Very nice work including all the calculations, and simulations. You also presented your results in a very understandable way, and extracted and discussed all the important parameters. OR: You designed and simulated an amplifier with gain close to the desired value, calculated values for the capacitors, and showed an increase of the gain if a bypass capacitor is used. Unfortunately your discussion is not sufficient. And you have to improve the way you present the results. Unfortunately your discussion is not sufficient. And you have to improve the way you present the results. OR: You designed and simulated an amplifier with the desired gain, calculated the coupling capacitors, and presented your results in a very good way. Also the discussion is appropriate. Nevertheless, a detailed description of the configuration using a emitter bypass capacitor is missing. OR: Very nice work including all the calculations, and simulations. Whereas also the internal emitter resistance was considered. Additionally the important parameters wave been determined and discussed. 80% 100% 60% You measured the transistor output characteristic for multiple different base currents, and presented the results in an understandable way. You also invested some effort in comparing your measurement results to the simulated results. Unfortunately the extraction of the performance parameters (gain, output resistance, and the transition between the linear and the active region) and the discussion is incomplete. OR: You measured the transistor output characteristic for multiple different base currents, and presented the results in a understandable way. Based on this data you also worked on the extraction of the important performance parameters (gain, output resistance, and the transition between the linear and the active region). Unfortunately the discussion, including a comparison between the measured and simulated performance, is incomplete. You successfully set up the circuit and justified your choice of resistors. You also measured all the currents and voltage levels and presented your results in an understandable way. Additionally, you compared your measurement results to your simulation results. However, there is no discussion and also no calculation of the efficiency. Very nice measurement, of the transistor output characteristic and presentation of the results. You also extracted the majority of the relevant performance parameters and compared them to the data sheet and your simulations. The discussion is not sufficient. Very nice measurement, of the transistor output characteristic and presentation and discussion of the results. The comparison between the simulated characteristic and the data sheet is appropriate. At the same time you have to improve your extraction of all the relevant performance parameters. The circuit is working, you measured all the important voltages and currents, and you explained your choice of resistors. Furthermore you also compared the results to your simulation. You made some efforts to calculate the circuit efficiency and to discuss your findings, Nevertheless this parts can still be improved. Very nice measurement and discussion, of the transistor output characteristic and presentation of the results. You also extracted the majority of the relevant performance parameters, and compared them to the data sheet and your simulations. Your circuit works and you included all the required information into your report (including comparison to your simulation). Additionally you also have a very good discussion of your results and calculated the circuit efficiency. OR: You successfully set up the circuit. You also measured all the currents and voltage levels presented your results in an understandable way, and included some calculation concerning the efficiency of the circuit. However, there is no in depth discussion and also no comparison between your measurement results to your simulation results. OR: The circuit is working, you measured all the important voltages and currents, and calculated the circuit efficiency. Furthermore you also compared the results to your simulation. You made some efforts to discuss your findings, Nevertheless this parts can still be improved. You set up a working common emitter amplifier and justified your choice of resistors and capacitors. You also characterized your circuit, present your results, and put some effort to extract the important parameters (upper and lower cut-off frequency, gain) and to compare the results to your simulation. Nevertheless, your discussion and your results concerning the bypass capacitor have to be improved. Your circuit works nicely and you acquired two good Bode plots (with and without the bypass capacitor). You justified your choice of resistors and capacitors. You also extracted the important parameters from the Bode plots and compare them to your simulation results. The only aspect you have to improve is your discussion. A very good demonstration and characterisation of a common emitter amplifier. You acquired two very good Bode plots (with and without the bypass capacitor) and discussed your results. You also justified your choice of resistors and capacitors, extracted the important parameters, discussed them and compare them to your simulation results. OR: You set up a working common emitter amplifier. You also characterized your circuit with and without bypass capacitor), present your results, and put some effort to extract the important parameters (upper and lower cut-off frequency, gain) and to compare the results to your simulation. Nevertheless, your discussion and the way you present your results has to be improved. OR: Your circuit works nicely and you acquired a good Bode plot. You justified your choice of resistors and capacitors. You also extracted the important parameters from the Bode plots, compare them to your simulation results, and included a good discussion. The only part you have to improve is the bypass capacitor related task. OR: A very good demonstration and characterisation of a common emitter amplifier. You determined the important performance parameters (with and without bypass capacitor) and discussed your results. Additionally, you also invested some effort to identify and discuss any unexpected behaviour. You also justified your choice of resistors and capacitors, extracted the important parameters, discussed them and compare them to your simulation results. You tried to set up an amplifier circuit, unfortunately you were not able to acquire any meaningful measurement. You tried to set up an amplifier circuit, unfortunately you were not able to measure any amplification. You were able to set up the circuit and to demonstrate some amplification. Unfortunately, there is no in depth characterisation of your amplifier. 0% 18% 35% 40% 60% 80% 100% Your report exhibits an appropriate structure. The way the content is presented is not very appealing. Your report exhibits a logical structure and is understandable. It would be good to improve the way the data is presented and to make the presentation more consistent OR: Your report exhibits is understandable. Also the way the data is presented is appropriate and the presentation is consistent. It would be good to improve the structure of the report. Maybe using the provided template could help. Your report is written in a very nice way. Also the presentation is appropriate. Your report is written and presented in a very nice, understandable and concise way. Your "report" just a collection of numbers. It is not understandable at all. Maybe you should think about using the provided template the next time. Report: Layout, structure, and understandability of the report 5% Template: Use of the provided Latex or Word template You have not used any of the templates 0% 18% Self-assessment: Use of provided table to asses own report Nothing at all Absolutely unrealistic 10% You set up the switching circuit and controlled the LED using a small base current. A better mark would require: the measurement of all the currents and voltage levels, and a justification of your choice of resistors. OR: You successfully simulated the LED circuits, and measured the important voltages and currents. At the same time your calculations to determine the resistor values are not clear. 100% No effort at all. 5% Self-assessment You set up a circuit to light up the LED. A better mark would require: switching operation, the measurement of all the currents and voltage levels, and a justification of your choice of resistors. You did set up the circuit on the ELVIS board and showed that the emitter current depends on the base current and the collector-emitter voltage. At the same time you should invest more effort in presenting your results, extracting the important performance parameters, and discussing the results. Also comparing the measured results to the data sheet and your simulation is an important point. You successfully simulated the LED circuit. Your calculations to determine the resistor values are clear. However you did not measure all the important voltages and currents. 80% You simulated a meaningful output characteristic, presented the results in an understandable way and extracted the majority of the relevant performance parameters (gain, output resistance, and the transition between the linear and the active region). You missed to include an in depth of your results and to compare them with the data sheet. OR: Very nice simulation, of the transistor output characteristic and presentation and discussion of the results. The comparison between the simulated characteristic and the data sheet is appropriate. At the same time you have to improve your extraction of all the relevant performance parameters. You successfully simulate the LED circuit, also your calculations to determine the resistor values are clear. Additionally, you measured the important voltages and currents. Unfortunately you did nit calculate the efficiency based on this simulation. OR: You successfully simulated the LED circuits, and extracted the important voltages and currents. You also used this values for some calculations concerning the efficiency of the circuit. At the same time your calculations to determine the resistor values are not clear. It looks like there is no underlying structure. Additionally, the way the content is presented is not very appealing. Maybe you should think about using the provided template the next time. You used a template, but not in a proper way. Problems are associated to the comments function, the references, or the example figures or text 35% You used one of the templates 40% 60% 5/5 80% 100% This makes sense This makes sense and is presented in a very nice and understandable way