Experiment # 6
Bipolar Junction Transistors
Common Emitter (CE) & Common Collector (CC)
Equipment: You must make up a complete equipment list and have your instructor review it before you start.
Objectives:
- To verify the small signal performance for a given CEC amplifier: RIN, ROUT, Av, Ai , maximum input amplitude without distortion vin max , etc.
- To verify the small signal performance for a given CCC amplifier: RIN, ROUT, Av, Ai , maximum input amplitude without distortion vin max , etc.
- To design a CEC amplifier according to a set of specifications
- To design a CCC amplifier according to a set of specifications
- To establish the relationship between the voltage gain and the load
Figure # 1
1.- (HW) Analysis
The circuit above was analyzed in lab # 5. With the values obtained for the bias currents and voltages:
- Assuming that this circuit is operated in CEC (with shorting capacitor):
- Find ROUT, RIN, Avo, Av (RL=ROUT) and Ai (RL=ROUT).
- Also, find the maximum input voltage vin max that the amplifier can accept before the output distorts (loaded and unloaded).
- Assuming that this circuit is operated in CCC (with shorting capacitor):
- Find ROUT, RIN, Avo, Av (RL=ROUT) and Ai (RL=ROUT).
- Also, find the maximum input voltage vin max that the amplifier can accept before the output distorts (loaded and unloaded).
2.- Verification
Build and fully test the circuit shown in Figure #1. By applying a sinusoidal signal such that the small signal approximation holds, measure:
- For the CEC:
- RIN (input impedance) and ROUT (output impedance) of the assembled circuit.
- Voltage gain Av the assembled circuit for the unloaded case, and for RL equal to 2*ROUT, ROUT, ROUT /2, and ROUT /4
.
Find the maximum input voltage that the amplifier can accept before the output distorts (loaded case). Plot the output signal and the corresponding input.
Determine the phase relationship between the input and output voltages.
Compare the measured results to your analysis calculations.
For the CCC:
- RIN (input impedance) and ROUT (output impedance) of the assembled circuit.
- Voltage gain Av the assembled circuit for the unloaded case, and for RL equal to 2*ROUT, ROUT, ROUT /2, and ROUT /4
.
Find the maximum input voltage that the amplifier can accept before the output distorts (loaded case). Plot the output signal and the corresponding input.
Determine the phase relationship between the input and output voltages.
Compare the measured results to your analysis calculations.
3.- (HW) Design
Design a Beta-Stabilized capacitively coupled Common Emitter voltage amplifier (with shorting capacitor) similar to the one shown in Fig # 1. Use SPICE to verify that all the specifications have been achieved..
Design Specifications of the Amplifier
VCC 30 VDC ± 0.5 VDC
Av -20
RL 15 k
W
RIN 4 k
W
4.- Assembly, Test and Verification of Specifications
Build and test your design. Measure and verify that your design meets all the given specifications.
- Measure VBE, VE, VB, , VCE, IB, IE, and IC with no input.
- Measure Av, Rin (input impedance) and Rout (output impedance) of the assembled circuit.
- Find the maximum input voltage that the amplifier can accept before the output distorts.
- Measure the phase relationship between the input and output voltages.
5.- (HW) Design
Design a Beta-Stabilized capacitively coupled Common Collector voltage amplifier (with shorting capacitor) similar to the one shown in Fig # 1. Use SPICE to verify that all the specifications have been achieved.
Design Specifications of the Amplifier
VCC 30 VDC ± 0.5 VDC
Ai 15 @ 10 kHz
RL 510
W
6.- Assembly, Test and Verification of Specifications
Build and test your design. Measure and verify that your design meets all the given specifications.
- Measure VBE, VE, VB, , VCE, IB, IE, and IC with no input.
- Measure Avo, Av, Rin (input impedance) and Rout (output impedance) of the assembled circuit.
- Determine the current gain Ai.
- Find the maximum input voltage that the amplifier can accept before the output distorts.
- Measure the phase relationship between the input and output voltages.
5.- Conclusion
- Considering that these amplifiers are quite typical, what can you say about Rin, Rout, and the Av for the CEC amplifier, and for the CBC.
- Why is there always a big difference between the value the function generator was set for and the actual input signal?
- Compare the measured results to your design calculations and specifications. Explain any and all differences!
- etc.