Equipment:
You must make up a complete equipment list and have your instructor review it before you start.
 

Objectives:

• To verify the operating point for a MOSFET biasing network

• To verify the small signal performance for a given Common Source amplifier: RIN, ROUT, Av, Ai , maximum input amplitude without distortion vin max , etc.

• To verify the small signal performance for a given Common Drain amplifier: RIN, ROUT, Av, Ai , maximum input amplitude without distortion vin max , etc.

• To establish the relationship between the voltage gain and the load

Figure # 1

1.- (HW) DC Analysis

1. Analyze the circuit shown in Figure # 1 (use nominal values) and find VGG, VG, VS, VD, and ID (assume VDD = 30 Volts DC, K = 40 mAmp/Volt , Vth = 1.73 V).

 
2. Assemble this circuit on ORCAD and perform a bias point detail analysis. Show the appropriate voltages and current on the schematic.

1. Build and fully test the circuit shown in Figure #1. Measure  VG, VS, VD, and ID.

For the circuit in Figure # 1:

1. Assuming that this circuit is operated in Common Source (with shorting capacitor on the Source):

 
1. Find ROUT, RIN, Avo, Av @RL=ROUT and Ai@ RL=ROUT.  Label this as "Analysis for Common Source"
2. Also, find the maximum input voltage vin max that the amplifier can accept before the output distorts (loaded and unloaded).
3. Use ORCAD to find Av@RL=ROUT and Ai@RL=ROUT.

 
2. Assuming that this circuit is operated in Common Drain (with shorting capacitor on the Drain):

 
1. Find ROUT, RIN, Avo, Av @RL=ROUT and Ai@RL=ROUT. Label this as "Analysis for Common Drain"
2. Also, find the maximum input voltage vin max that the amplifier can accept before the output distorts (loaded and unloaded).
3. Use ORCAD to find Av@RL=ROUT and Ai@RL=ROUT.

4.- Small Signal Verification

Build and fully test the circuit shown in Figure #1. By applying a sinusoidal signal such that the small signal approximation holds, measure:

1. For the CSC:

 
1. RIN (input impedance) and ROUT (output impedance) of the assembled circuit.
2. Voltage gain Av the assembled circuit for the unloaded case (RL really large).  Print the output plot and label it as "Avo for Common Source"
3. Voltage Gain for RL equal to 2*ROUT, ROUT, ROUT /2, and ROUT /4.  DO NOT print the output plots.  Put the corresponding values of Av in a table.  Label it as "Table 1 - Common Source Av for various RL"
4. Find the maximum input voltage that the amplifier can accept before the output distorts @ RL = ROUT. Plot the output signal and the corresponding input.
5. Determine the phase relationship between the input and output voltages.
6. Compare the measured results to your analysis calculations.

 

 
 
 

2. For the CDC:

1. RIN (input impedance) and ROUT (output impedance) of the assembled circuit.
2. Voltage gain Av the assembled circuit for the unloaded case (RL is really large).  Print the output plot and label it as "Avo for Common Drain"
3. Voltage Gain for RL equal to 2*ROUT, ROUT, ROUT /2, and ROUT /4.  DO NOT print the output plots.  Put the corresponding values of Av in a table.  Label it as "Table 2 - Common Drain Av for various RL"
4. Find the maximum input voltage that the amplifier can accept before the output distorts @ RL = ROUT. Plot the output signal and the corresponding input.  Label the plot appropriately.
5. Determine the phase relationship between the input and output voltages.

Compare the measured results to your analysis calculations.

5.- Conclusion

   a.Considering that these amplifiers are quite typical, what can you say about Rin, Rout, and the Av for the Common Source and Common Drain amplifiers.

   b.Based on your observation, what are the primary differences between BJT and MOSFET Amplifiers?

   c.Which configuration is better for the voltage amplification stage in your audio mixer project: Common Emitter or Common Source?  Explain.