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 Beta Stabilized Biasing Network

• To verify the operation of BJT inverter

• To verify the voltage gain Av of a CEC

• To verify the voltage gain Av of a CBC

• To verify the voltage gain Av of a CCC

1.- (HW) Analysis

Analyze the circuit shown in Figure # 1 (use nominal values) and find VBB, VE, VC, VB ,VBE, VCE, , IB, IE, IC, RB, (assume VCC = 30 VDC, b = 180, VT = 26 mV).

 

Assemble this circuit on SPICE and perform a bias point detail analysis. Show the calculated voltages and currents by appropriately placing IPROBEs and VIEWPOINTs on your schematic.

 

Repeat part b) but for the value of  b equal to 10. Compare your results with those obtained in b).

2.- (HW) Simulation
 
 

Use SPICE to simulate the BJT inverter shown in Figure # 2. Plot the value of the output voltage Vo vs. the input voltage Vi. V1 must remain at 5 VDC while V2 varies from 0 to 5 Volts. Indicate in the plot when the BJT is in the saturation, linear, or cut-off region.
 
 

3.- Verification

1. Build and fully test the circuit shown in Figure #1. Measure VE, VB, VC, VBE, IB, IE, and IC.
2. Build and fully test the circuit shown in Figure #2. Measure Vo for Vi varying from 0 to 3 Volts with increments of 0.2 Volts. Plot the results.
3. By applying a sinusoidal signal such that the small signal approximation holds, measure:

1. Voltage gain Avo (unloaded) for the circuit in Figure # 1 when operating in CEC.
2. Voltage gain Avo (unloaded) for the circuit in Figure # 1 when operating in CBC.
3. Voltage gain Avo (unloaded) for the circuit in Figure # 1 when operating in CCC.

Hand in the output plots for each configuration.

Hint: Connect a large capacitor between VCC and ground in order to remove all the noise from the source. The noise is amplified and mixes with the output due to the input AC signal Vs.
 
 
 

4.- Conclusion

Plot the PC-Spice results and the measured results of the BJT inverter on one plot & compare these results. Write a clear conclusion establishing the most important facts about the operation of the BJT inverter, the beta stabilized biasing network and particularly its operation in the different configurations.