Experiment # 1

_{Experiment # 5

Bipolar Junction Transistors

Biasing & the BJT inverter

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

Figure # 1

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

Figure # 2

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

Build and fully test the circuit shown in Figure #1. Measure VE, VB, VC, VBE, IB, IE, and IC.

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.

By applying a sinusoidal signal such that the small signal approximation holds, measure:

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

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

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

4.- Conclusion

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.}