## Description

• Bipolar Junction Transistors

1. What are the functions of capacitors C1, C2, and C3 in the follow Figure 1, (b)

What is the magnitude of the signal voltage at the emitter of Q1, (c) What kind

of transistor it is?

Figure 1: BJT Transistor

1

2. Draw the dc equivalent circuit and find the Q-point for the amplifier in Fig. 2.

Assume βF = 75, VCC = 10 V, -VEE = -10 V, RI =1kΩ, R1 = 5 kΩ, R2 = 10

kΩ, R3 = 24 kΩ, RE = 4 kΩ and RC = 6 kΩ.

Figure 2: BJT Transistor

3. Draw the dc equivalent circuit and find the Q-point for the amplifier in Fig. 3.

Assume βF = 100, VCC = 9 V, -VEE = -9 V, RI = 1 kΩ, R1 = 43 kΩ , R2 = 43

kΩ, R3 = 24 kΩ and RE = 82 kΩ.

Figure 3: BJT Transistor

2

4. Draw the dc equivalent circuit and find the Q-point for the amplifier in Fig. 4.

Assume Kn = 400 µA/V2

, VT N = -5 V, VDD = 16 V, RG = 10 MΩ , RD = 3.9

kΩ, RI = 10 kΩ, R1 = 2 kΩ, RS = 1 kΩ, R4 = 1 kΩ and R3 = 36 kΩ.

Figure 4: BJT Transistor

5. What is the voltage gain of the amplifier in Fig. 5? Assume Kn = 0.500 mA/V2

,

VT N =1V and λ = 0.0133V−1

.

Figure 5: BJT Transistor

6. Calculate rd for a diode with VD = 0.6 V if IS = 8 fA. (b)What is the value of rd

for VD = 0V? (c) At what voltage does rd exceed 1012 Ω?

3

7. The ac equivalent circuit for an amplifier is shown in Fig. 6. Assume the capacitors have infinite value, RS =750 Ω, RB =100 kΩ, RC = 100 kΩ, and R3 = 100

kΩ. Calculate the voltage gain and input resistance for the amplifier if the BJT

Q-point is(40 µA,10V). Assume β0 = 100 and VA = 75V.

Figure 6: BJT Transistor

4