Nanyang Technological University
School of Electrical & Electronic Engineering
E2002 Analog Electronics – Tutorial 6
1. The DC operating point of the common-emitter amplifier in Figure 1 has been
calculated in Question 3 of Tutorial 5 to be IC = 50 µΑ and VEC =10.86 V. The pnp
transistor Q1 has β = 100 and VA = 75V. Assume that the capacitors have infinite
value, what are the voltage gain, input resistance, output resistance and current gain if
VCC = VEE = 15 V, RI = 750 Ω, R1 = R2 = 200 kΩ, RL = 100 kΩ, RC = 100 kΩ, RE1 = 30
kΩ and RE2 = 250 kΩ.
(Ans: Av = −1.62, Rin = 96.86 kΩ, Rout ≈ 100 kΩ, Ai = −1.58 ).
What is the amplitude of the largest ac signal that can appear at the output that satisfies
the small-signal limit?
(Ans: 505.12 mV)
+VCC
RE2 C3
R2
RE1
RI C1
Q1
C2
+
vi +
− Rin
R1 RC RL vo
Rout −
−VEE
Figure 1
2. The DC operating point of the common-drain amplifier in Figure 2 has been calculated
in Question 4 of Tutorial 5 to be ID = 1.87 mΑ and VDS = 9.39 V. The n-MOS transistor
M1 has Kn = 1 mA/V2, VTN = 1 V and λ = 0.02 V−1. Assume that the capacitors have
infinite value, RI = 100 Ω, R1 = 1.2 MΩ, R2 = 910 kΩ, RS = 3 kΩ, RL = 250 Ω and VDD
= 15 V, calculate the voltage gain, input resistance and output resistance of the
amplifier.
(Ans: Av = 0.31, Rin = 517.54 kΩ, Rout = 434.6 Ω)
What is the maximum input signal amplitude for small signal operation?
(Ans: 556.52 mV)
1
VDD
R2
RI
M1
vi + +
− Rin R1 RL vo
RS
Rout −
Figure 2
