EE 333
Homework 4: Frequency Response
Spring 2025
For ALL the transistors in this homework (unless stated otherwise in the problem)
assume they have µnCox(W/L) = 4mA/V2, Vt= 0.3V,
1. Refer to Figure 1: Rsig = 0.2 MW, RG = 2 MW, gm = 2 mA/V, RD = 20 kW and RL = 10 kW.
a. Find AM
b. Design the coupling and bypass capacitors to locate the three low-frequency
poles at 100 Hz, 10 Hz, and 1 Hz.
Figure 1
2. Refer to Figure 2: Assume the current source is
ideal and ignore early voltage eRect. Using the
SCTC method, derive the lower 3-dB frequency fL
and the midband gain AM.
Figure 2
3. Refer to Figure 3: Rsig = RL = 2 kW, RC = 5 kW, RB = 47 kW, gm = 2 mA/V, RD = 20 kW and b
= 100. Cµ = 0.8 pF and fT = 600 MHz. Assume coupling capacitors are very large.
a. Calculate the dc collector current of the transistor.
b. Calculate the midband gain.
c. Use Miller’s approximation approach to find the input resistance of the
circuit.
d. Estimate the upper 3-dB frequency, fH
Figure 3
4. Refer to Figure 4. Given the transistors have b = 100, VA = 100 V and Cµ = 0.5 pF and
fT = 200 MHz
a. Calculate the input resistance Rin and the circuit midband gain.
b. Find an estimate of upper 3-dB frequency fH and which capacitor dominates?
Figure 4
5. Refer to Figure 5. Given I = 200 μA and VOV = 0.2 V, Rsig = 100 kW, RD = 50 kW, Cgs = 4
pF, and Cgd = 0.5 pF. Find the dc gain, the high-frequency poles, and an estimate of
fH .
Figure 5
6. Refer to Figure 6. For BJT (a), let β = 100, Cμ = 2 pF, and fT = 400 MHz, and neglect ro.
For MOSFET (b), Each of Q1 and Q2 is operated at an overdrive voltage of 0.2 V, and VA
=10 V. The transistor capacitances are as follows: Cgs = 20 fF, Cgd = 5 fF, and Cdb = 5
fF. The signal-source resistance Rsig = 10 k. Calculate the midband gain AM and the 3dB frequency fH.
(b)
(a)