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COLORADO STATE UNIVERSITY
ECE 332: ELECTRONIC PRINCIPLES II
HOMEWORK 10
1. A common source amplifier that can be represented by the equivalent circuit shown below
has 𝐶𝑔𝑠 = 2𝑝𝐹, 𝐶𝑔𝑑 = 0.1𝑝𝐹, 𝐶𝐿 = 2𝑝𝐹, 𝑔𝑚 = 4 𝑚𝐴/𝑉, and 𝑅′𝑠𝑖𝑔 = 𝑅′𝐿 = 20𝑘Ω. Find the
midband gain 𝐴𝑚 ,(i.e. DC gain), the input capacitance 𝐶𝑖𝑛 using the Miller approximation, and
an estimate of the 3-dB frequency 𝑓𝐻 due to 𝐶𝑖𝑛 and 𝑅′𝑠𝑖𝑔 .
2. A common source amplifier modeled with the equivalent circuit of the figure shown below is
specified to have 𝐶𝑔𝑠 = 2𝑝𝐹, 𝐶𝑔𝑑 = 0.1𝑝𝐹, 𝐶𝐿 = 2𝑝𝐹, 𝑔𝑚 = 4 𝑚𝐴/𝑉, and 𝑅′𝐿 = 20𝑘Ω. Find 𝐴𝑚 ,
𝑓3𝑑𝐵 due to total R and C at the output node, and gain-bandwidth produce, 𝑓𝑡 .
3. In the amplifier shown below, RD = 1k and CL = 1pF. Neglecting channel-length modulation
and other capacitances, determine the frequency at which the gain falls by 10% (about 1dB)
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4. Express the –3dB of the circuits shown below in terms of ro, gm of transistors and CL.
5. A two-stage cascade amplifier consisting two identical stages is shown below. RD=100K, CL
= 1pF, and gm = 1mS. Neglecting channel length modulation and other parasitic
capacitances, draw the Bode plot for Vout/Vin for the circuit.
6. Due to a manufacturing error, a parasitic resistance, RP, has appeared in series with the
source of the transistor as shown below. Ignore channel length modulation and other
parasitic capacitance, derive expressions for all poles and zeros in this circuit.
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