ECE 265A
Homework #2
(TA: [email protected])
Due Thursday Feb. 18, 2010 InClass. No late homeworks accepted.
1)
40 pts. Below is an
ideal
voltage amplifier that has been characterized with
uncorrelated noise sources,
a
v
and
a
i
. You want to build a transimpedance
amplifier by placing a shunt resistor across the amplifier. Assume that the input of
the voltage amplifier is a common source NMOS device. You may solve the
problem using any technique discussed in class.
First, let us consider how this amplifier works.
a.
Calculate the transimpedance transfer function (the ratio of the output
voltage to input current) in terms of the Rf, Av, and Cgs.
What happens to
the midband transimpedance for large Av? What happens to the pole for
large Av? (8)
b.
Calculate the input impedance (the transfer function of input current to
input voltage. What is the response for large Av? (5)
Now let us consider how noise in this amplifier works.
c.
Derive a new input referred noise model for the shuntfeedback amplifier.
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 '09
 Amplifier, Volt, Electronic amplifier, Common source, Common emitter, minimum noise figure, optimum source admittance, noise correlation chain

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