Unformatted text preview: Figure 3: V533 : Rt ... ma 3. For the transistor circuit below (Figure 4): a. What value of Vin causes the transistor to enter the forward active region? b. We want to use this circuit for small signal analysis using a DC bias of 3V to offset
the signal. What will the base current be for this VDC? c. To make the most use of the gain of this circuit, we want to DC bias to lie in the
middle of the forward active region of the transistor. What value for RC will allow
this to happen? (1. Solve for Rat and sketch the small signal model for the circuit. e. What is the gain of the small signal model? Figure 4: Va: :Lov'
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‘RE 4. In the system below: a. We are modulating two radio signals x1(t) and X2(t) by carrier signals, combining
them and transmitting them, and then recovering them through demodulation and a low
pass filter. Sketch the frequency spectrum V(f), the combined spectrum, and X1(i) and
X203, the recovered signals. b. If we attach the following filter to the outputs of our system, and the ﬁlter is to be
built of a signal with triangular frequency spectrum A(f) sampled at fg. How could we
construct the ﬁlter such that the output of the ﬁlter will be equal to the input of the filter? F i gure 5:
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 Fall '07
 Williams

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