Question

Problem 2 (10 points) In the amplifier shown in Fig. 2(a), assume Fig. 2(b) that I4 is ideal. Do not ignore the ro of the transistors for this problem, but you can assume that Ri is much smaller than any transistor o I1 and I2 ideal current sources. Also, assume in are (a) Find the small signal differential gain out/vdm of the Fig. 2(a) amplifier in terms of the appropriate small-signal parameters. Then express your answer in terms of appropriate dc voltage biasing and other relevant parameters (b) By what factor will the gain of the Fig. 2(a) amplifier change if the series connection of capacitor CB and resistor R (shown in Fig. 2(c)) is connected directly between Vt and ground? Assume that CB is very large so that it presents a very small impedance for the frequencies of interest out (c) We now connect the input of the Class A output stage shown in Fig. 2(b) to the output of the Fig. 2(a) amplifier. Find the overall differential gain out/Vdm of this circuit in terms of small-signal parameters when Vout is left open-circuited (d) By what factor will the gain of the amplifier-output stage combination change if the Fig. 2(c) load is connected between Vout and ground? DD DD I3 out out + 4 Va Out CB 2B (b) (a) Figure 2 wl HIG

Answer 1

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