Question

Question 4: Figure 4 In the series-shunt feedback amplifier shown in Figure 4, the transistors are biased with ideal current-sources 1, 0.1mA, 12 1mA, the devices operate with VE0.7V and t = 100. The input signal V, has a zero DC component. Resistances are (a) If the open loop gain is large, what do you expect the closed-loop gain A, -V/V, to be? Give both an expression and its approximate value (b) Find the DC emitter current in each of Q1 and Q2. Also find the DC voltage at the emitter of Q2. (c) Sketch the open loop circuit without the DC sources. Derive expressions for A, Ri, and Ro, and find their values. (d) Find the closed-loop gain Ay- the input resistance Rin, the output resistance Rout. By what percentage does the value of A, differ from the approximate value found in (a)?

Answer 1

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