Download ENEE 611 Final Exam Part I. The following questions refer to the

ENEE 611
Final Exam
Part I. The following questions refer to the circuit in Figure 1. Assume you know β, Iss,
Vt, for all transistors, R1, R2, R3, R4,Vcc and Vss. The answers should be algebraic
expressions. (Make sure your answers are in terms of known values.)
1. Obtain an expression for the small signal gain of this circuit at low frequencies.
2. For such a configuration, when there is no input signal, we would like the output to be
at a DC value of 0V, why? (Answer in one or two sentences.)
3. Obtain an expression for R3 that would give a DC output value of 0V.
4. Show how you would connect a series-shunt feedback loop to this circuit.
5. Describe qualitatively why the connection you chose gives negative feedback.
6. Obtain an expression for the loaded open loop gain of this circuit that includes the
feedback loop.
7. Obtain an expression for the loaded closed loop gain of this circuit.
8. Provide expressions for the input and output resistances of this circuit with feedback
present.
9. If this feedback circuit is driven by a small signal AC voltage source of with source
resistance Rs, give an expression for the voltage at the output.
10. Show how you would connect a shunt-shunt feedback loop to this circuit.
Vo
Figure 1