Consider the circuit in Figure P13.60. A JFET diff-amp input stage drives a bipolar Darlington second stage. The p-channel differential pair \(J_{1}\) and \(J_{2}\) are connected to the bipolar active load transistors \(Q_{3}\) and \(Q_{4}\). Assume JFET parameters of \(V_{P}=3 \mathrm{~V}, I_{D S S}=200 \mu \mathrm{A}\), and \(\lambda=0.02 \mathrm{~V}^{-1}\). The bipolar transistor parameters are \(\beta=100\) and \(V_{A}=50 \mathrm{~V}\).

(a) Determine the input resistance \(R_{i 2}\) to the second stage.

(b) Calculate the small-signal differentialmode voltage gain of the input stage. Compare this value to the 741 and CA3140 input stage results.

Transcribed Image Text:

J V+ V+ = 200 R2 V+ Q5 Q6 Q3 Q4 RE=0.3 k Figure P13.60 L= 200 A