Need help on question C - G
11.65 The feedback transresistance amplifier in Fig.P11.65 utilizes two identical MOSFETs biased by ideal current sources I = 0.3 mA. The MOSFETs are sized to operate at Vov=0.15 V and have V = 0.35 V and Vd = 6 V. The feedback resistance RF=20 kΩ.
a) If I has a zero dc component, find the dc voltage at the input, at the drain of, and at the output.
b) Find gm and ro of and c) Replacing the MOSFETs with their equivalent circuit models, provide the A circuit and derive an expression for A in terms of gm1, ro1, gm2, ro2, and R.
d) What is? Give an expression for the loop gain A and the amount of feedback (1 + A)
e) Derive an expression for Af.
f) Derive expressions for R, Rin, Ro, and Rout
g) Evaluate A, , A, A, R, R., Rin, and Rout for the component values given.
Answers:
a) +0.5 V, +1.0 V, +0.5 V;
b) 4 mA/V, 20 kΩ;
c) A = -gm1ro1RF / (RF||ro2 + 1/gm2);
d) -1/RF; m1ro1(Rp||ro2) + 1/gm2;
e;
f) RF(RF||ro2) + 1/gm2 + (gm1ro1)(RF||ro2) RF / [1 + gm1ro1(RF||ro2) + 1/gm2];
g) -1561 kΩ, -0.05 mA/V, 78 - 19.8 kΩ, 20 kΩ gm1ro1(Rp||ro2) + 1/gm2 244, 253, 3.1
