HW_20 - I = 20 µ A and V DD = V SS = 5 V. Neglecting the...

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EE 438 Homework #20 The two BJT’s in the differential amplifier circuit in Fig. 1 are identical. Their parameters are I S = 10 -15 A, β = 100 , V A . The parameters for the MOSFETs in the differential amplifier circuit in Fig. 2 are NMOS: k n = 20 µ A/V 2 , W = 200 µ m, L = 10 µ m, V tn = 1 V, λ = 0.04 V -1 PMOS: k p = 10 µ A/V 2 , W = 100 µ m, L = 10 µ m, V tp = -1 V, = 0.04 V -1 1. In the differential amplifier circuit of Fig. 1 let I = 1 mA, R C = 5k , R E = 200 , and V CC = V EE = 5 V. Perform a DC analysis using the expression (use V T BE V V S C e I I / = T = 25.88 mV) to find the voltages (a) V E1 , (b) V X , and (c) V C1 . Also, determine (d) g m , and (e) r e . 2. Use a small signal equivalent of the circuit in Problem 1 with the values of g m and r e determined in that problem to find (a) the differential voltage gain, 2 1 2 1 i i c c v v v A = v v , and (b) the differential input resistance, R id . 3. In the MOSFET differential amplifier circuit of Fig. 2 let
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Unformatted text preview: I = 20 µ A and V DD = V SS = 5 V. Neglecting the channel length modulation effect perform a DC Analysis of the circuit to find (a) V GS 3 , and (b) V GS 1 . Also find the small signal parameters (c) g m1 = g m2 , (d) g m3 =g m4 , and (e) r o1 = r o2 = r o3 = r o4 4. Use a small signal equivalent of the circuit in Problem 3 with the values of g m and r o determined in that problem to find the differential voltage gain, 2 1 i i o v v v A − = v . Use the approximate method discussed in class to simplify the analysis of the equivalent circuit. Fig. 1. BJT Differential Amplifier R C R C R E R E v i1 I v i2 V CC Q 1 Q 2 v C1 v C2 v E1 v E2 v X V EE _ + _ + Fig. 2. CMOS Differential Amplifier with Current Mirror Load Q 1 Q 2 Q 3 Q 4 V DD I v X v i1 v i2 V SS _ + _ + v o...
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This note was uploaded on 10/26/2009 for the course EE 438 taught by Professor Cardwell during the Spring '08 term at University of Texas at Austin.

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HW_20 - I = 20 µ A and V DD = V SS = 5 V. Neglecting the...

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