Question

3. In the circuit shown below, the differential pair (Mand M2) is biased with a current miror that consists of M3, M and Rref. The circuit parameters are: VDD-3 V, Rre/-15 ka, RD = 20 ka, and RL-40 kn. The transistors 25 M, and M, are identicalwith()M and M, are identical with (The oh M and M4 are identical with = ·The other transistor parameters are: indox-: 0.1 m1A/V2,VTN-0.5 V, γ-0 (body effect coefficient) and λ 0 (channel length modulation effect parameter). (a) Find the values of IREF and V. (6 marks) (b) Let vi 2VcM. Find the minimum value of VcM such that M, M2 and M4 all operate in the saturation region. (4 marks) v2 Vid, where vid is a smal signal. The common-mode value of v and v2 is selected such that (c) Let v M1, M2 and M4 operates in the saturation region. Draw a small-signal AC equivalent circuit of the entire circuit. (5 marks) when the output is taken differentially as (d) Based on the result in (d), find the voltage gain Ad Did a a. (5 marks) d1 d2

Answer 1

3 15K b) 1-26 Ahan 126-0.5 0-16 Lo- 0116mA 0.84 m A Foh ON Con 1.84

.V2 0 hou dt Rp RD d2 2 1써 Due to Vid