consider the following parameters for the transistors in fig 1 vds sat

Question

Consider the following parameters for the transistors in fig 1. VDS,sat_n=VDS, sat_p=0.25 V,
Vtn=0.972 V, Vtp|=0.748 V, unCox=4.954e-05 A/V² and upCox=2.549e-05 A/V². (Assume long
channel devices).
a) [2 pts.] Consider the CMOS input stage shown in fig 1. (loads of diff pairs are not shown).
What Vds value would you choose for MR2 and Vsd for MRI for max headroom operation?
b) [8 pts.] Based on your Vds and Vsd choices in part (a), find an appropriate voltage range for
each of the bias voltages Vbl & Vb2 (al<Vbl<bl & a2<Vb2<b2) such that the tail current
devices operate properly, i.e. find al, bl, a2, b2.
c) [10 pts.] Modify the ranges that you got in part (b) to be 1.15*al<Vbl<0.85*b1 and
0.85*a2<Vb2<1.15*b2, and based on these new ranges, size (find W/L) MR1 and MR2 such
that their drain current is 10μA, choose Vbl and Vb2 such that your W/L choices are
optimized for the best CMRR response vs. frequency response.
d) [10 pts.] Size (find W/L) M1, M2, M3 and M4 such that the maximum value of the total gm of
this stage is 100 µA/V. Assume that gm of the n-diff pair is equal to gm of the p-diff pair.
e) [4 pts.] State one benefit of such a circuit over regular diff amps.