Chapter 11, Problem 11.7TYU

The circuit parameters of the diff-amp shown in Figure 11.19 are $V^{+}=3\text{V},V^{-}=-3\text{V},I_Q=0.40\text{mA},$ and $R_D=7.5\text{k}\Omega .$ The transistor parameters are $V_{TN}=0.5\text{V},k_n^{\prime }=100\mu \text{A}/{\text{V}}^2,$ and $\lambda =0.$ (a) Design the transistor $W/L$ ratio such that the differential voltage gain is $A_d=12.$ (b) What is the maximum positive common-mode voltage that can be applied such that the transistors remain biased in the saturation region. (Ans. (a) $W/L=256,$ (b) $v_{cm}=2\text{V}$ ).