Chapter 4, Problem 4.57P

A source−follower circuit with a saturated load is shown in Figure P4.57. The transistor parameters are $V_{TND}=1\text{V}$ , $K_{nD}=1{\text{mA/V}}^{\text{2}}$ for $M_D$ , and $V_{TNL}=1\text{V}$ , $K_{nL}=0.1{\text{mA/V}}^{\text{2}}$ for $M_L$ . Assume $\lambda =0$ for both transistors. Let $V_{DD}=9\text{V}$ . (a) Determine $V_{GG}$ such that the quiescent value of ${\upsilon }_{DSL}$ is 4 V. (b) Show that the small−signal open−circuit $\left(R_L=\infty \right)$ voltage gain about this Q−point is given by $A_{\upsilon }=1/\left[1+\sqrt{K_{nL}+K_{nD}}\right]$ . (c) Calculate the small−signal voltage gain for $R_L=4\text{k}\Omega$ .

Figure P4.57