Chapter 3, Problem 3.55P

All transistors in the current−source circuit shown in Figure 3.49(b) in the text have parameters $V_{TP}=-0.4\text{V}$ , ${k^{\prime }}_p=50\mu {\text{A/V}}^2$ , and $\lambda =0$ . The bias sources are $V^{+}=5\text{V}$ and $V^{-}=-5\text{V}$ . The currents are to be $I_{Q2}=200\mu \text{A}$ and $I_{\text{REF2}}=125\mu \text{A}$ . For $M_B$ , we require $V_{SDB}\left(\text{sat}\right)=0.8\text{V}$ , and for $M_A$ , we require $V_{SDA}=4\text{V}$ . Transistors $M_A$ and $M_B$ are matched. (a) Find the W/L ratios of the transistors. (b) Find the value of $R_D$ .