Chapter 11, Problem 11.9TYU

The diff-amp in Figure 11.19 is biased at $I_Q=100\mu \text{A}.$ The transistor parameters are $k_n^{\prime }=100\mu \text{A}/{\text{V}}^2$ and $W/L=10.$ (a) If the output resistance of the current source is $R_o=1\text{M}\Omega ,$ determine the common-mode rejection ratio CMRR ${}_{\text{dB}}$ . (b) Determine the required value of $R_o$ such that ${\text{CMRR}}_{\text{dB}}=80\text{dB}$ . (Ans. (a) CMRR ${}_{\text{dB}}=50\text{dB},$ (b) $R_o=31.6\text{M}\Omega$ ).