Chapter 11, Problem 11.6TYU

The parameters of the diff-amp shown in Figure 11.2 are $V^{+}=5\text{V}$ $V^{-}=-5\text{V},I_Q=0.4\text{mA},$ and $R_C=10\text{k}\Omega .$ The output resistance of the constant-current source is $R_o=100\text{k}\Omega .$ The transistor parameters are $\beta =150$ $V_{BE}(\text{on})=0.7\text{V},$ and $V_A=\infty .$ (a) Determine the dc input base currents. (b) Determine the differential signal input currents if a differential-mode input voltage $v_d=10\sin \omega t\text{mV}$ is applied. (c) If a common-mode input voltage $v_{cm}=3\sin \omega t\text{V}$ is applied, determine the common-mode signal input base currents. (Ans. (a) $I_{B1}=$ $I_{B2}=1.32\mu \text{A},(\text{b})I_b=0.256\sin \omega t\mu \text{A},(\text{c})I_b=0.0993\sin \omega t\mu \text{A})$ .