Chapter 6, Problem 6.5EP

For the circuit in Figure 6.31, let $R_E=0.6\text{kΩ}$ , $R_C=5.6\text{kΩ}$ , $\beta =120$ , $V_{BE}\text{(on)}=0.7\text{V}$ , $R_1=250\text{kΩ}$ , and $R_2=75\text{kΩ}$ . (a) For $V_A=\infty$ , determine the small−signal voltage gain $A_{\upsilon }$ . (b) Determine the input resistance looking into the base of the transistor. (Ans. (a) $A_{\upsilon }=-8.27$ , (b) $R_{ib}=80.1\text{kΩ}$ )

Figure 6.31 Figure for Exercise Ex6.5