Question

In the circuit shown below, the small signal parameter $R_0$ for the amplifier given below is



[Assume that the h-parameters of the transistor are] $h_{\propto }=1k\Omega ,h_{fk}=100,h_{ae}=40\mu \mho and{h}_{rc}=0$

• A. 1.79 k$\Omega$
• B. 0.98 k$\Omega$
• C. 1.2 k$\Omega$
• D. 2.42 k$\Omega$

Answer 1

The correct option is A 1.79 k$\Omega$

The ac equivalent circuit for the amplifer is



Output impedance $R_O=\left(R_{F2}\right)||\left(R_C\right)||\left(\frac{1}{h_{oc}}\right)$

$R_O=\frac{1}{\frac{1}{50k}+\frac{1}{2k}+\frac{1}{25k}}=1.785k\Omega$