Question 11.3: Simplified Model for an Amplifier Cascade Find the overall s...

The voltage gain of the first stage, accounting for the loading of the second stage, is

A_{v1}=A_{voc1}\frac{R_{i2}}{R_{i_2}+R_{o1}}=150

With an open-circuit load, the gain of the second stage is

A_{v2}=A_{voc2}=100

The overall open-circuit voltage gain is

A_{voc}=A_{v1}A_{v2}=15\times 10^3

The input resistance of the cascade amplifier is

R_i=R_{i1}=1\mathrm{~M}\Omega

and the output resistance is

R_o=R_{o2}=100\Omega

The simplified model for the cascade is shown in Figure 11.7.