Question

Two amplifiers are connected one after the other in series (cascaded). The first amplifier has a voltage gain of 10 and the second has a voltage gain of 20. If the input signal is 0.01 volt, calculate the output ac signal.

Answer 1

Voltage gain of the first amplifier, V₁ = 10 
Voltage gain of the second amplifier, V₂ = 20 
Input signal voltage, V_i = 0.01 V 
Output AC signal voltage = V_o 
The total voltage gain of a two-stage cascaded amplifier is given by the product of voltage gains of both the stages, i.e., 
\(V = V_1 × V_2 \)
\(V = 10 × 20 = 200 \)
We have the relation:
\(V = \frac{V_0}{V_i}\)
\(V_0 = V × V_i \)
\(V_0 = 200 × 0.01 \)
\(V0 = 2 V\) 
Therefore, the output AC signal of the given amplifier is 2 V.