Question

The amplifiers X, Y and Z are connected in series. If the voltage gains of X, Y and Z are 10, 20 and 30, respectively and the input signal is 1 mV peak value, then what is the output signal voltage (peak value)

1. if dc supply voltage is 10V?
2. if dc supply voltage is 5V?

Answer 1

Total voltage amplification is defined as the ratio of output signal voltage and input signal voltage.

According to the problem. voltage gain in X, v_x = 10

Voltage gain in Y, v_y = 20

Voltage gain in Z, v_z = 30

ΔV₁ = 1 mV = 10^–3 V

And Total voltage amplification = v_x × v_y × v_z

ΔV₀ = v_x × v_y × v_z × ΔV₁ 

= 10 × 20 × 30 ×10^–3 = 6V

1. If DC supply voltage is 10 V, then output is 6 V, since the theoretical gain is equal to practical gain, i.e., the output can never be greater than 6 V.
2. If DC supply voltage is 5 V, i.e., V_cc = 5 V. Then, the output peak will not exceed 5 V. Hence V₀ = 5 V.