Question

The feedback used in the circuit shown in figure can be classified as,

• A. shunt-shunt feedback
• B. series-series feedback
• C. shunt-series feedback
• D. series-shunt feedback

Answer 1

The correct option is D series-shunt feedback

(c)
The given voltage amplifier utilizes two MOSFET amplifier stages in cascade. The output voltage $V_0$ is sampled by the feedback network composed of the voltage divider ($R_1,R_2)$ and the feedback signal $v_f$ is fed to the source terminal of Q1. The subtraction is implemented by applying $v_s$ to the gate of $Q_1$ and $v_f$ to its source, with the result that the signal at this amplifier input
$V_i=V_{g^s}$ = $V_s-V_f$ .
To ascertain that the feedback is negative let $V_s$ increase.
The feedback network will then cause $V_f$ to increase .