GATE 2024 IN – Question 29
The figure shows the readout circuit of a piezoelectric sensor. A generated charge $q_p$ produces a change of $-2$ V at $V_x$. The corresponding change in output voltage $V_{out}$ is ______ V (nearest integer). All components are ideal.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: -3 to -3
Explanation
The opamp keeps its inverting input at virtual ground. Charge balance at the floating junction gives $100(V_x-0)+200(V_x-V_{out})=0$, with capacitances in pF.
Thus $V_{out}=1.5V_x$ and $\Delta V_{out}=1.5(-2)=\boxed{-3}$ V.