Question

Consider the op-amp configuration shown in the figure below :



Assume the op - amp circuit to be ideal, then which of the following statements is not correct about the circuit.

• A. The value of input is reduced by a factor (RC) and is integrated.
• B. The circuit introduces an input capacitance nearly equal to the value of capacitance C.
• C. The value of time constant for the circuit $\tau =RC$
• D. The circuit represents an integrator circuit with output having a phase shift of ${180}^{\circ }$

Answer 1

The correct option is B The circuit introduces an input capacitance nearly equal to the value of capacitance C.

The value of input capacitance is equal to
$C_{in}=C(1-A_v)\left(Mille{r}^{\prime }stheorem\right)$

$\because$ The op-amp is ideal and inverting,

$C_{in}\approx \infty$