Help on the circuit with Opamp

[FvM]

varunkant2k showed two different cases, which are you referring to? One is 1.5V pure DC, I explained the result in post #17. In fact, a diode has some (very small current) at zero diode voltage as well.

In the second one, 1V DC + 0.5 sine is applied. Here the capacitor is charged to Vpeak - diode forward voltage. The diode capacitance also couples a small AC amount.

 

[goldsmith]

see below , please :

when the input is one volts the out put is one volts .
Thanks
Goldsmith

 

[FvM]

Yes, because the capacitor has inifinite time to settle to Vin. For a realistic simulation, apply a 0 to 1 V step in transient simulation and watch how long it takes for the voltage to rise to about 1 V.

 

[varunkant2k]

FVM explained it already. My simulation valid for fixed dc voltage storage at the capacitor. Off state Diode in metal is nothing but a very high resistive path to capacitor, that is sufficient to store the dc state of signal to capacitor, but transient signal value ( having variation in average signal value) may take a longer value to store at capacitor.
That is why the condition I told "if loading is negligible".