Four transistor cell of Rectifiers

Hi,

Attached is the circuit for rectifier and input,output waveform of the same.
I have given peak-peak of 1.5V to the rectifier as input and the output is measured at the drain's of PMOS as High and drain's of NMOS as low.
When I slowly increased the cap from 1pf to 200pf, I got some errors relating to diagonals at Jacobian point, stopping the spectre to simulate further.
Can you please let me know what should I do in order to eliminate the error?

Moreover, when the input voltage is in the order of few mV like 75mV Pk-Pk, rectified output is almost Nill and when I slowly increase the vol, the output voltage is slowly rising but I find ripples.
Once the input voltage crosses 1V, then I find some mV of rectified output voltage.

This design of this rectifier is used for RFID applications.
Can you please let me know how to proceed further.

Hi,

Please someone tell me how to proceed further.


Thanks