thank you so much Mr. keith, i realy appreciate your help.
Actually i have designed a receiver circuit in which i'm using a pin photodiode, preamplifier, comparator, positive edge D-flipflop, transister and capacitor. i have applied "current mode time to amplitude converter" method.
now my problem is how to charge the capacitor to get 5V across it in 80ns? and hold that value until read by ADC of microcontroller.
i mean what value of capacitor and the constant current should i use that will charge the capacitor?
and secondly can i generate 80ns pulse at 1kHz PRF with pic 16F877?