PWM Drive Simulation
I'm sorry, but I'm going to sound harsh.

It's not a matter of what you're doing wrong - I can't figure out what you're doing right.

Why are you feeding logic gates with a sine wave? You should be using a square wave with a low of 0 and a high of 5 volts. What technology are the gates? CMOS? TTL? What is the logic supply voltage?

Why do you have resistors in this circuit? What function are they supposed to serve?

Why do you expect the gate outputs to change? It looks as if the sine wave has too low an amplitude to cause the gates to change state, so you would expect the NOR output to stay high (both inputs are low), and the AND output to stay low (same reason). And that's exactly what's happening.

If the upper trace is the NOR gate output, it is not pulsing, although its amplitude is varying somewhat.

So I'm stumped. Please explain exactly why you think the circuit should work, and exactly what the circuit is supposed to do.