Help comparator circuit for this PWM signal inverter
The 741 won't do what you are trying to do, at least not if you are using it with a single supply voltage.

The 741 cannot handle input signals that go within about 2 volts of the supply rails.  So, for a single voltage supply that would be input from about 2V to about Supplyvoltage - 2V.

Since your input signals go to zero volts, you won't get what you expect at the output.

The 741 also cannot drive its output to the voltage rails, within about the same range - so, output from 2V to about supplyvoltage -2V.

Any modern rail-to-rail op amp made for single supply operation, and which has enough bandwidth, would be better than the 741.



Aside from the obvious limitations of the 741, there's not much else that anyone can tell you since you haven't posted a schematic.