use an op-amp. your input signal goes to the inverting input. the signal to the non inverting input would be a triangular wave from an oscillator circuit, where its peak to peak value should be greater than the signal in the inverting. There are lot of text books that discuss this kind of comparator, unfortunately i dont know much of the titles of these books.
Thank you. But I don't know how to design the chopper comparator and what the chopper comparator is.What is the meaning of "chopper" in the chopper comparator?
Chopper stabilization (CHS) is a modulation technique that can be employed to reduce the effects of op-amp imperfections including noise (mainly 1/f and thermal noise) and the input-referred dc offset voltage. Ideally, a chopper stabilized amplifier can eliminate dc offset and low-frequency (primarily 1/f) noise.