sine-wave to square-wave

[perado]

I want to transform an input low power sine-wave to a square-wave suitable for switching a transistor, I want to know all circuit topologies that can do it and which one is the best?

 

[andre_luis]

You can use push pull, controlling gate timming in order to filter all than first odd harmonics.



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[perado]

why filter!? I want to transform sine to square not square to sine

 

[pedja089]

You can use a simple comparator...

 

[kabiru]

You can rectified the sinewave signal and pass it through a schmit triger or use a simple comparator.

 

[enjunear]

A comparator would be your simplest approach, but finding one with enough output capability to drive a transistor might require additional circuits, depending on the output configuration of your comparator. Using an op-amp with super-high gain and a little hysteresis might do the trick: a rail-to-rail swing to create the square wave, and a little deadband near zero-crossing to keep the crossover point clean from noise).

An op-amp buffer amplifier may also be useful, depending on how hard/fast you need to drive the transistor. Additionally, you could go with a Darlington pair for the transistor, or double-up your transistor count and make your own pseudo-Darlington arrangement to boost the current driving the output transistor.