Suppose you want to look at a square wave signal riding on top of a large DC bias. This seems like it should be simple, but I was thinking about this today and I don't know how to do it.(adsbygoogle = window.adsbygoogle || []).push({});

Normally, one would remove a DC offset with a high-pass filter (or just a capacitor). However, with a square wave, the signal itself is DC, so this kind of solution would just result in a series of approximate delta pulses. I suppose this gives you some timing information, but what if you need to know the integral of the signal?

The only solution that occurs to me seems overly complicated and assumes you have access to the constant bias voltage: pass the bias voltage through a unity gain inverting amplifier then add the signal and the bias using a summing amplifier. Does this sound reasonable? I suppose it's not too complicated, but I feel like this should be doable without op-amps. And what if you don't have access to the bias voltage?

This isn't actually an issue for me at the moment, I'm just curious how this would be handled by more capable electronics guys. I'm pretty sure you can look at a square wave on a AC coupled oscilloscope (or did I dream this up?), so I think it should be possible.

Thanks, Rob

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# Removing a DC Offset from a Square Wave Signal

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