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Removing DC from square wave signal

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raed_microwave

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Hi,

Which circuit can remove dc component from a square wave signal? I know that the capacitor is remove the dc but only for sine wave signal.
I hope that u can help me

regards
 

A capacitor will remove DC from a square wave as well, but only if the CR time constant of the capacitor and load resistor is large compared to the period of the square wave, otherwise you will get droop in the flat portion of the square wave.

Keith
 

raed_microwave said:
Hi,

Which circuit can remove dc component from a square wave signal? I know that the capacitor is remove the dc but only for sine wave signal.
I hope that u can help me

regards
Click to expand...

Why not using a differential amplifier (subtractor) - preferrably made with opamps?
 

What about an (RR) Instr.Amp_if offset is changing?
K.
 

keith1200rs said:
That would work if the DC voltage offset is fixed.
Keith
Click to expand...

Yes, that's evident.
However, (nearly) everything is possible. You could measure/detect the mean value and correspondingly control the subtractor in a closed loop.
 

thanks for all suggestions but all of them I can not use it because I can't measure the mean of the signal and the square wave is already generated from square law detector and the input signal of detector is RF signal modulated with square wave carrier signal. The output of detector is just the envelop with dc component...So I want to remove this dc component.
 

You didn't manage to aks a clear question. There are many ways to set the DC level of a demodulated signal, and they would be usually choosen according to signal processing requirements. High pass filtering e.g. would result in a bipolar output signal, actually removing the DC component. But your intentions are possibly different? There are non-linear and time discrete DC restoring methods as alternatives.
 

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