I have a sine wave of 100 mV and 50 Hz. I want to design a circuit that converts this sine wave into a square wave as shown in a figure.

Enter image description here

  • \$\begingroup\$ You would almost certainly want to add hysteresis to your solution for a low level low frequency application \$\endgroup\$
    – sstobbe
    Apr 12, 2019 at 15:04
  • \$\begingroup\$ Does the OP want a 50% duty cycle? in which case, some zero-crossing is needed. \$\endgroup\$ Apr 12, 2019 at 21:23

1 Answer 1


The easiest way to do this would be to use a comparator.

enter image description here

Picture taken from linked site

All you have to do is set your Vref level to where you want your square wave to trigger. When the sine wave crosses the Vref level, the comparator output will go high. As it approaches it again and goes below the Vref level, the comparator output goes low.

You will then get yourself a square wave.

Be aware the example shown in the graphic is of a non-inverting comparator. An inverting comparator works with the same principle, but the output is inverted

  • \$\begingroup\$ The OP seems to want to cut off the negative half of the sine wave, so a diode may be needed at the input. \$\endgroup\$
    – JimmyB
    Apr 12, 2019 at 15:01
  • 3
    \$\begingroup\$ @JimmyB Not if you pick a comparator that can handle a negative input voltage. \$\endgroup\$
    – Hearth
    Apr 12, 2019 at 15:03
  • \$\begingroup\$ A diode for 100mV will be hard to find... \$\endgroup\$
    – Eugene Sh.
    Apr 12, 2019 at 15:08

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