Created by
Created February 24, 2012
Last modified February 24, 2012
Tags filter   low-pass   pwm  


A simple example of a low pass filter on a digital PWM output.


The output of a PWM signal passed through a simple RC low pass filter. This situation is common in simple audio projects where you have a digital source generating a PWM audio signal and you want to filter the PWM signal back into the analog waveform.

Things to explore in CircuitLab

  • Run the Transient Analysis and observe the PWM signal tracking compared to the analog input waveform.

  • Observe the output waveform. In what ways is the input waveform distorted at the output? Can you tweak the RC filter to get rid of more of the ripple? What are the trade-offs that happen when you remove more of the ripple with this type of filter?


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