Editing Pulse-width modulation (section)

===PWM sampling theorem===
The process of PWM conversion is non-linear and it is generally supposed that low pass filter signal recovery is imperfect for PWM. The PWM sampling theorem<ref>J. Huang, K. Padmanabhan, and O. M. Collins, “The sampling theorem with constant amplitude variable width pulses”, IEEE transactions on Circuits and Systems, vol. 58, pp. 1178 - 1190, June 2011.</ref> shows that PWM conversion can be perfect:

<blockquote>Any [[bandlimited]] [[baseband]] signal whose amplitude is within ±0.637 can be represented by a PWM waveform of unit amplitude (±1). The number of pulses in the waveform is equal to the number of [[Nyquist rate|Nyquist samples]] and the peak constraint is independent of whether the waveform is two-level or three-level.</blockquote>

For comparison, the [[Nyquist–Shannon sampling theorem]] can be summarized as:

<blockquote>If you have a signal that is bandlimited to a bandwidth of f<sub>0</sub> then you can collect all the information there is in that signal by sampling it at discrete times, as long as your sample rate is greater than 2f<sub>0</sub>.<ref>{{cite web |last=Wescott |first=Tim |date=August 14, 2018 |title=Sampling: What Nyquist Didn't Say, and What to Do About It |url=http://www.wescottdesign.com/articles/Sampling/sampling.pdf |publisher=Wescott Design Services |quote=The Nyquist-Shannon sampling theorem is useful, but often misused when engineers establish sampling rates or design anti-aliasing filters.}}</ref></blockquote>