Editing Pulse-width modulation (section)

=== Asynchronous delta-sigma PWM ===
{{Main|Delta-sigma modulation#Asynchronous delta-sigma modulation}}

[[File:Sigma-delta_PWM.svg|frameless|400x400px]]

[[Asynchronous circuit|Asynchronous]] (i.e. unclocked) delta-sigma modulation produces a PWM output (blue in bottom plot) which is subtracted from the input signal (green in top plot) to form an error signal (blue in top plot). This error is integrated (magenta in middle plot). When the integral of the error exceeds the limits (the upper and lower grey lines in middle plot), the PWM output changes state. By integrating the difference of the error with the input signal, delta-sigma modulation [[Noise shaping|shapes noise]] of the resulting spectrum to be more in higher frequencies above the input signal's band.