#hardware design to filter out PWM ripple by inverting it and AC-coupling the inverted ripple into your low-pass filter; also they’re using a summing junction to get 14.5 ENOB or so out of a couple of 8-bit DACs (again, PWM). Article does have a typo where it says ’HC14 when it means ’HC04. By Stephen Woodward.
#hardware design of the DAC that filters out PWM ripple by inverting it