Circuit Operation In this design, multipliers U3 and U4 both act as integrators with C14 integrating the output of U3 and C11 integrating U4’s output ( Fig. 1 ).

All four circuit variants relyon the same principle: using the analogswitch to adjust the duty-cycle ratiobetween two analog input levels, and alowpass filter (LPF) to eliminate thePWM chopping ...