Pulse Width Modulation ADC - Version 2.0

This circuit uses a comparator (or an op amp in this circuit) to compare an analog input voltage on the non inverting input to a triangle or sawtooth waveform on the inverting input. This generates a PWM signal whose positive duty cycle corresponds to the analog value of the input signal. In order to convert this pwm signal to a digital one, you simply AND a counter clock signal, and a start/stop square wave to start and stop the counting. The output pulses are then sent on to a counter IC to convert to a binary value corresponding to the analog input voltage. The binary value is the last value output by the counters before being reset by the mosfet pulse circuit. This is a very slow circuit to watch, but try playing around with the wiper position of the potentiometer to change the analog input voltage and see how the circuit performs. As you can probably tell just by looking at it and watching it perform, I wouldn't say this is actually a practical ADC type, just fun to play around with Fixed the simulation time issue somewhat, now you shouldn't have to wait an hour to see how each cycle works!

published 6 years ago