A sinusoidal-amplitude-to-digital-output circuit includes a comparator with an input terminal, a reference terminal and an output terminal. A digital bus is connected to the output terminal. A reference voltage source is connected to the reference terminal. A feedback resistor is connected in parallel with the comparator between the output terminal and the input terminal to provide hysteresis for noise rejection such that circuit converts voltage received at the input terminal into a digital pulse-width modulated waveform that varies non-linearly with amplitude of the voltage received at the input terminal.