Square wave-to-sine wave converter

A circuit, comprising:

• a bandpass filter having a bandpass input coupled to a square wave input and a bandpass output configured to provide a sine wave signal, the bandpass filter including a first binary-weighted programmable resistor array;
• and
• a self-tracking circuit including:
• a comparator having a first input coupled to the bandpass output, a second input coupled to a reference signal, and a comparator output;
• a phase detector including:
• a first data flip-flop having a first clock input, a first data input coupled to the comparator output, and a first data output;
• a second data flip-flop having a second clock input, a second data input coupled to the comparator output, and a second data output;
• a first time delay element having an input coupled to the square wave input, and having an output coupled to the first clock input;
• and
• a second time delay element having an input coupled to the square wave input, and having an output coupled to the second clock input;
• wherein the phase detector detects whether a phase of the comparator output leads or lags a phase of the input square wave, and produces a control signal of a first state responsive to the phase of the comparator output leading the phase of the input square wave, and produces the control signal of a second state responsive to the phase of the comparator output lagging the phase of the input square wave.