A signal conversion circuit includes a first pair of capacitors and a comparator. The first pair of capacitors includes a first capacitor and a second capacitor having a same capacitance value. Each of the first capacitor and the second capacitor is coupled to an input signal during a first sampling phase, while uncoupled from the input signal during a first conversion phase after the first sampling phase. The comparator has a first input terminal and a second input terminal. During the first conversion phase, the first capacitor is coupled between the first input terminal and a first reference signal, the second capacitor is coupled between the first input terminal and a second reference signal different from the first reference signal, and the comparator is configured to compare a signal level at the first input terminal and a signal level at the second input terminal to convert the input signal.