In an analog-to-frequency converting circuit, a set of switches receive a first sense signal indicative of a current and provides a second sense signal that alternates between an original version of the first sense signal and a reversed version of the first sense signal, under control of a switching signal. An integral comparing circuit integrates the second sense signal to generate an integral value and generates a train of trigger signals. Each trigger signal is generated when the integral value reaches a preset reference. A compensation circuit compensates for the integral value with a predetermined value in response to each trigger signal. A control circuit generates the switching signal such that a time interval during which the second sense signal is the original version and a time interval during which the second sense signal is the reversed version are substantially the same.