This application relates to modulators for providing time-encoded signals and in particular PWM signals. A modulator (200) has a first controlled oscillator (201P) configured to receive a first oscillator driving signal and output a first oscillation signal (S1). An accumulator (204) is configured to provide an accumulator value (VAL) based on a number of pulses of the first oscillation signal and a hysteretic comparator (205) alternates between first and second output states based on a hysteretic comparison of the accumulator value with a defined reference (REF). The first oscillator driving signal is based on a combination of an input signal and a feedback signal derived from an output of the hysteretic comparator. A second controlled oscillator (201N) may be configured to receive a second oscillator driving signal and output a second oscillation signal (S2) and the accumulator may provide the accumulator value based on a difference in the number of pulses of the first oscillation signal and the second oscillation signal.