An adjustable time duration to drive the PWM (Pulse-Width Modulation) output to reduce thermal noise

摘要

The noise introduced into the output signal of the pulse-width modulator (PWM) can be reduced by changing the time duration during which the switch drives the output node. Since the power supplies coupled to the switches are the source of the noise in the output signal of the PWM, the time duration for which the power supplies drive the output can be reduced to obtain a subsequent reduction of the noise in the output signal. For example, when a small signal is desired to be output by PWM, the switches can operate for a shorter time duration. Thus, the switches couple the noise sources to ground for the duration of the cycle to reduce the contribution of noise to the output. However, when a larger signal is desired to be output by the PWM, the switches may operate for a longer time duration or the conventional time duration described above.