An apparatus, comprising: an output node; a first source for driving the output node in a positive direction; a first switch coupled to the first source and to the output node, wherein the first switch is configured such that when connected in a first phase drives the output node in a positive direction and contributes noise and when connected in a second phase does not contribute to output noise or drive the output node in any direction; a second source for driving the output node in a negative direction; a second switch coupled to the second source and to the output node, wherein the second switch is configured such that when connected in a third phase drives the output node in a negative direction and contributes noise and when connected in a fourth phase does not contribute to output noise or drive the output node in any direction; and a controller coupled to the first switch and coupled to the second switch and configured to perform steps comprising: receiving a reference signal; operating the first switch and the second switch to generate a pulse width modulation representation of the reference signal at the output node; and adjusting a time duration that the first switch and the second switch are coupled to the output node based on an envelope level of an output signal at the output node, wherein adjusting comprises: in a first mode for a first range of the envelope level, coupling the first switch and the second switch to the output node for a first duration of time; in a second mode for a second, lower range of the envelope level, coupling the first switch and the second switch to the output node for a second duration of time shorter than the first duration of time; and switching between the first mode and the second mode based, at least in part, on the envelope level. an output node; a first source for driving the output node in a positive direction; a first switch coupled to the first source and to the output node, wherein the first switch is configured such that when connected in a first phase drives the output node in a positive direction and contributes noise and when connected in a second phase does not contribute to output noise or drive the output node in any direction; a second source for driving the output node in a negative direction; a second switch coupled to the second source and to the output node, wherein the second switch is configured such that when connected in a third phase drives the output node in a negative direction and contributes noise and when connected in a fourth phase does not contribute to output noise or drive the output node in any direction; and a controller coupled to the first switch and coupled to the second switch and configured to perform steps comprising: receiving a reference signal; operating the first switch and the second switch to generate a pulse width modulation representation of the reference signal at the output node; and adjusting a time duration that the first switch and the second switch are coupled to the output node based on an envelope level of an output signal at the output node, wherein adjusting comprises: in a first mode for a first range of the envelope level, coupling the first switch and the second switch to the output node for a first duration of time; in a second mode for a second, lower range of the envelope level, coupling the first switch and the second switch to the output node for a second duration of time shorter than the first duration of time; and switching between the first mode and the second mode based, at least in part, on the envelope level. receiving a reference signal; operating the first switch and the second switch to generate a pulse width modulation representation of the reference signal at the output node; and adjusting a time duration that the first switch and the second switch are coupled to the output node based on an envelope level of an output signal at the output node, wherein adjusting comprises: in a first mode for a first range of the envelope level, coupling the first switch and the second switch to the output node for a first duration of time; in a second mode for a second, lower range of the envelope level, coupling the first switch and the second switch to the output node for a second duration of time shorter than the first duration of time; and switching between the first mode and the second mode based, at least in part, on the envelope level. in a first mode for a first range of the envelope level, coupling the first switch and the second switch to the output node for a first duration of time; in a second mode for a second, lower range of the envelope level, coupling the first switch and the second switch to the output node for a second duration of time shorter than the first duration of time; and switching between the first mode and the second mode based, at least in part, on the envelope level.