1. An envelope tracking supply modulator comprising: an amplifier comprising an output, an inverting input, and a non-inverting input; a first node at the inverting input, wherein the first node is coupled to a feedback path from the output; a second node at the non-inverting input, wherein the second node is coupled to an inverting amplifier or buffer coupled to the first node, and wherein the second node is coupled to a reference voltage source; and a transconductance amplifier coupled to the first node, wherein the transconductance amplifier is configured to receive an input representing the envelope waveform of a signal.