Skyworks Solutions, Inc.
Programmable low dropout regulators with fast transient response when programming output voltage

Abstract:

Apparatus and methods for programmable low dropout regulators for radio frequency (RF) electronics are provided herein. In certain configurations, a power amplifier system includes a multi-stage power amplifier that amplifies a radio frequency signal and includes a driver stage and an output stage. The power amplifier system further includes an envelope tracker that controls a supply voltage of the output stage in relation to an envelope of the radio frequency signal, and a programmable low dropout regulator that includes an output that provides a programmable supply voltage to the driver stage. The programmable low dropout regulator includes an output capacitor electrically connected to the output, a regulation transistor having a drain electrically connected to the output, and an alternative discharge circuit that discharges the output capacitor in response to programming the programmable supply voltage from a high voltage level to a low voltage level.