This disclosure provides systems, apparatus, and methods for switching a portion of a power amplifier on and off during different modes of operation. In one aspect, a control circuit can include separate switches to provide bias currents to different portions of a power amplifier. The control circuit can include another switch to electrically connect outputs of the separate switches in a first mode of operation (for example, a high power mode) and electrically isolate the outputs of the separate switches in a second mode of operation (for example, a low power mode). In some implementations, a circuit element, such as a field effect transistor or a diode, can turn off one of the separate switches in the second mode. Alternatively or additionally, another circuit element, such as a field effect transistor or a diode, can prevent a power amplifier portion from turning on in the second mode.