Power supply control system

A circuit for biasing a power amplifier (PA), the circuit comprising:

• a DC power supply, wherein the DC power supply provides two or more DC voltage levels;
• a DC switch system for switchably routing one of the two or more DC voltage levels at a time to an output voltage supply node, wherein the DC switch system comprises:
• a switch circuit for each of the two or more DC voltage levels, the switch circuit for each DC voltage level comprising:
• a compound switch circuit comprising:
• a first field effect transistor (FET), wherein a drain of the first FET is connected to a respective DC voltage level;
• and
• a second FET, wherein a source of the second FET is connected to a source of the first FET, wherein a drain of the second FET is connected to the output voltage supply node, wherein a gate of the first FET and a gate of the second FET are connected together to form a first shared source node;
• voltage driving circuitry to drive an “on” gate-to-source voltage level of the compound switch above a turn-on gate-to-source voltage of the first and second FETs when the compound switch is to be placed in an “on” state;
• and
• a bootstrap capacitor, configured to be pre-charged to a bootstrap charging power supply voltage when the compound switch is in an “off” state, and configured to provide the bootstrap charging power supply voltage as the “on” gate-to-source voltage level to the voltage driving circuitry when the compound switch is to be placed in the “on” state.