Cascode CMOS RF power amplifier with programmable feedback cascode bias under multiple supply voltages

A Radio Frequency (RF) power amplifier operable with differing battery supply voltages, the RF power amplifier comprising:

• a transconductance stage having a transconductance device with an RF signal input;
• a cascode stage having at least one cascode transistor, the cascode stage coupled in series with the transconductance stage between a battery voltage node and ground, the cascode stage having an RF signal output and at least one bias input to the at least one cascode transistor;
• and
• cascode bias feedback circuitry operable to:
• apply fixed bias voltage(s) to the at least one bias input for a low battery voltage;
• and
• apply feedback bias voltage(s) to the at least one bias input for a high battery voltage, the feedback bias voltage(s) based upon a voltage of the battery voltage node.

A method for operating of a Radio Frequency (RF) cascode power amplifier supplied by differing battery supply voltage levels comprising:

• determining a battery supply voltage;
• comparing the battery supply voltage to at least one voltage threshold;
• for a first comparison result to indicate a relatively lower battery voltage, applying fixed bias voltage(s) to at least one bias input of a cascode stage of the RF cascode power amplifier;
• and
• for a second comparison result to indicate a relatively higher battery voltage, applying feedback bias voltage(s) to the at least one bias input of the RF cascode power amplifier, wherein the feedback bias voltage(s) is based upon an output voltage of the RF cascode power amplifier.