Multiple-mode RF power amplifiers

A multiple-mode radio frequency (RF) power amplifier comprising:

• first and second amplifier system inputs;
• an amplifier system output;
• a first amplifier coupled to the first amplifier system input, wherein the first amplifier is configured to receive a first input RF signal from the first amplifier system input and to produce a first amplified RF signal at an output of the first amplifier;
• a second amplifier coupled to the second amplifier system input, wherein the second amplifier is configured to receive a second input RF signal from the second amplifier system input and to produce a second amplified RF signal at an output of the second amplifier;
• combiner circuitry having first, second, third, and fourth combiner ports, wherein the first combiner port is coupled to the output of the first amplifier, the second combiner port is coupled to the output of the second amplifier, the third combiner port is coupled to the amplifier system output, and the combiner circuitry is configured to combine the first and second amplified RF signals to produce a combined amplified RF signal at the third combiner port;
• a switchable impedance circuit with an input terminal coupled to the fourth combiner port, wherein
• when the switchable impedance circuit is in a first state, the fourth combiner port is coupled through the switchable impedance circuit to a terminating system impedance to configure the multiple-mode RF power amplifier as a balanced amplifier,
• when the switchable impedance circuit is in a second state, the fourth combiner port is coupled through the switchable impedance circuit to an open circuit impedance to configure the multiple-mode RF power amplifier as a first type of Doherty power amplifier, and
• when the switchable impedance circuit is in a third state, the fourth combiner port is coupled through the switchable impedance circuit to a short circuit impedance to configure the multiple-mode RF power amplifier as a second type of Doherty power amplifier;
• and
• a bias controller configured to provide a first gate bias voltage to the first amplifier, and to provide a second gate bias voltage to the second amplifier, wherein,
• when the switchable impedance circuit is in the first state, the bias controller provides the first and second gate bias voltages to configure the first amplifier to operate in a class AB operational mode, and to configure the second amplifier in the class AB operational mode,
• when the switchable impedance circuit is in the second state, the bias controller provides the first and second gate bias voltages to configure the first amplifier to operate in the class AB operational mode, and to configure the second amplifier in a class C operational mode,
• when the switchable impedance circuit is in the third state, the bias controller provides the first and second gate bias voltages to configure the first amplifier to operate in the class C operational mode, and to configure the second amplifier in the class AB operational mode, and
• wherein the bias controller is further configured to provide a first drain bias voltage to the first amplifier, and to provide a second drain bias voltage to the second amplifier, wherein,
• when the multiple-mode RF power amplifier is configured as a balanced amplifier, the bias controller provides a nominal drain bias voltage to the first and second amplifiers,
• when the multiple-mode RF power amplifier is configured as either the first or second type of Doherty power amplifier, the bias controller provides a scaled up drain bias voltage to whichever of the first or second amplifier is configured to operate in the class AB operational mode, and the bias controller provides a scaled down drain bias voltage to whichever of the first or second amplifier is configured to operate in the class C operational mode.