RF amplifier

A method comprising:

• providing a first supply voltage to a first amplifier comprising a first transistor having a first device periphery;
• providing a second supply voltage to a second amplifier comprising a second transistor having a second device periphery smaller than the first device periphery, wherein the second supply voltage is higher than the first supply voltage;
• providing an RF input signal to inputs of the first amplifier and the second amplifier;
• amplifying the RF input signal using the first amplifier and the second amplifier;
• and
• combining an output of the first amplifier with an output of the second amplifier using a combining network to form an RF output signal, wherein
• the first device periphery, the first supply voltage, the second device periphery, and the second supply voltage are configured to maintain a junction temperature ratio of between 0.3 and 1.0, and
• the junction temperature ratio is a ratio of a temperature of the first amplifier to a temperature of the second amplifier.

An amplifier comprising:

• a first gallium nitride (GaN) transistor coupled to a first supply node configured to receive a first supply voltage and having a first device periphery;
• a second GaN transistor coupled to a second supply node configured to receive a second supply voltage higher than the first supply voltage and having a second device periphery smaller than the first device periphery, wherein the second GaN transistor is biased as a class C amplifier;
• an input network coupled to an input port, a control node of the first GaN transistor, and a control node of the second GaN transistor;
• and
• a combining network coupled to an output port, an output node of the first GaN transistor, and an output node of the second GaN transistor, wherein
• the first device periphery, the first supply voltage, the second device periphery, and the second supply voltage are configured to maintain a junction temperature ratio of between 0.3 and 1.0 for an RF input signal having a given peak-to-average ratio, and
• the junction temperature ratio is a ratio of a temperature of the first GaN transistor to a temperature of the second GaN transistor.