Phase shift and attenuation circuits for use with multiple-path amplifiers

A Doherty power amplifier comprising:

• a radio frequency (RF) input;
• first and second parallel amplifier paths selected from a main amplifier path and a peaking amplifier path;
• a divider circuit configured to power divide a first RF signal received at the RF input into second and third RF signals, wherein the divider circuit is further configured to produce the second and third RF signals with a ninety degree phase shift between the second and third RF signals;
• a first signal adjustment circuit coupled to the divider circuit, wherein the first signal adjustment circuit comprises a first adjustable phase shifter circuit that receives the second RF signal from the divider circuit and applies a first phase shift to the second RF signal to produce a fourth RF signal at a first power output that is coupled to the first amplifier path;
• a second signal adjustment circuit coupled to the divider circuit in parallel with the first signal adjustment circuit, wherein the second signal adjustment circuit comprises a first variable attenuator circuit that receives the third RF signal from the divider circuit and applies a first attenuation to the third RF signal to produce a fifth RF signal at a second power output that is coupled to the second amplifier path;
• and
• a data interface, wherein the Doherty power amplifier is configured to receive data indicating the first phase shift and the first attenuation through the data interface, and the Doherty power amplifier is further configured to control, based on the data, application of the first phase shift by the first signal adjustment circuit, and application of the first attenuation by the second signal adjustment circuit.