Patent ID: 7902922

Claim:
A feedforward amplifier, comprising: a divider configured to distribute an input signal into a main amplifier path and a linear transfer path, the main amplifier path including a main amplifier which is a harmonic reaction amplifier; a combiner/divider configured to combine an output signal of the main amplifier path and an output signal of the liner transfer path to generate a signal input to a main amplifier output transfer path and a signal input to a distortion injection path including an auxiliary amplifier; and a power combiner configured to combine an output signal of the main amplifier output transfer path and an output signal of the distortion injection path and thereby outputting an output signal; a first directional coupler configured to extract a part of the output signal of the power combiner; a detector configured to detect, from the signal extracted by the first directional coupler, a main wave component which is the input signal input in the feedforward amplifier and upper and lower out-of-band distortion components generated by the main amplifier; a power measuring part configured to measure an output power of the feedforward amplifier and supply power to the feedforward amplifier; and a controller configured to control an operating point of the harmonic reaction amplifier to maximize power efficiency calculated from the output power and the supply power under a condition that an adjacent channel leakage power ratio calculated from the detected main wave component and the detected upper and lower out-of-band distortion components are lower than or equal to a predetermined reference value.