Patent ID: 9577586
Date: 2017-02-21
CPC Classifications: H03F

Claim:
1. A feed reflected Doherty amplifier comprising; at least one input power splitter which divides the input signal to produce a first split signal and a second split signal, at least one carrier amplifier amplifying the first split signal to generate the carrier output signal and having a reflection coefficient at its output which remains constant below a threshold point and decreases depending on the load current driven by the peaking amplifier above the said threshold point, at least one impedance inverting network coupled to the output of the carrier amplifier, at least one output directional coupler coupled at the output path of the carrier amplifier to have a reflected coupled output signal of the carrier amplifier at its isolated port, which increases in accordance with the increasing carrier amplifier output signal below the said threshold point and decreases with the decreasing output reflection coefficient of the carrier amplifier above the said threshold point, at least one phase shift element connected to the isolated port of the output coupler to adjust the phase of the said reflected coupled output signal, at least one input directional coupler coupled between the input power splitter and the input path of the peak amplifier, and its isolated port is connected to the phase shift element to combine the said second split signal of the input power splitter and the said reflected coupled output signal of the carrier amplifier to drive the peaking amplifier with a dynamically controlled signal which remains in a substantially lowered amplitude below the said threshold point and increases with the decreasing output reflection coefficient of the carrier amplifier above the said threshold point, at least one peaking amplifier operating in class B which amplifies the combined signal at the output of the input directional coupler to generate a peaking output signal, at least one load.