Patent ID: 9407216
Filing Date: 2016-08-02
CPC Classification: H03F,H03G

Claim Text:
1. An analog feedback amplifier including: a variable phase shifter that adjusts a phase of an input signal; a variable gain amplifier that amplifies the input signal; and a power amplifier that amplifies the input signal, wherein the variable phase shifter, the variable gain amplifier and the power amplifier are connected in series in this order, or the variable gain amplifier, the variable phase shifter and the power amplifier are connected in series in this order, the analog feedback amplifier comprising: a first amplitude adjusting circuit that adjusts amplitude of the signal after the amplification by the power amplifier; a second amplitude adjusting circuit that adjusts amplitude of the signal after the amplification by the variable gain amplifier; a first delay circuit that delays the signal after the amplitude adjustment by the second amplitude adjusting circuit; a first signal difference detecting circuit that detects difference between the signal after the amplitude adjustment by the first amplitude adjusting circuit and the signal delayed through the first delay circuit, and outputs the difference as a first feedback signal; a second signal difference detecting circuit that detects the difference between the input signal and the first feedback signal output from the first signal difference detecting circuit; a gain control circuit that detects difference between the difference detected by the second signal difference detecting circuit and a second feedback signal, and controls gain of the variable gain amplifier in accordance with the difference; and a third amplitude adjusting circuit that adjusts amplitude of the difference detected by the gain control circuit, adds the difference after the amplitude adjustment to the input signal, and supplies the addition result to the gain control circuit as the second feedback signal.