Feedforward amplifier

A feedforward amplifier for compensating for distortion produced in an amplifier, comprising:

• a distortion detection loop for detecting the distortion, the distortion detection loop having an amplification route;
• a distortion compensation loop for compensating for the distortion, the distortion compensation loop having a distortion amplification route;
• a first variable phase shifter for varying phase of a signal;
• a second variable phase shifter for varying the phase of the signal passed through the first variable phase shifter;
• and
• a phase control portion for controlling an amount of variation in phase in the first variable phase shifter and, the phase control portion, when values of the amount of variation in phase are concentrated toward either ones of relatively-larger directions and relatively-smaller directions, for controlling an amount of variation in phase in the second variable phase shifter according to whether the concentrated directions,
• wherein the first variable phase shifter, the second variable phase shifter and the phase control portion are provided on at least one of the amplification route and the distortion amplification route.