US 5,493,252 A · Feedforward distortion compensation circuit

Abstract

A feedforward distortion compensation circuit includes a main amplification path, an auxiliary amplification path, first and second transmission paths, a signal attenuation path, a first signal injector, a first signal distributor, a second signal injector, a first signal synthesizer, a first phase difference detector, a first level detector, a second phase difference detector, a second signal synthesizer, a second level detector, and a control circuit. The control circuit controls a first variable attenuator and a first variable phase shifter such that a detection level of the first level detector becomes minimum, and first pilot signals synthesized by the first signal synthesizer on the basis of a phase difference detected by the first phase difference detector respectively have opposite phases, and controls a second variable attenuator and a second variable phase shifter such that a detection level of the second level detector becomes minimum, and second pilot signals synthesized by the second signal synthesizer on the basis of a phase difference detected by the second phase difference detector respectively have opposite phases.

A feedforward distortion compensation circuit comprising:

a main amplification path including main amplifying means for amplifying a signal, first variable attenuating means for adjusting an attenuation amount, and first variable phase shifting means for adjusting a phase shift amount;
an auxiliary amplification path including auxiliary amplifying means for amplifying a signal, second variable attenuating means for adjusting an attenuation amount, and second variable phase shifting means for adjusting a phase shift amount;
first and second transmission paths for transmitting signals;
a signal attenuation path for attenuating a signal by predetermined attenuation;
first signal injecting means for injecting a first pilot signal having a specific frequency into an input signal from an input terminal;
first signal distributing means for distributing the input signal, into which the first pilot signal is injected, to said main amplification path and said first transmission path;
second signal injecting means for injecting a second pilot signal having a specific frequency into said main amplification path;
second signal distributing means for distributing an output signal from said main amplification path to said second transmission path and said signal attenuation path;
first signal synthesizing means for synthesizing an output signal from said first transmission path with an output signal from said signal attenuation path to output a synthesized signal to said auxiliary amplification path;
first phase difference detecting means for detecting a phase difference between the first pilot signal passing through said main amplification path and the first pilot signal passing through said first transmission path;
first level detecting means for detecting a level of the first pilot signal passing through said auxiliary amplification path;
second phase difference detecting means for detecting a phase difference between the second pilot signal passing through said auxiliary amplification path and the second pilot signal passing through said second transmission path;
second signal synthesizing means for synthesizing an output signal from said auxiliary amplification path with an output signal from said second transmission path to output a synthesized signal to an output terminal;
second level detecting means for detecting a level of the second pilot signal included in an output signal from said second signal synthesizing means;
and
control means for controlling said first variable attenuating means and said first variable phase shifting means such that a detection level of said first level detecting means becomes minimum, and the first pilot signals synthesized by said first signal synthesizing means on the basis of the phase difference detected by the first phase difference detecting means respectively have opposite phases, and controlling said second variable attenuating means and said second variable phase shifting means such that a detection level of said second level detecting means becomes minimum, and the second pilot signals synthesized by said second signal synthesizing means on the basis of the phase difference detected by said second phase difference detecting means respectively have opposite phases.

13 more elements

Feedforward distortion compensation circuit

Life of this patent

Feedforward distortion compensation circuit

Life of this patent

Abstract

Claims19