Feedforward amplifier with reduced distortion in wide band

Claim 2

A feedforward amplifier, comprising: a main amplifier circuit including: a first equalizing means for adjusting frequency characteristics of both amplitude and phase of an input signal to provide a first adjusted signal; and a first amplifying means for amplifying the first adjusted signal to provide a first amplified signal; the first equalizing means and the first amplifying means being arranged in a cascade connection so that the output of the main amplifier circuit is the first amplified signal; a first delay line for delaying the input signal to provide a first delayed signal; a second delay line for delaying the first amplified signal to provide a second delayed signal; an auxiliary amplifier circuit including: a distortion sensing means for synthesizing a branched signal of the first amplified signal with the first delayed signal to provide a distortion signal representative of a distortion of the first amplified signal; a second equalizing means for adjusting frequency characteristics of both amplitude and phase of the distortion signal to provide a second adjusted signal; and a second amplifying means for amplifying the second adjusted signal to provide a second amplified signal; the distortion sensing means, the second equalizing means and the second amplifying means being arranged in a cascade connection so that the output of the auxiliary amplifier circuit is the second amplified signal; and a distortion removing means for synthesizing the second amplified signal with the second delayed signal to remove said distortion from the second delayed signal.

Claim 3

A feedforward amplifier, comprising: oscillator means for generating an oscillation signal with a controllable frequency; first coupling means for superimposing the oscillation signal on an input signal to provide a superimposed signal; distributor means for distributing the superimposed signal as a first distributed signal and a second distributed signal; equalizing means for adjusting frequency characteristics of both amplitude and phase of the first distributed signal to provide an adjusted signal; amplifying means for amplifying the adjusted signal to provide an amplified signal; second coupling means for coupling the second distributed signal with a phase-reversed signal of the amplified signal to provide a coupled signal; detecting means for detecting the oscillation signal, as it is contained in the coupled signal, to provide a detected signal; and control means responsible for the detected signal for controlling the equalizing means so that said frequency characteristics are controlled.

Claim 4

A feedforward amplifier, comprising: oscillator means for generating an oscillation signal with a controllable frequency; first coupling means for superimposing the oscillation signal on an input signal to provide a superimposed signal; distributor means for distributing the superimposed signal as a first distributed signal and a second distributed signal; equalizing means for adjusting frequency characteristics of both amplitude and phase of the first distributed signal to provide an adjusted signal; amplifying means for amplifying the adjusted signal to provide an amplified signal; second coupling means for coupling the second distributed signal with a phase-reversed signal of the amplified signal to provide a coupled signal; detecting means for detecting the oscillation signal, as it is contained in the coupled signal, to provide a detected signal; and control means responsible for the detected signal for controlling the equalizing means so that said frequency characteristics are controlled.

Claim 5

A feedforward amplifier in accordance with claim 2, wherein the control means controls the oscillator means so that said controllable frequency is controlled dependent on the detected signal.

Claim 6

A feedforward amplifier, comprising: first oscillator means for generating a first oscillation signal with a controllable first frequency; first coupling means for superimposing the first oscillation signal on an input signal to provide a first superimposed signal; distributor means for distributing the first superimposed signal as a first distributed signal and a second distributed signal; first equalizing means for adjusting first frequency characteristics of both amplitude and phase of the first distributed signal to provide a first adjusted signal; first amplifying means for amplifying the first adjusted signal to provide a first amplified signal; second oscillator means for generating a second oscillation signal with a controllable second frequency; second coupling means for superimposing the second oscillation signal on the first amplified signal to provide a second superimposed signal; third coupling means for branching the second superimposed signal to provide an extracted signal; fourth coupling means for coupling a phase-reversed signal of the extracted signal with the second distributed signal to provide a first coupled signal; second equalizing means for adjusting second frequency characteristics of both amplitude and phase of the first coupled signal to provide a second adjusted signal; second amplifying means for amplifying the second adjusted signal to provide a second amplified signal; fifth coupling means for coupling a phase-reversed signal of the second amplified signal with the second superimposed signal to provide a second coupled signal; first detecting means for detecting the first oscillation signal, as it is contained in the first coupled signal, to provide a first detected signal; first control means responsible for the first detected signal to control the first equalizing means so that said first frequency characteristics are controlled; second detecting means for detecting the second oscillation signal, as it is contained in the second coupled signal, to provide a second detected signal; and second control means responsible for the second detected signal to control the second equalizing means so that said second frequency characteristics are controlled.

Claim 7

A feedforward amplifier, comprising: first oscillator means for generating a first oscillation signal with a controllable first frequency; first coupling means for superimposing the first oscillation signal on an input signal to provide a first superimposed signal; distributor means for distributing the first superimposed signal as a first distributed signal and a second distributed signal; first equalizing means for adjusting first frequency characteristics of both amplitude and phase of the first distributed signal to provide a first adjusted signal; first amplifying means for amplifying the first adjusted signal to provide a first amplified signal; second oscillator means for generating a second oscillation signal with a controllable second frequency; second coupling means for superimposing the second oscillation signal on the first amplified signal to provide a second superimposed signal; third coupling means for branching the second superimposed signal to provide an extracted signal; fourth coupling means for coupling a phase-reversed signal of the extracted signal with the second distributed signal to provide a first coupled signal; second equalizing means for adjusting second frequency characteristics of both amplitude and phase of the first coupled signal to provide a second adjusted signal; second amplifying means for amplifying the second adjusted signal to provide a second amplified signal; fifth coupling means for coupling a phase-reversed signal of the second amplified signal with the second superimposed signal to provide a second coupled signal; first detecting means for detecting the first oscillation signal, as it is contained in the first coupled signal, to provide a first detected signal; first control means responsible for the first detected signal to control the first equalizing means so that said first frequency characteristics are controlled; second detecting means for detecting the second oscillation signal, as it is contained in the second coupled signal, to provide a second detected signal; and second control means responsible for the second detected signal to control the second equalizing means so that said second frequency characteristics are controlled.

Claim 8

A feedforward amplifier in accordance with claim 4 further comprising: first delay means connected between the third and fifth coupling means, the first delay means equivalent to a sum of signal delays at the second equalizing means and the second amplifying means; and second delay means coupled upstream of the fourth coupling means for delaying the second distributed signal, the second delay means equivalent to a sum of signal delays at the first equalizing means and the first amplifying means.

Claim 9

A feedforward amplifier in accordance with claim 4 wherein: the first control means controls the first oscillator means so that said first controllable frequency is controlled in dependence on the first detected signal; and the second control means controls the second oscillator means so that said second controllable frequency is controlled in dependence on the second detected signal.