Abstract: A feedforward amplifier system including a main amplifier and first and second error amplifiers, and wherein the first error amplifier is itself a feedforward amplifier whose operation is corrected by the second error amplifier. With appropriate selection of circuit components the operating power required by the amplifier system, and hence the size of the package in which it is contained, may be reduced up to one-third.

Abstract: A feed forward amplifier circuit which includes a main amplifier, an error correction circuit producing a message error signal, an error amplifier for producing an amplified message error signal that is then subtracted from the amplified and distorted message signal output of the main amplifier prior to a final output circuit, a negative feedback circuit coupled to the final output circuit responsive to a test signal for compensating and minimizing drift in the operation of the error amplifier, and circuitry associated with the negative feedback circuit for detuning performance of the error correction circuit at the test frequency so as to improve the overall circuit performance across a desired operating frequency band while diminishing its performance at the test signal frequency.

Abstract: A feed forward cancellation amplifier system for amplifying radio frequency telephony signals, including a main amplifier, an error correction circuit producing a message error signal, an error amplifier for producing an amplified message error signal that is then subtracted from the amplified and distorted message signal output of the main amplifier prior to a final output circuit, a negative feedback circuit responsive to a test signal for compensating and minimizing variation or drift in the operation of the error amplifier, the error correction circuit including a vector modulator responsive to modified quadrature vector components of the message error signal for producing a single voltage vector error signal, and the negative feedback circuit including an I & Q network for modifying the quadrature vector components of the error signal in the error correction circuit.The preferred form of the invention utilizes PIN diodes to provide voltage controlled attenuators in the vector modulator.