Cascaded error correction in a feed forward amplifier

Claim 1

A feed forward amplifier system having a final output point, and comprising: means for receiving an input message signal; a main amplifier for amplifying the input message signal while inherently introducing a first error; a first comparison loop including a first delay element for receiving the input message signal, and a first comparison circuit for comparing a sample of the thus-delayed input message signal with a sample of the amplified but erroneous message signal to produce a signal that independently represents the first error; a first cancellation loop having a first error amplifier operated at a reduced power level which receives the first error signal and while amplifying the first error signal also introduces a second error; a second comparison loop including a second delay element for receiving the first error signal, a second comparison circuit for receiving a sample of the output of the first error amplifier that now contains both errors, and for comparing those two signals to then provide a signal that independently represents the second error; a second cancellation loop including a third delay element for delaying the output of the first error amplifier, a second error amplifier for amplifying the second error signal, and a first cancellation circuit for combining the amplified second error signal from the second error amplifier and the output of delay element to provide a modified and amplified version of the first error signal from which the second error has now been cancelled; the first cancellation loop having a single delay means for delaying the amplified input message signal as it passes toward the final output point, and also including a second cancellation circuit for injecting the thus-modified and amplified version of the first error signal together with the delayed and amplified input message signal into the final output of the amplifier system to provide a corrected output message signal; and wherein both the first error amplifier and the second error amplifier are in thermal communication with a common heat sink, and which further includes a single temperature sensor having associated control means for compensating both the amplitude drift and the phase drift of both the first error amplifier and the second error amplifier.