Linearization of an amplifier employing modified feedforward correction

A method of linearizing an output amplifying means having a non-linear signal response characteristic and located in a multi-stage amplifier network between a signal source and a load by providing feedforward correction to a preceding amplifying means comprising the steps of:

• selecting a preceding amplifying means within said network wherein said preceding amplifying means exhibits a non-linear signal response characteristic similar to that of said output amplifying means;
• applying an input signal to said selected preceding amplifying means to generate an intermediate output signal therefrom in which the intermediate output signal normally has a signal difference from that of said input signal as a function of the non-linear signal response characteristic of said selected preceding amplifying means;
• combining at least a portion of said input signal with at least a portion of said intermediate output signal to obtain therefrom an error signal which represents said signal difference;
• combining said error signal with said intermediate output signal in a manner so as to obtain a corrected intermediate output signal;
• applying said corrected intermediate output signal to said output amplifying means to obtain an output signal therefrom;
• adjusting said error signal in a direction to provide an overcorrected said intermediate output signal which has been overcorrected by an amount sufficient to compensate for the non-linear signal response characteristic of said output amplifying means whereby said output signal from said output amplifying means is essentially linearly related to said input signal;
• and
• including the step of up-converting the output frequency of said preceding amplifying means to a higher frequency than the normal operating frequency of said preceding amplifying means.