Feed-forward amplifier with simple resistive coupling

Claim 1

A feed-forward amplifier for amplifying electromagnetic wave signals comprising: signal splitting means for dividing an input signal into first and second portions and applying said portions to first and second paths, respectively, said first path including a main amplifier for producing an amplified replica of said input signal, said amplified replica inherently including error components introduced by said main amplifier, signal tapping means connected to said main amplifier for tapping off a portion of said amplified replica and applying it to a third path, first signal combining means connected to said second and third paths for effecting subtraction of said second input signal portion from said amplified replica portion to produce an error signal substantially proportional to said error components, and for preventing feedback from said third path to said second path, error amplifying means connected to said first signal combining means for amplifying said error signal, and second signal combining means connected to said first path and said error amplifying means for effecting subtraction of said error components from said amplified replica to produce a substantially distortion-free output signal, Characterized in that said main amplifier has an output port with substantially zero output impedance, said signal tapping means comprises a resistive splitting junction formed at said output port, said error amplifying means has an input port with substantially zero input impedance, and said first signal combining means comprises a resistive summing junction formed at said input port, said third path introducing substantially zero phase shift between said output and input ports.