Feedforward amplifiers
AssigneeThe Marconi Company Limited
InventorRoger E. J. Gerard
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Abstract
A feedforward amplifier is designed to exhibit particularly linear transfer characteristics in which distortion signals introduced by the amplifier itself are monitored and the phase and amplitude characteristics of respective adaptive equalizers are modified to reduce any distortions at these points. A reference signal is injected directly into a main amplifying element so that it appears at the output terminal as though it were an amplified induced distortion. The characteristics of the amplifier are adaptively modified to eliminate the reference signal from the output signal.
Claims12
A feedforward amplifier including a main amplifying device coupled between an input terminal at which an input signal is received and an output terminal at which an amplified replica of the input signal is provided;
- comparison means for comparing a signal derived from the output of the main amplifying device with the input signal to produce a difference signal representative of distortions introduced by said main amplifying device;
- combiner means for combining an amplified difference signal with the output of the main amplifying device to compensate for these distortions;
- means for injecting a reference signal into the main amplifying device and for monitoring the amplified signal present at said output terminal;
- and means for adjusting the transfer characteristic of the feedforward amplifier to minimise the amplitude level of said reference signal at said output terminal.
Dependencies are inferred from the claim text.