Patent ID: 6998916
Filing Date: 2006-02-14
Classification: H03F

Abstract:
1. A feed forward amplifier, comprising: an input for receiving an RF signal; a main amplifier receiving and amplifying said RF signal; a gain adjuster coupled between the RF input and the main amplifier; a main amplifier output sampling coupler; a first delay coupled to the input and providing a delayed RF signal; a carrier cancellation combiner coupling the delayed RF signal to the sampled output from the main amplifier; a test coupler for sampling the output of the carrier cancellation combiner; an error amplifier receiving and amplifying the output of the carrier cancellation combiner; a second delay coupled to the output of the main amplifier; an error coupler combining the output from the error amplifier and the delayed main amplifier output from the second delay so as to cancel distortion introduced by the main amplifier; an output coupled to the error coupler output and providing an amplified RF signal; and an adaptive controller, coupled to the test coupler, for controlling the gain adjuster setting to provide a gain adjustment which is offset from a gain adjustment which maximizes carrier cancellation at the carrier cancellation combiner, which offset is adjustable by changing the floor of a gain adjustment cost function.