Patent ID: 7106134

Claim:
A feed forward amplifier, comprising: an RF input for receiving an RF signal having an RE carrier and a modulation bandwidth of at least 10 MHz; a predistortion circuit receiving and predistorting said RF input signal; a main amplifier receiving and amplifying said predistorted RF signal, said main amplifier comprising an active device and a bias circuit coupled to a DC power supply, said bias circuit having a transfer function having a plurality of transmission zeros spaced across the modulation bandwidth so as to substantially eliminate amplifier memory effects; a main amplifier output sampling coupler; a first delay coupled to the RF input and providing a delayed RF signal; a carrier cancellation combiner coupling the delayed RF signal to the sampled output from the main amplifier; 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 injection 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; and an RF output coupled to the error injection coupler output and providing an amplified RF output.