Delay mismatched feed forward amplifier system using penalties and floors for control

A delay mismatched feed forward amplifier, comprising:

• an input for receiving an RF input signal;
• a first control loop coupled to the input and comprising a main amplifier, a main amplifier sampling coupler, a delay element, and a cancellation combiner;
• a second control loop coupled to the first control loop and comprising a first signal path, a second signal path comprising an error amplifier, and an error coupler coupling the first and second signal paths, said first and second paths having a delay mismatch;
• an output coupled to the error coupler;
• a pilot signal source coupled to the first control loop and providing a pilot signal having a frequency;
• means for detecting the pilot signal at the output;
• and
• means, coupled to the means for detecting, for controlling the second control loop to stabilize second control loop cancellation at a center frequency offset from the pilot signal frequency and adjacent the center of the RF signal bandwidth.

A method for amplifying an RF input signal employing feed forward compensation, comprising:

• receiving an RF input signal and providing said signal on a main signal path;
• injecting a pilot signal into said main signal path;
• sampling the RF input signal and providing the sampled RF input signal on a second signal path;
• amplifying the signal on said main signal path employing a main amplifier;
• sampling the main amplifier output;
• delaying the sampled RF input signal on the second signal path;
• coupling the delayed RF input signal to the sampled output from the main amplifier so as to cancel at least a portion of a carrier component of said sampled output from the main amplifier and provide a carrier canceled signal having a distortion component;
• amplifying the carrier canceled signal employing an error amplifier to provide an error signal;
• combining the error signal and the output of the main amplifier so as to cancel distortion introduced by the main amplifier and providing an amplified RF output;
• detecting the pilot signal in said amplified RF output;
• adjusting the phase of the signal input to said error amplifier by a variable phase setting;
• and
• controlling said phase adjusting to a steady state setting offset from a setting which minimizes the detected pilot signal.