ENHANCED EFFICIENCY FEED FOWARD POWER AMPLIFIER WITH DELAY MISMATCHED ERROR CANCELLATION LOOP

摘要

A delay mismatched feed forward power amplifier is disclosed. Loop 1 includes a main amplifier (215) and is used to derive a carrier cancelled sample of the main amplifier output. Loop 2 includes an error amplifier (400) used to amplify the carrier cancelled signal derived from Loop 1 operation in order to cancel distortion products generated due to the nonlinear nature of the main amplifier. Loop 2 also utilizes a very short Loop 2 delay line (225). A significant efficiency gain is provided due to reduced output power losses associated with the Loop 2 delay line (225). Lower output losses also results in lower distortion levels produced by the main amplifier (215). This, in turn, reduces the size and performance requirements placed on the error amplifier (400). A smaller and more efficient error amplifier (400) is employed resulting in further amplifier system efficiency improvement. The delay mismatch is compensated by a third control loop, a special adaptive control algorithm or a combination thereof.