FEED FORWARD CIRCUIT AND A METHOD FOR ALIGNING AND BALANCING THE SAME

摘要

An improved feed forward circuit and a method of aligning and balancing the improved feed forward circuit. The feed forward circuit includes a first circuit loop to isolate signal noise and distortion and a second circuit loop to reduce signal noise and distortion. The first circuit loop and the second circuit loop have directional coupler means, amplification means, and delay means. The first circuit loop and the second circuit loop are interconnected through a pair of common directional coupler means having common balance circuitry connected therebetween. The first circuit loop has a signal input terminal and an input test terminal and the second circuit loop has a signal output terminal and an output test terminal. The improvement in the feed forward circuit includes a pair of additional directional coupler means. One of the additional directional coupler means is connected with the first circuit loop with the input test terminal and the other additional directional coupler means is connected with the second circuit loop with the output test terminal. The additional directional coupler means is operable to promote an accurate alignment and balance of the feed forward circuit and improve gain flatness and reduce signal distortion during operation thereof. A method is also provided for aligning and balancing of a feed forward circuit including the above described components. The presence of the additional directional coupler means in the improved feed forward circuit substantially reduces the magnitude of any undesirable signal present during alignment and balancing to promote an accurate alignment and balancing of the feed forward circuit.