A feed forward cancellation amplifier system for amplifying radio frequency telephony signals, including a main amplifier, an error correction circuit producing a message error signal, an error amplifier for producing an amplified message error signal that is then subtracted from the amplified and distorted...http://www.google.de/patents/US5508657?utm_source=gb-gplus-sharePatent US5508657 - Feed forward cancellation amplifier utilizing dynamic vector control
