A method and a circuit for power amplification over a wide frequency range based upon the use of minimum-rating filters or matching networks, negative-component signal processing, and single or multiple amplifiers. The filters and matching networks are preferably designed to minimize the required ratings...http://www.google.de/patents/US6552634?utm_source=gb-gplus-sharePatent US6552634 - Wideband, minimum-rating filters and multicouplers for power amplifiers
