A broadband power amplifier module for high bit-rate SONET/SDH transmission channels, such as OC-192 and OC-768 applications. The power amplifier module, or also frequently referred to as modulator driver module, comprises amplifiers connected in series to amplify an input signal. A bias tee circuit...http://www.google.co.uk/patents/US6639461?utm_source=gb-gplus-sharePatent US6639461 - Ultra-wideband power amplifier module apparatus and method for optical and electronic communications
