A feedforward S-band MIC amplifier system

A 2.2 GHz high-power feedforward amplifier system has been designed and fabricated, which has an RF gain of 30 dB and delivers an output power of 1.25 W with all IM distortion products at least down 50 dB from the carrier level. The power amplifiers and passive circuit components used in this system are all realised in thin-film hybrid form. The theoretical development of the system is described. The result of the temperature stability tests is given. The computer optimisation technique with multiband weighting functions used throughout the amplifier design process is presented. Finally, practical applications and a comparison of the advantages and drawbacks of this (feedforward) amplifier system with those produced by using the conventional (back-off) approach are discussed.