High Power Distributed Amplifier Using MBE Synthesized Material

The main limitations of the output power of a distributed amplifier are the gate line loss and the gate-to-drain breakdown voltage. A novel circuit concept to reduce the gate loss using series capacitors on the gate feeding lines has been implemented. The device breakdown voltage has been improved by using an MBE grown material with two layers (low doped gate buffer layer and usual active layer). A monolithic GaAs distributed amplifier using 6 x 300 µm FETs has achieved an output power of 800 mW with 4dB gain. The power added efficiency was about 15%.