A 10-W, 6-GHz, GaAs IMPATT Amplifier for Microwave Radio Systems

I M P A T T diodes provide a practical means of generating watts of cw microwave power. These devices are now commonly used in transmitter power amplifiers at 6 GHz and higher frequencies. For short-haul radio systems, an output power of 1 to 2 W, which can be obtained using a single diode, 1 is often sufficient. However, for long-haul systems, 10 W is a typical output power requirement, and the traveling-wave tube has been the indispensable selection. This much power can be obtained from multiple-IMPATT-diode circuits, especially when GaAs diodes are used. GaAs diodes have greater efficiency and lower noise than Si diodes, and this latter quality is equally important in meeting long-haul objectives. This paper describes the circuit configuration used to meet the long-haul transmission objectives with a minimum number of I M P A T T diodes, corresponding to highest overall efficiency. The diodes have conventional flat-doping profiles. The higher-efficiency, modifiedRead-profile diodes were not available at the onset of this development, so they are not included in this study.