A 16 W solid state MMIC X-band amplifier for TWT replacement

This paper reports the use of MMIC power amplifier modules in an X-band power amplifier for the replacement of travelling wave tubes (TWTs) in terrestrial point to point digital communication links. The amplifier modules use MMIC MESFET technology to ensure high reliability and repeatability in manufacture. The use of MMICs results in an easily manufacturable power module, requiring no tuning or phase matching, at low cost. The complete amplifier uses optimum power combiners designed using state of the art electromagnetic simulation software. The solid state amplifier reports improved linearity and increased lifetime compared to the equivalent TWT. The solid state amplifier achieves a P-1 dB of greater than 16 W CW and at a power output of 6 W results in intermodulation products of less than -42 dBc in the transmitter system. The amplifier and its associated power supply are also of lower cost than a replacement travelling wave tube.