Solid state power amplifier and travelling wave tube amplifier additive phase noise characterization at Ka-band operation

A Ka-band (31–36GHz) solid state power amplifier (SSPA) capable of producing more than 50 W of output power was developed by the Jet Propulsion Laboratory (JPL) using a novel 32-way combiner/splitter and 32 2W GaAs PHEMT MMIC modules [1]. Additionally, a 200 W travelling wave tube amplifier (TWTA) manufactured by L3 Communications was acquired and characterized. While these devices are typically not the primary sources of origin for phase noise in transponders, they will contribute phase noise and may add to system phase noise differently. Because information on Ka-band tube and solid-state amplifier additive phase noise performance was not available for these high-power Ka-band amplifiers, an investigation into the phase noise of the SSPA and TWTA was launched. Results indicate that the tested SSPA may have a lower close-in phase noise than the tested TWTA.