A GaN power amplifier for 100 VDC bus in GPS L-band

An innovative approach in RF GaN technology suitable for Global Positioning System (GPS) L-band transmitters is presented. The solution operates directly from the 100 VDC voltage bus without the need for a DC-DC step-down converter to typical 28 V or 50 V. It is based on a mature GaN HEMT process which is radiation tolerant and reliable for space applications. The prototype single stage amplifier reported in this paper operates at 100 V bias and achieves 100 W CW output power with 19 dB gain and high efficiency > 60% at the L1 frequency band of 1575 ± 50 MHz. Preliminary results at L2 and L5 GPS bands are also reported. The demo amplifier consists of a single die with 12 mm gate periphery in a hermetic package. Higher power can easily be attained by utilizing multiple chips in one package. The proposed technology reduces SWaP figure of merit and simplifies the design of transmitters for GPS satellites.