The Development of a High Power SP4T RF Switch in GaN HFET Technology

The development of a high power single-pole four throw (SP4T) hybrid switch using AlGaN/GaN heterostructure field effect transistors (HFETs) on Si substrate is reported for the first time for applications up to 1.5 GHz. The off-state capacitance of a single-gate GaN based HFET is 250 fF and the on-state resistance is 4.1 at a gate length of 0.7 m and a width of 1 mm. The hybrid SP4T switch with a size of 44 mm was implemented for system applications of three transmit paths and a receiver, of which each was configured with a series-shunt self-biased configuration. The switch has achieved an insertion loss of 1.4 dB with power handling of 43 dBm at the transmitter paths and an optimized isolation of better than 25 dB at the receiver path at 1.5 GHz. In addition, a high voltage switch driver using the GaN HFET technology was designed with an input control voltage of 0/4 V to provide an output voltage of 0/26 V. This development provides a baseline design for our next generation monolithic microwave integrated circuit switches in GaN technology.