A high-power dual-gate GaN switching-amplifier in the GHz-range

A high efficient GaN switch-mode amplifier for Gbit data rates is presented. The design uses GaN HEMTs with a gate length of 250 nm. It consists of a dual-gate transistor configuration in the output stage. This allows an increase of supply voltage in order to increase the output power. If an increase of power is not required, device size can be reduced which comes along with a better RF-performance. The presented amplifier exhibits an output signal with peak-to-peak voltages up to 60 V and achieves a broadband output power of 17 W with a PAE of 79.5 % at 0.9 Gbps. Considering a bit rate of 5.2 Gbps, the corresponding values are 40 V, 4 W and 38.6 %. To the authors knowledge, the presented amplifier is the first GaN switch-mode amplifier with a dual-gate transistor in the output stage. Its measured results are the best concerning the combination of a high frequency and a high power at the same time.