A Monolithic GaN based Supply Modulator with Dual-Antibootstrap Level Shifter for Envelope Tracking Application
We report a Monolithic GaN based Supply Modulator (SM) and verify it for envelope tracking power amplifier (ET-PA). A signal amplifier is integrated in the SM and a novel Dual-Antibootstrap Level Shifter (D-ALS) is introduced to reduce the power consumption. As a result, the SM can be controlled by a low swing digital signal. The SM achieves a total efficiency of 76%, output power of 4.2W with 100MHz switching frequency under a 256QAM signal with 20MHz bandwidth and 6.5dB PAPR. Furthermore, a continuous Class-F power amplifier is supplied by the SM for a verification of ET-PA. The overall efficiency of the ET-PA was increased by 8% compared to the PA with fixed supply voltage under 30.6dBm output power at 2.7GHz with 20MHz bandwidth and 6.5dB PAPR. To the author's best knowledge, this is the first GaN ET-PA supporting a digital control signal with a low swing as small as 0.7V.