A switching-mode amplifier for class-S transmitters for clock frequencies up to 7.5 GHz in 0.25µm SiGe-BiCMOS

This paper presents the first voltage mode H-bridge switching amplifier in a fast complementary SiGe-technology for frequencies in the GHz range. The amplifier is suited as a driver for a high power GaN amplifier in class-S transmitters. It can be operated with pseudo-random digital pulse trains up to 7.5 Gbit/s. The measured broadband output power for a rectangular drive signal with a 50% duty cycle and a frequency of 2 GHz is about 148 mW. The efficiency of the switching stage including its two-stage inverter driver is about 43%. Including the input current-mode-logic (CML) stage, the PAE is about 30%.