A decade bandwidth, low voltage, medium power Class B push-pull Si/SiGe HBT power amplifier employing through-wafer vias

We report a 0.5-5 GHz, 2 V class B push-pull power amplifier in a through-wafer via Si/SiGe HBT process. The amplifier utilized a small, low loss, broadband balun and a coupled spiral inductor transformer. Power added efficiencies greater than 40% from 1 GHz to 4 GHz and greater than 30% from 0.5 to 5 GHz have been achieved. Small signal gain of greater than 13 dB and maximum output power of 22 dBm were realized from 0.5 GHz to 4 GHz with a 2 V supply voltage.