Auto-transformer-based power amplifier with totem-pole driver

We present a fully integrated auto-transformer-based power amplifier with totem-pole driver exhibiting a very high bandwidth. In order to simplify the design process a structural analysis and optimization method for the transformer are presented as well as an analytical method to ensure the optimum load line at the transistor. The circuit was implemented in a 0.25 μm SiGe BiCMOS technology and was characterized on-waver and chip-on-board mounted. The measurement results prove a bandwidth of 800 MHz around 650 MHz. The output power at 1 dB compression point is 24.4 dBm with a power added efficiency of 38%. The circuit was also tested with DVB-T signals showing that not more than 5 dB back-off are required in order to fulfill the error vector magnitude requirements. In this case, the efficiency is more than 19%.