Design methodology for the optimization of transformer-loaded RF circuits

In this paper a design methodology for the optimization of transformer-loaded RF circuits is discussed and a simplified equation for the maximum available output power is presented. The optimization procedure is based on a novel figure of merit for the integrated transformer, which was introduced to quantify its performance when operated as a tuned load. By means of the proposed approach, a highly linear up-converter for 5-GHz wireless LAN applications was implemented in a 40-GHz-f_T SiGe HBT technology. The circuit achieves an output 1-dB compression point of 4.5 dBm and a power gain of 18 dB, while drawing only 34 mA from a 3-V power supply.