Compact 5.2-GHz GaInP/GaAs HBT Gilbert upconverter using lumped rat-race hybrid and current combiner

A compact 5.2-GHz Gibert upconversion mixer is demonstrated using the 2-μm GaInP/GaAs heterojunction bipolar transistor (HBT) technology. A miniature lumped-element rat-race hybrid and an LC current combiner are used in the LO port and the RF port of the upconversion Gilbert mixer, respectively. The effect of the LC current combiner with inductor loss is established in this letter. An active IF balun is incorporated in the Gilbert upconverter with no extra power consumption. The fully integrated Gilbert upconverter has conversion gain of 1 dB, OP/sub 1 dB/ of -10 dBm, and OIP3of 2dBm when input IF=300 MHz, LO=4.9 GHz, and output RF=5.2 GHz.