A fully integrated 5.2 GHz SiGe HBT upconversion micromixer using: lumped balun and LC current combiner

A small and compact 5.2 GHz upconversion Gilbert micromixer using 0.35 μm SiGe HBT technology is demonstrated in this paper. The upconversion micromixer has a broadband matched single-ended IF input port. A lumped-element rat-race hybrid is inserted in the LO input stage to maintain LO phase accuracy. A passive LC current combiner is used to convert the micromixer differential output into a single-ended output and double the output current. Thus, the IF port, LO port and RF port of the upconverter are single-ended, and the stand-along upconverter is suitable for hybrid RF system applications. The fully matched high linearity micromixer has the conversion gain of -1 dB, OP_1dB of -10 dBm, OIP₃ of 6 dBm when input IF=300 MHz, LO=4.9 GHz and output RF=5.2 GHz. The IF input return loss is better than 10 dB for frequencies up to 20 GHz while the RF output return loss is better than 13.5 dB for frequencies up to 20 GHz. The supply voltage is 3.3 V, the current consumption is 11.5 mA, and the die size is 0.98×0.83 mm² with 6 integrated on-chip inductors.