A monolithic SiGe heterojunction bipolar transistor gilbert upconverter with inductor-capacitor current mirror load and lumped-element rat-race balun

Abstract

A 5.2GHz upconversion Gilbert mixer with single-ended intermediate frequency (IF), local oscillator (LO), and RF ports is demonstrated using 0.35 mu m SiGe heterojunction bipolar transistor (HBT) technology. The upconverter has a single-ended IF port. In addition, a lumped-element rat-race hybrid is inserted in the LO input stage to maintain balanced LO signals. The physics of the lumped-element rat-race is discussed in this paper. A passive LC current mirror is used to convert the mixer's differential outputs into a single-ended output and double the output current. The design methodology of the LC current mirror and a new approach to improve the power gain with the output buffer are developed in this paper. The fully matched Gilbert upconverter has the conversion gain of -1dB, OP1dB of -10dBm and OIP3 of 6dBm when input IF=300MHz, LO = 4.9GHz and output RF = 5.2GHz. The LO-IF isolation is -36dB and the LO-RF isolation is -39dB. The supply voltage is 3.3V, the current consumption is 11.5mA, and the die size is 0.98 x 0.83 mm(2) with six integrated on-chip inductors.