SiGe HBT Gilbert Downconverter With an Integrated Miniaturized Marchand Balun for UWB Applications

A 15.5-dB conversion gain 0.35-mum SiGe HBT Gilbert mixer with the lumped-element Marchand balun for 3.1 GHz to 10.6 GHz UWB applications is implemented using standard silicon processes. This mixer has the 1.5-GHz IF 3-dB bandwidth as well as the 15.8-dB noise figure. The balun size is only 0.25 mm times 0.5 mm. Because of the balanced structure of the Marchand balun, the magnitude imbalance and phase difference of outputs are below 1 dB and about 184deg, respectively. In the present of a lossy substrate, the dissipated loss of the balun is still less than 4 dB thanks to the advantage of the lumped-element technique. The total current consumption of the entire mixer is 13.9 mA at 5 V voltage supply while the chip size including probing pads is 1 mm times 0.9 mm.