High-gain high-isolation CMFB stacked-LO subharmonic gilbert mixer using SiGe BiCMOS technology

A 5.2-GHz SiGe BiCMOS stacked-LO-stage CMFB (common mode feedback) subharmonic mixer is demonstrated in this article. The stacked-LO-stage and the active loads are used to improve the 2LO-RF isolation and the conversion gain, respectively. The SiGe mixer includes five levels of transistors stacked together at the supply voltage of 3.3 V because of the low knee-voltage characteristic of the SiGe HBTs (heterojunction bipolar transistors). The mixer demonstrated achieves 23 dB conversion gain and −78 dB 2LO-RF isolation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1214–1216, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22398