A high isolation CMFB downconversion micromixer using 0.18-/spl mu/m deep n-well CMOS technology

• Published in: IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, 2003 pp. 619 - 622
• Main Authors: Meng, C.C., Xu, S.K., Wu, T.H., Chao, M.H., Huang, G.W.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2003
• Subjects: Chaotic communication; CMOS technology; Degradation; Frequency; Gain; Isolation technology; Laboratories; Mixers; MOSFETs; Transconductance
• ISBN: 0780376943; 9780780376946
• ISSN: 1529-2517; 2375-0995
• DOI: 10.1109/RFIC.2003.1214023

CMOS deep n-well technology can eliminate body effects of NMOS transistors and improve LO-IF and LO-RF isolation in a Gilbert micromixer. A 37 dB LO-IF and 38 dB LO-RF isolation downconversion micromixer with 19 dB conversion gain, IP/sub 1dB/=-19.5 dBm and IIP/sub 3/=-12.5 dBm when RF=2.4 GHz and LO=2.25 GHz is demonstrated in this paper by using 0.18 /spl mu/m deep n-well CMOS technology. The input return loss and output return loss are better than 15 dB for frequencies up to 6 GHz. On the other hand, a downconversion micromixer without deep n-well has almost identical power performance but achieves only 20 dB LO-IF isolation and 21 dB LO-RF isolation even if two kinds of mixers are fabricated in adjacent areas of the same wafer. The downconversion micromixer used here has an intrinsically single-to-differential input stage and active differential PMOS loads to increase IF differential gain while CMFB is used to stabilize bias points. An IF differential amplifier converts differential output into a single-ended output. Finally, an off-chip rat-race coupler provides balanced LO signals to facilitate isolation measurement.