A Quadrature Demodulator for WCDMA Receiver Using Common-Base Input Stage with Robustness to Transmitter Leakage


IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.6   pp.1241-1246
Publication Date: 2007/06/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.6.1241
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
WCDMA receiver,  direct conversion,  quadrature demodulator,  common-base circuit,  

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A quadrature demodulator (QDEMOD) for WCDMA direct-conversion receiver using a common-base input stage is reported. A common-base input stage is robust to parasitic elements and is suitable for integrating on-chip matching circuits to realize small and low-cost RF front-end modules. However, a common-mode blocker signal, such as the transmitter (TX) leakage signal, degrades the noise performance due to DC current increase and intermodulation distortion of the TX leakage signal and noise. We propose a QDEMOD with a common-base input stage capable of suppressing the TX leakage signal using symmetrical inductors. The QDEMOD was fabricated using SiGe BiCMOS process with fT of 75 GHz. The measured results show that the NF degradation does not occur until the TX leakage signal input is larger than -10 dBm.