A Low-Noise Amplifier for WCDMA Terminal with High Tolerance for Leakage Signal from Transmitter

Ryuichi FUJIMOTO  Gaku TAKEMURA  Masato ISHII  Takehiko TOYODA  Hiroshi TSURUMI  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E91-A   No.2   pp.521-528
Publication Date: 2008/02/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e91-a.2.521
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
Category: 
Keyword: 
low-noise amplifier,  LNA,  WCDMA,  TX leakage signal,  noise frequency conversion,  noise figure NF,  

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Summary: 
Since a receiver (RX) and a transmitter (TX) are operated simultaneously in a WCDMA transceiver, noise and intermodulation distortion performances of a low-noise amplifier (LNA) are degraded by a large leakage signal from the TX. The degradation of the distortion due to the large leakage signal from the TX has been reported in some previous works, but to our best knowledge, there are no reports about the degradation of noise figure (NF) in a LNA due to the large leakage signal from the TX. In this paper, a 900-MHz LNA for WCDMA terminal with high tolerance for a leakage signal from the TX is proposed. Suitable designs of an input matching circuit and a trap circuit are adopted to improve the tolerance for the leakage signal from the TX. The LNA using the proposed techniques is fabricated using SiGe-BiCMOS process. The measured degradation of NF due to the leakage signal from the TX is suppressed to only 0.12 dB.