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IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences 2008 E91-A(2):521-528; doi:10.1093/ietfec/e91-a.2.521
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Copyright © 2008 The Institute of Electronics, Information and Communication Engineers

Special Section on Analog Circuit Techniques and Related Topics -- Papers

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

Ryuichi FUJIMOTO1, Gaku TAKEMURA1, Masato ISHII1, Takehiko TOYODA1 and Hiroshi TSURUMI1

1 The authors are with the Semiconductor Company, Toshiba Corp., Yokohama-shi, 247-8585 Japan. E-mail: ryuichi.fujimoto{at}toshiba.co.jp


  Abstract

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.

Key Words: low-noise amplifier, LNA, WCDMA, TX leakage signal, noise frequency conversion, noise figure NF

Manuscript received July 2, 2007.


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