IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Special Section on Analog Circuit Techniques and Related Topics
A Low-Noise Amplifier for WCDMA Terminal with High Tolerance for Leakage Signal from Transmitter
Ryuichi FUJIMOTOGaku TAKEMURAMasato ISHIITakehiko TOYODAHiroshi TSURUMI
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2008 Volume E91.A Issue 2 Pages 521-528

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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 0.12dB.

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© 2008 The Institute of Electronics, Information and Communication Engineers
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