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A Low LO Leakage and Low Power LO Buffer for Direct-Conversion Quadrature Demodulator
Toshiya MITOMO Osamu WATANABE Shoji OTAKA Ryuichi FUJIMOTO Shunji KAWAGUCHI
IEICE TRANSACTIONS on Electronics
Publication Date: 2005/06/01
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit and Device Technologies)
LO buffer, quadrature demodulator, direct-conversion, self mixing, DC offset,
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A DC offset caused by self-mixing is a serious problem for direct-conversion receivers. Local oscillation (LO) leakage via quadrature demodulators (QDEMOD) must be suppressed in order to achieve a low DC offset. An LO buffer which drives QDEMOD mainly causes the LO leakage. We proposed an LO buffer which has a high-pass frequency response with small occupied area and low current consumption. A QDEMOD using the proposed LO buffer is fabricated using a SiGe BiCMOS process. Measured low LO leakage of -70 dBm is achieved, which is 10 dB lower than that of a QDEMOD with a conventional LO buffer. This measured result indicates that the proposed LO buffer is suitable for QDEMODs for direct-conversion receivers.