0.4-5.8 GHz SiGe-MMIC Quadrature Modulator Employing Self Current Controlled Mixer for Cognitive Radio

Shintaro SHINJO
Fumiki ONOMA
Hiroshi HARADA

IEICE TRANSACTIONS on Communications   Vol.E92-B    No.12    pp.3701-3710
Publication Date: 2009/12/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.3701
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Dynamic Spectrum Access)
Category: Wideband RF Systems
microwave,  MMIC transmitters,  MMIC mixers,  mobile communication,  modulation,  wireless LAN,  

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A 0.4-5.8 GHz SiGe-MMIC quadrature modulator (Q-MOD) employing a self current controlled mixer for cognitive radio is described. The self current controlled mixer consists of a Gilbert cell mixer and a self current control circuit which is composed of both a current feedback circuit and an output buffer amplifier. The self current control circuit automatically controls the mixer current according to the output power level, and improves the linearity over wide radio frequency (RF) range. Simulation results show that the proposed Q-MOD realizes 1 dB compression point (P1 dB) improvement of more than 3.0 dB compared to the conventional Q-MOD at the frequencies of 0.4, 0.8, 1.95, 5.2 and 5.8 GHz. The fabricated Q-MOD achieves P1 dB improvement of more than 2.8 dB under the same condition. It also improves the output power with error vector magnitude (EVM) of 3.0% (Pout@EVM=3.0%), and achieves the Pout improvement of more than 2.7 dB under the modulation conditions of UHF wireless system (OFDM/16QAM, 0.4 GHz), W-CDMA (HPSK/QPSK, 0.8 GHz/1.95 GHz) and wireless-LAN (OFDM/64QAM, 5.2 GHz/5.8 GHz).