A Fast fc Automatic Tuning Circuit with Wide Tuning Range for WCDMA Direct Conversion Receiver Systems

Osamu WATANABE  Rui ITO  Shigehito SAIGUSA  Tadashi ARAI  Tetsuro ITAKURA  

IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.6   pp.1247-1252
Publication Date: 2007/06/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.6.1247
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
WCDMA,  DCR,  lowpass filter,  fc automatic tuning,  

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A fast fc automatic tuning circuit suitable for WCDMA systems is proposed. The circuit employs master-slave architecture using digitally controlled Gm-C filter for avoiding long transient response. The tuning feedback loop contains a 2-bit up-down counter ADC for fast tuning operation. Furthermore, to avoid degradation of fc tuning accuracy due to reference feedthrough, an analog loop filter with notch located near reference frequency is used. The fast fc automatic tuning circuit is fabricated in a SiGe BiCMOS process. The tuning time within 200 µs is achieved for 35 chips from 2 lots and the standard deviation of 25.5 kHz is obtained for the average fc of 2.12 MHz.