A fast f c  automatic tuning circuit suitable for WCDMA systems is proposed. The circuit employs master-slave architecture using digitally controlled G m -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 f c  tuning accuracy due to reference feedthrough, an analog loop filter with notch located near reference frequency is used. The fast f c  automatic tuning circuit is fabricated in a SiGe BiCMOS process. The tuning time within 200μs is achieved for 35 chips from 2 lots and the standard deviation of 25.5 kHz is obtained for the average f c  of 2.12 MHz.
['Osamu Watanabe', 'Rui Ito', 'Shigehito Saigusa', 'Tadashi Arai', 'Tetsuro Itakura']
A Fast fc Automatic Tuning Circuit with Wide Tuning Range for WCDMA Direct Conversion Receiver Systems