Title :
A frequency auto-tuning complex filter with 48dB gain tuning and 65dB DC-offset rejection
Author :
Tan, Junzhang ; Wang, Lijiong ; Chen, Dongpo ; Zhou, Jianjun
Author_Institution :
Center for Analog/RF Integrated Circuits (CARFIC), Shanghai Jiao Tong Univ., Shanghai, China
Abstract :
A 4th order Chebyshev complex filter with stop band zeros at the DC point for low-IF receivers´ applications using 0.18μm CMOS technology is proposed in this paper. Based on capacitor-OTA integrators, the designed ladder filter uses resistors instead of capacitors to realize the transmission zeros. The complex filter has a 0 to 48dB tunable gain (6dB per step) and over 65dB DC-offset rejection. A simple and fast frequency auto-tuning scheme with delay lock loop and binary search algorithm is utilized to auto-calibrate the pass-band bandwidth (4MHz) and center frequency (4MHz). The whole complex filter consumes 2.5mA from a 1.8V supply.
Keywords :
CMOS integrated circuits; Chebyshev filters; band-pass filters; calibration; circuit tuning; delay lock loops; integrated circuit design; low-pass filters; operational amplifiers; receivers; resistors; CMOS technology; DC point; DC-offset rejection; autocalibration; bandwidth 4 MHz; binary search algorithm; capacitor-OTA integrators; center frequency; current 2.5 mA; delay lock loop; fourth order Chebyshev complex filter; frequency autotuning complex filter; gain 0 dB to 48 dB; gain tuning; ladder filter; low pass filter; low-IF receivers; pass-band bandwidth; resistors; size 0.18 mum; stop band zeros; transmission zeros; voltage 1.8 V; Bandwidth; Capacitors; Chebyshev approximation; Gain; Low pass filters; Prototypes; Tuning;
Conference_Titel :
Solid-State and Integrated Circuit Technology (ICSICT), 2010 10th IEEE International Conference on
Conference_Location :
Shanghai
Print_ISBN :
978-1-4244-5797-7
DOI :
10.1109/ICSICT.2010.5667677
