题目/Title：A 0.18-um CMOS GFSK Analog Front End Using a Bessel-Based Quadrature Discriminator with On-Chip Automatic Tuning

作者/Author：
                        Baoyong Chi,Jinke Yao,Patrick Chiang,Zhihua Wang

期刊/Journal：IEEE Transactions on Circuits and Systems I-Regular Papers

年份/Issue Date：2009Nov.

卷（期）及页码/Volume（No.）&pages：Vol.56, No.11, pp. 2498 - 2510

摘要/Abstract：
A fully integrated 2-MHz Gaussian frequency-shift keying (GFSK) analog front end for low-IF receivers is presented. The analog GFSK demodulation uses a Bessel-based quadrature discriminator and a differentiator-based data decision circuit, eliminating the need for analog-digital converters while enabling high sensitivity and large frequency offset tolerance. The analog front end consists of a fifth-order Butterworth low-pass prefilter, a seven-stage limiter, a quadrature discriminator with a fourth-order Bessel phase-shift network, a fourth-order Butterworth low-pass postfilter, and a differentiator-based data decision circuit. The prefilter, Bessel phase shifter, postfilter, and differentiator are built using identical Gm-C cells and tuned across process variations with a single master-slave phase-locked loop. The GFSK analog front end is implemented in a 1.8-V 0.18-mum CMOS process, recovering 1-Mb/s input data from a 2-MHz GFSK signal with maximum frequency deviation of plusmn160-kHz, frequency offset tolerance from - 38% to +47%, and input sensitivity of -53 dBm and consuming 7 mA of current.