题目/Title：A multi-bit FIR filtering technique for two-point modulators with dedicated digital high-pass modulation path

作者/Author：
                        Xiaoyong Li,Woogeun Rhee,Wen Jia,Zhihua Wang

会议/Conference：ISCAS 2015

地点/Location：Lisbon, Portugal

年份/Issue Date：2015.24-27 May

页码/pages：pp. 894 - 897

摘要/Abstract：
This paper describes an effective way of relaxing the nonlinearity problem of the digitally-controlled oscillator (DCO) in the two-point modulator design. A separate coarse varactor array dedicated for the high-pass modulation significantly simplifies the nonlinearity calibration of the DCO with a few-bit control. In addition, a finite-impulse response (FIR) filter is designed for the multi-bit high-pass modulation path to reduce the quantization noise, while offering a time-interleaving operation to minimize the DCO sensitivity to the coupling during switching time. A two-point modulator based on a semidigital fractional-N phase-locked loop (PLL) is implemented in 0.18μm CMOS. Simulation results show that the proposed modulator can achieve 10Mb/s GFSK/GMSK modulations with the EVM of -37dB.