Spur reduction technique for fractional-N frequency synthesizer with MASH 1-1-1-1 Sigma Delta modulator

Author

Tamilselvan, V. ; Ponnambalam, Maran ; Chandramani, Premanand V.

Author_Institution

ECE Dept., SSN Coll. Of Eng., Chennai, India

fYear

2014

fDate

3-5 April 2014

Firstpage

895

Lastpage

899

Abstract

A fourth order MASH Sigma Delta modulator based fractional-N frequency synthesizer was designed and validated as a Matlab/Simulink macro- model. Use of MASH achieves a better noise shaping for the frequencies generated by the synthesizer. With a reference frequency of 20MHz, the fractional-N frequency synthesizer achieves a synthesized frequency range of 200MHz to 220MHz with 2 MHz resolution. The macro-model has a gain margin of 6.02dB and a phase margin of 39.7°, ensuring the stability of the closed loop system with settling time of 3.32μ sec. Spurs that were introduced by the fractional feedback and reference input are removed through notch type Comb filter.

Keywords

comb filters; feedback; frequency synthesizers; notch filters; sigma-delta modulation; Matlab-Simulink macromodel; closed loop system; fourth order MASH sigma delta modulator; fractional feedback; fractional-N frequency synthesizer; frequency 2 MHz; frequency 20 MHz; frequency 200 MHz to 220 MHz; gain 6.02 dB; noise shaping; notch type Comb filter; reference input; spur reduction technique; time 3.32 mus; Detectors; Frequency modulation; Lead; Noise; Phase frequency detector; Quantization (signal); Time-frequency analysis; Comb filter; MASH sigma delta modulator; Spurs; fractional-N frequency synthesizer;

fLanguage

English

Publisher

ieee

Conference_Titel

Communications and Signal Processing (ICCSP), 2014 International Conference on

Conference_Location

Melmaruvathur

Print_ISBN

978-1-4799-3357-0

Type

conf

DOI

10.1109/ICCSP.2014.6949973

Filename

6949973