Title :
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
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;
Conference_Titel :
Communications and Signal Processing (ICCSP), 2014 International Conference on
Conference_Location :
Melmaruvathur
Print_ISBN :
978-1-4799-3357-0
DOI :
10.1109/ICCSP.2014.6949973
