Phase noise contribution of Sigma-delta modulator

[hmsheng]

Sigma-delta modulator is often used in a fractional-N frequency synthesizer. We can analyze the preformance of the SDM with Matlab program. How can we calculate the phase noise contribution of the SDM to the output of frequency synthesizer?

 

[swicap]

phase noise from dsm is actually the dsm quantizaion noise. The quantization noise can be transformed to the pll input noise and then we can get pll output noise from dsm.

 

[hmsheng]

swicap,

Yeah. I know phase noise from SDM is caused by the quantization noise. How to transform the quantization noise to the phase noise of PLL by calculation method? Could you please say it in detail?

 

[swicap]

some papers and book give the formula.
The book: CMoS pll synthesizers: Anaylysis and Design. by Sanchez.
I can't remember paper titles.
copeland's papers maybe. you can search them in IEEE.