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Delta Sigma Fractional-N Synthesizer

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iemotions

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fractional n synth

Does anyone have lectures about the operational

concepts about Delta Sigma Modulator used in F-N Syn.

What I get after consulting Master Google is so

tough that my stupid mind can't realize how Delta-Sigma

mechanism can move the spur noise to high frequency

and lower the spur noise power

by stupid newfresh man
 

sigma-delta n divider noise transfer function

There is a slides fyi.

Regards,

-nathanee
 

delta-sigma fractional-n synthesizers

This is a lecture from KU leuven.
 
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    akhelo

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delta sigma fractional-n synthesizer

Try this...
 

fractional-n synthesizer

The basic function of sigma delta modulator is to feedback the noise and from the output to the input this will make the noise higher but it is pushed outside of the signal bandwidth. This will reduce the noise in the signal!!
 

fractional n synthesizer

dose someone have some paper about mash sigma delta ?can give me a clear conception about that
 

delta-sigma fractional-n synthesizer

I think this is good:
"Sigma-Delta
Fractional-N Frequency Synthesis"
Scott Meninger
Michael Perrott
Massachusetts Institute of Technology
 

thanks for nathanee! Do you have any further documents about fractional frequency synthesizer?
 

"how Delta-Sigma mechanism can move the spur noise to high frequency and lower the spur noise power "

To iemotions
The Delta-Sigma modulator has the transfer function as below:
Y(z)=X(z)-N(z)*(1-z^-1)^n
for noise N(z), it is high pass
for signal X(z), it is all pass
The qutization noise from Divider of the fractional N PLL is high passed by delta sigma modulator.
so the low frequency spurs noise is supressed and moved to high frequency.
 
are there some introduction papers on the fractional N synthesizer?
 

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