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Can Delta-Sigma replace Accumulator in Fraction-N PLL?

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dd2001

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accumulator in pll

Can Delta-Sigma replace Accumulator in Fraction-N PLL?

IF Delta-Sigma can replace accumulator in Fraction-N PLL, how to difine input, output of sigma-delta and swallow counter input?
 

kokokiki

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It can.
The Delta-Sigma input is swallow out.
The swallow input is Delta-Sigma 1 bit out.
 

RC13

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The accummulator in the Fractional-N represent the "sigma", it is already delta-sigma.?
 

kokokiki

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No, it is not.
The accummulator is only represent the "sigma" in the Fractional-N PLL application.

The delta-sigma function can be a time * pulse density cost function.
It is also M-bit * time => N bit * time density transfer function.
The time is times in in Fraction-N PLL application.
So, The 1 bit output is index divisor.
 

kjjian

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kokokiki said:
It can.
The Delta-Sigma input is swallow out.
The swallow input is Delta-Sigma 1 bit out.
Can you explain clearly?
Many papers saidthat the The Delta-Sigma input is fractional code,and it can't be the swallow out.
 

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