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Measurements >> Phase Noise and Jitter Measurements >> noise simulation of a pulse swallow divder
https://designers-guide.org/forum/YaBB.pl?num=1213022420

Message started by claudette on Jun 9^th, 2008, 7:40am

Title: noise simulation of a pulse swallow divder
Post by claudette on Jun 9^th, 2008, 7:40am

I m trying to find out the noise contribution of the pulse swallow diver in a pll. As the division ratio is very high (10000), it is very difficult to simulate the noise using pss+pnoise. Is there a way to simulate the noise efficiently?

thanks
claudette

Title: Re: noise simulation of a pulse swallow divder
Post by Frank Wiedmann on Jun 9^th, 2008, 11:33pm

Can you reduce the division ratio without changing the signal path? I would assume that this would not change the timing jitter produced by the divider.

Title: Re: noise simulation of a pulse swallow divder
Post by claudette on Jun 11^th, 2008, 1:21am

Hi Frank, thanks for the reply.
If I reduece the division ratio, I would also decrease the noise sampling frequency. After all I get different strobed phase noise. Can I mutlipy the noise by the factor I reduce the ratio, and say this is the phase noise I should get at a high division ratio?

Title: Re: noise simulation of a pulse swallow divder
Post by Frank Wiedmann on Jun 11^th, 2008, 2:04am

If the timing jitter produced by your divider does not depend on the division ratio (you should of course verify if this is true for your circuit), the phase noise at the output will decrease when the division ratio is increased (same timing jitter/increased period duration).