needforspeed
Member level 1
phase noise to jitter
hi,
I simulated my PLL's phase noise at behavior level and got a closed-loop pll phase noise curve. Than I tried to integrate the phase noise to get phase jitter and period jitter.
The following matlab routine is used to convert phase noise to phase jitter and period jitter:
phasejitter = sqrt(integral(fre,2*Lpll))*T/(2*pi);
periodjitter = sqrt(8*integral(fre,Lpll.*(sin(pi*fre*T)).^2)/((2*pi*f)^2));
where Lpll is the single-sideban phase nosie of the pll, the function integral is:
function integ = integral(fre,L)
% calculate integral
len=length(fre);
for n = 1:len-1
areatrape
= (fre(n+1)-fre)*(L(n+1)+L)/2;
end
integ = sum(areatrape);
I expect the same results of phase jitter and period jitter because the pll locked. but the results are:
phase jitter = 8.31e-11
period jitter = 3.27e-12
Is there any error of my routine or my understanding of phase jitter and period jitter?
in the attached figure, the red curve is the phase noise of the PLL.
hi,
I simulated my PLL's phase noise at behavior level and got a closed-loop pll phase noise curve. Than I tried to integrate the phase noise to get phase jitter and period jitter.
The following matlab routine is used to convert phase noise to phase jitter and period jitter:
phasejitter = sqrt(integral(fre,2*Lpll))*T/(2*pi);
periodjitter = sqrt(8*integral(fre,Lpll.*(sin(pi*fre*T)).^2)/((2*pi*f)^2));
where Lpll is the single-sideban phase nosie of the pll, the function integral is:
function integ = integral(fre,L)
% calculate integral
len=length(fre);
for n = 1:len-1
areatrape
= (fre(n+1)-fre)*(L(n+1)+L)/2;end
integ = sum(areatrape);
I expect the same results of phase jitter and period jitter because the pll locked. but the results are:
phase jitter = 8.31e-11
period jitter = 3.27e-12
Is there any error of my routine or my understanding of phase jitter and period jitter?
in the attached figure, the red curve is the phase noise of the PLL.