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Measurements >> Phase Noise and Jitter Measurements >> noise sensitivity
https://designers-guide.org/forum/YaBB.pl?num=1173855966

Message started by sivacharan on Mar 14^th, 2007, 12:06am

Title: noise sensitivity
Post by sivacharan on Mar 14^th, 2007, 12:06am

Hi

What is the meant by noise sensitivity of a PLL??
When i saw the specifications of a PLL, it is stated that
"Noise sensitivity of this PLL is XX Ps/mV." What does it mean??

Thanks.

Title: Re: noise sensitivity
Post by mg777 on Mar 16^th, 2007, 8:35am

[Edited from original post]

The 'ps' part is the r.m.s time jitter. The 'mV' sounds like the r.m.s noise voltage at the VCO input, but over what bandwidth? My gut feeling is to take this noise bandwidth to be equal to the bandpass jitter bandwidth of the PLL.

For a first order loop i.e; loop filter H(s)=1, the quantity of interest works out to 1/K_pω_c. For a f_c=1 GHz and Kp=0.5 rad/V, the jitter per unit voltage works out to 0.3 ps/mV.

The number is O(mrad/mV) because K_p is typically O(Volt/rad).

M.G.Rajan
www.eecalc.com