why my pll's settling time is so long ?

[xihuwang]

pll settling time

Hi, everyone :
I designed a pll , to get jitter lower than 2ns , it need several hundreds us.
But I read the papers on pll , it is said that their "lock time " is several us .
So my question is , wheather "locking time" is equal to " settling time" ?

 

[xihuwang]

settling time pll

pls help !

 

[gaom9]

settling time bandwith

These times are mainly determined by the loop-bandwidth of your PLL.
Large loop-bandwidth: small settling time but large in-band noise
Small loop-bandwidth: large settling time but good in-band noise
If the loop-bandwidth is about 200KHz, the settling time is about 10us.

Best regards

 

[xiaoshao]

settling time lock time bandwidth

the loop bandwidth is too small