[SI-LIST] Re: Query on power noise sensitivity measurement problem

 Depending on the IP you will more than likely be able to put your Serdes in 
repeater mode which will allow you to test your  PLL sensitivity to both input 
jitter and power supply variation.  If you are unable to get your device in 
repeater mode you should be able to get some sort of compliance pattern out of 
your device on the TX pins which will allow you to test the power supply 
variation.  
Make sure that you AC couple your SJ source on your power supply and sweep 
across the frequency of interest while measuring your output TX response.  If 
you are able try and get your TX probes right across the output terminals into 
a compliance load (100ohm/.01UF cap).  





-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of Huang chunxing
Sent: Saturday, April 26, 2008 2:02 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Query on power noise sensitivity measurement problem

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Hi experts,

I am trying to find out whether it is possible to get the relationship =
between powernoise and output jitter by measurement.
To be convenient, I would like to call it Power Noise sensivity. =20

My initial thought is to inject a certain frequency power noise on PLL =
power, and then measure SJ at the frequency on TX output signal.=20
But it is some difficult to be applied in practice due to PDN impedance =
variance.
Is there any craft method to avoid it?

As to RX side, it is difficult to loop out clock recovered by CDR.
I was ever been told that as TX and RX share same PLL, or use same =
design PLL, so power sensitivity at RX is similar with power sensitivity =
at TX. If we measure power sensitivity at TX, then we can get one at RX.
Is that true, or could stand at most cases?

I tried to find some documents for reference, but I failed.
I hope experts here who ever did similar work may give me some comments =
and suggestions.
Thanks in advance! =20


Regards,

Huang Chunxing
HUAWEI TECHNOLOGIES CO.,LTD. =20


Address: Huawei Industrial Base
Bantian Longgang
Shenzhen 518129, P.R.China
Tel: +86 755 89651027
Fax: +86 755 89650600
E-mail: huangchunxing@xxxxxxxxxx
www.huawei.com



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