[SI-LIST] Re: Does the signal reference to the vddq will increase the power plane noise?
- From: steve weir <weirsi@xxxxxxxxxx>
- To: Ravinder.Ajmani@xxxxxxxx
- Date: Tue, 25 Sep 2012 11:22:06 -0700
In differential signaling, the effects are identical with one
exception: The receiving amplifier sees the net disturbances introduced
as common mode noise. The CMR, and CMRR of the receiving amplifier then
determine the impact.
Steve.
On 9/25/2012 11:15 AM, Ravinder.Ajmani@xxxxxxxx wrote:
>
> Hi Steve,
>
> How does this affect differential signalling. In one of our designs,
> DQS and Clock are referenced to 1.8 V plane on the substrate, whereas
> on the PCB they are referencing Ground plane.
>
> Thanks.
>
>
> Regards
> Ravinder Ajmani
> HGST, a Western Digital company
> ravinder.ajmani@xxxxxxxx
>
> HGST, a Western Digital company 5601 Great Oaks Pkwy.
> San Jose, CA 95119-1003_
> __www.hgst.com_ <http://www.hgst.com/>
>
>
>
>
>
> *steve weir <weirsi@xxxxxxxxxx>*
> Sent by: si-list-bounce@xxxxxxxxxxxxx
>
> 09/25/2012 03:40 AM
> Please respond to
> weirsi@xxxxxxxxxx
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>
>
> To
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> cc
>
> Subject
> [SI-LIST] Re: Does the signal reference to the vddq will increase the
> power plane noise?
>
>
>
>
>
>
>
>
>
> To answer your question, you have to know what the signal reference is
> where it is launched, and what the receiver references where the signal
> is sensed. If a signal is launched referenced to Vss, then
> rereferencing it to something else like Vddq does three things:
>
> 1) Injects signal current into the Vddq / Vss network.
> 2) Inserts the local impedance of the Vddq / Vss network at the
> transition between references into the channel impedance.
> 3) Couples the difference voltage that is between Vddq and Vss at the
> receiver to the signal potential that the receiver sees.
>
>
> Steve.
> On 9/25/2012 1:07 AM, liewluping@xxxxxxxxxxxx wrote:
> > Hi all: this question maybe too simple but confuse me
> many weeks: if the signal reference to the io power plane,for example
> ,ddr3@1866mbps,do the power noise will increase compare to the gnd
> refernce only design which only contains ssn noise? Or what will
> happened if we measured at the boards,or the die? Does the transition
> energy couple to the vddq plane will change the result or not? thanks
> a lot. liu luping
> >
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> --
> Steve Weir
> IPBLOX, LLC
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--
Steve Weir
IPBLOX, LLC
150 N. Center St. #211
Reno, NV 89501
www.ipblox.com
(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax
All contents Copyright (c)2012 IPBLOX, LLC. All Rights Reserved.
This e-mail may contain confidential material.
If you are not the intended recipient, please destroy all records
and notify the sender.
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