[SI-LIST] Re: help me
- From: zhangkun 29902 <zhang_kun@xxxxxxxxxx>
- To: ludwig@xxxxxxxxxxxxxxxxx
- Date: Sat, 04 Feb 2006 00:14:34 +0800
Dear Stefan
Thank you for the explaination.
Based on the situation, there is another question. How does the leakage current
affect the power integrity of the PCB and package? Now, I have not seen any
paper on this topic.
Best Regards
Zhangkun
2006.2.3
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----- Original Message -----
From: Stefan Ludwig <ludwig@xxxxxxxxxxxxxxxxx>
Date: Friday, February 3, 2006 4:46 pm
Subject: [SI-LIST] Re: help me
> Jagaveer, Zhangkun,
>
> Zhangkun is right, 3 Ohms on a board with mounted chips is not an
> issue.
> The reason is because of leakage current in transistors. As
> process
> technology progresses (180nm -> 130nm -> 90nm ...), the leakage
> current
> in a transistor gets bigger. That is, a transistor, even when it
> is
> "off", will have some current flowing through it. Also, you can
> pack
> more transistors onto a chip. Therefore, you end up with tens to
> hundreds of millions of leaky transistors, which leads to a low
> resistance when measured with an Ohm-meter.
>
> Cheers,
>
> Stefan Ludwig
>
> zhangkun 29902 wrote:
>
> >Dear jagaveer
> >
> >Do not worry about the problem. I have met this kind of problem
> for several times. When the IC is soldered on the PCB, the dc
> resistance between power and ground is very small.
> >
> >However, I am not sure the reason. The IC vendor did not explain it:(
> >
> >Best Regards
> >
> >Zhangkun
> >2006.2.3
> >
> >
> >******************************************************************************************
> > This email and its attachments contain confidential information
> from HUAWEI, which is intended only for the person or entity whose
> address is listed above. Any use of the information contained
> herein in any way (including, but not limited to, total or partial
> disclosure, reproduction, or dissemination) by persons other than
> the intended recipient(s) is prohibited. If you receive this e-
> mail in error, please notify the sender by phone or email
> immediately and delete it!
> >
> *****************************************************************************************>
> >----- Original Message -----
> >From: jagaveer25 <jagaveer25@xxxxxxxxxxx>
> >Date: Friday, February 3, 2006 12:25 pm
> >Subject: [SI-LIST] help me
> >
> >
> >
> >>Hi folks,
> >>
> >>
> >>I have done in one PCB. It is 12 layer board
> >>
> >>I have used 4 digital signal processor and one field
> programmable
> >>gate array for this pcb .
> >>
> >>Dsp side I have used 3 pwr supplies
> >>
> >>1v
> >>1.5v
> >>2.5v
> >>before I have populated that dsp I have checked between the all
> >>pwr
> >>supply and gnd resistance is very high resistance but
> >>after I have populated that 3 dsp I have checked between the
> >>1Vpwr
> >>supply and gnd resistance is only 3 ohms
> >>
> >>my 1v pwr section is 20A design
> >>
> >>I can't understand this type of problem
> >>Can u give any solution for this problem I have appreciate it
> >>
> >>Thanks
> >>V.jagaveer
> >>
> >>
> >>
> >
> >
> >
>
> --
>
> Ludwig Systems Engineering Consulting - Design -
> ImplementationWWW: www.ludwigsystems.com System
> Architectures - FPGAs - PCBs
> Ph/Fx: +41-43-355-58-73/74 Hardware - Firmware - Software
>
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