[SI-LIST] Re: Trace impedance

Actually Doug unless Polars Si6000 impedance calculator is wrong the 
answer is yes.
trace width 11.97/12.97 mils, separation 5.323 mils, 1.2 mil thick, 16 
mils above plane, Er 4.2
Differential impedance 100 ohms, Z odd 50, Z even 99.99 Zcommon 50
I've attached a jpeg screenshot,  which the list will strip off, but you 
should get it.
Dave Instone
Oxford Semiconductor Ltd
25 Milton Park
Abingdon
Oxon ox14 4sh
UK
www.oxsemi.com
+44 (0)1235 824963



Doug Brooks wrote:
> Actually, the answer is no.
>
> Zdiff = 2*Zo(1 - k)
> Zcommon = .5 * Zo(1 + k)
>
> where k is a factor related to the coupling between the traces (and 
> whose limits are between 0 and 1.0).
>
> Single-ended impedance and common mode impedance of a differential 
> pair have different meanings.
>
> Doug Brooks
>
>
>
>
> At 06:48 AM 11/21/2006, you wrote:
>   
>> Hello All,
>>                    One basic question on differential pair trace 
>> impedance. Is it possible that a differential pair with 100 ohm 
>> differential impedance will have 50 ohm common mode impedance? Are 
>> the single-ended and common mode impedances of a differential pair 
>> has the same meaning?
>> Thanks and advance,
>> shekh
>>
>>
>>
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>
> ____________________________________________________________________________-
> Check out UltraCAD's differential impedance and skin effect 
> calculators at http://www.ultracad.com 
>
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-- Binary/unsupported file stripped by Ecartis --
-- Type: image/jpeg
-- File: common.jpg


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