[SI-LIST] 回复： AW: ??: AW: ??: Re: ??: Re: How to measure the actual impedance of a stripline with DSA8200(TDR)

  • From: John Lee <venussoso@xxxxxxxx>
  • To: steve weir <weirsi@xxxxxxxxxx>, GertHavermann <Gert.Havermann@xxxxxxxxxxx>
  • Date: Thu, 13 Jan 2011 22:59:43 +0800 (CST)

Yes, Gert, thanks,
I will do it follow your suggestion.
Best Regards!
John Lee

--- 11å¹´1æ??13æ?¥ï¼?å?¨å??, Havermann, Gert <Gert.Havermann@xxxxxxxxxxx> 
å??é??ï¼?


å??件人: Havermann, Gert <Gert.Havermann@xxxxxxxxxxx>
主�: [SI-LIST] AW: ??: AW: ??: Re: ??: Re: How to measure the actual 
impedance of a stripline with DSA8200(TDR)
�件人: "John Lee" <venussoso@xxxxxxxx>, "steve weir" <weirsi@xxxxxxxxxx>
æ??é??: "SI LIST" <si-list@xxxxxxxxxxxxx>
æ?¥æ??: 2011å¹´1æ??13æ?¥,å?¨å??,ä¸?å??10:40





Hi John,

without a Plane at L5, you will have a higher impedance for your trace (60Ohm 
sounds reasonable). you can crosscheck with Polar when you simulate the trace 
using L6, 7 or 8 as the next reference plane.

BR
Gert

--------------------------------------------------------------------------
Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft: 
Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596; persönlich 
haftende Gesellschafterin: HARTING Electronics Management GmbH; Sitz der 
Komplementär-GmbH: Espelkamp; Registergericht der Komplementär-GmbH: Bad 
Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB 8808; Geschäftsführer: 
Edgar-Peter Duening, Torsten Ratzmann, Dr. Alexander Rost
________________________________


Von: John Lee [mailto:venussoso@xxxxxxxx] 
Gesendet: Donnerstag, 13. Januar 2011 15:32
An: steve weir; Havermann, Gert
Cc: SI LIST
Betreff: ??: AW: [SI-LIST] ??: Re: ??: Re: How to measure the actual impedance 
of a stripline with DSA8200(TDR)


Hi, Gert,
I have just noticed that there is not L5(Vss) in my test coupon...Maybe it's 
important, you think?

Best Regards!
John Lee

--- 11å¹´1æ??13æ?¥ï¼?å?¨å??, Havermann, Gert <Gert.Havermann@xxxxxxxxxxx> 
å??é??ï¼?



    å??件人: Havermann, Gert <Gert.Havermann@xxxxxxxxxxx>
    主�: AW: [SI-LIST] ??: Re: ??: Re: How to measure the actual 
impedance of a stripline with DSA8200(TDR)
    �件人: "John Lee" <venussoso@xxxxxxxx>, "steve weir" 
<weirsi@xxxxxxxxxx>
    æ??é??: "SI LIST" <si-list@xxxxxxxxxxxxx>
    æ?¥æ??: 2011å¹´1æ??13æ?¥,å?¨å??,ä¸?å??6:18
    
    



    Hi John,
    
    How is Vdd and Vss connected on your Test coupon? To match the Polar 
results, both have to be connected to give a clean GND return path.
    
    BR
    Gert 
    
    PS I hope this comes out right, from my previous mail the system cut off 
the first 3 lines of text.
    
    
    
--------------------------------------------------------------------------
    Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft: 
Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596; persönlich 
haftende Gesellschafterin: HARTING Electronics Management GmbH; Sitz der 
Komplementär-GmbH: Espelkamp; Registergericht der Komplementär-GmbH: Bad 
Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB 8808; Geschäftsführer: 
Edgar-Peter Duening, Torsten Ratzmann, Dr. Alexander Rost
    -----Ursprüngliche Nachricht-----
    
    Von: si-list-bounce@xxxxxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=si-list-bounce@xxxxxxxxxxxxx>  
[mailto:si-list-bounce@xxxxxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=si-list-bounce@xxxxxxxxxxxxx> ] 
Im Auftrag von John Lee
    Gesendet: Donnerstag, 13. Januar 2011 11:03
    An: steve weir
    Cc: SI LIST
    Betreff: [SI-LIST] ??: Re: ??: Re: How to measure the actual impedance 
of a stripline with DSA8200(TDR)
    
    Hi, Steve, thanks again.
    The stack-up is showed below, trace width is about 4mil.
    Besides, the signal lines in L4 maybe is not sufficient to make it as a 
reference plane.
    
    >     > L1 signal        ----
    4mil
    >     > L2 Vdd        -----------
    5mil
    >     > L3 signal        ----        target layer
    4mil
    >     > L4 signal        ----
    5mil
    >     > L5 Vss       ------------
    5mil
    >     > L6~L10     symmetry
    Best Regards!
    John Lee
    
    --- 11å¹´1æ??13æ?¥ï¼?å?¨å??, steve weir <weirsi@xxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=weirsi@xxxxxxxxxx> > å??é??ï¼?
    
    
    å??件人: steve weir <weirsi@xxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=weirsi@xxxxxxxxxx> >
    主é¢?: [SI-LIST] Re: å??å¤?ï¼? Re: How to measure the actual impedance 
of a stripline with DSA8200(TDR)
    �件人: "John Lee" <venussoso@xxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=venussoso@xxxxxxxx> >
    æ??é??: "SI LIST" <si-list@xxxxxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=si-list@xxxxxxxxxxxxx> >
    æ?¥æ??: 2011å¹´1æ??13æ?¥,å?¨å??,ä¸?å??5:09
    
    
    John, no don't add one.  Having one might have accounted for the error. 
    
    Your test coupon should look like the rest of your PCB.  Where you have 
solid planes in the PCB they should exist in the coupon.
    
    How dense is the copper on L4 in the vicinity of the signal that is 
giving you trouble?  What are your dielectric thicknesses, and trace widths?
    
    Steve.
    
    John Lee wrote:
    > Hi, steve,
    > Thank you very much.
    > Yes, i used the TDR.
    > I did not add a 50ohm terminator in series manually,  from the 
    > datasheet, i have found that the transmit cable itself already has 
    > 50ohm impedance, did i need to do so? And when i test the coupon in 
    > L3, the result is about 60ohm.
    > Is there any chance that the result is effected by L5?
    >
    > Best Regards!
    > John Lee
    >
    > --- *11å¹´1æ??13æ?¥ï¼?å?¨å??, steve weir /<weirsi@xxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=weirsi@xxxxxxxxxx> >/* å??é??ï¼?
    >
    >
    >     å??件人: steve weir <weirsi@xxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=weirsi@xxxxxxxxxx> >
    >     主�: [SI-LIST] Re: How to measure the actual impedance of a
    >     stripline with DSA8200(TDR)
    >     �件人: "John Lee" <venussoso@xxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=venussoso@xxxxxxxx> >
    >     æ??é??: "SI LIST" <si-list@xxxxxxxxxxxxx 
<http://cn.mc924.mail.yahoo.com/mc/compose?to=si-list@xxxxxxxxxxxxx> >
    >     æ?¥æ??: 2011å¹´1æ??13æ?¥,å?¨å??,ä¸?å??3:59
    >
    >     How are you measuring?  Are you using a TDR?  If so, did you 
by 
    >any
    >     chance stick a 50 Ohm terminator in series with the transmit 
cable
    >     did you?
    >
    >
    >
    >     Steve
    >     John Lee wrote:
    >     > Hi, SI experts,
    >     > I have a question about impedance measurement for DDR3 
register
    >     memory.
    >     > I have a register memory that uses 10layers stack-up as 
follows:
    >     > L1 signal        ----
    >     > L2 Vdd        -----------
    >     > L3 signal        ----        target layer
    >     > L4 signal        ----
    >     > L5 Vss       ------------
    >     > L6~L10     symmetry
    >     >
    >     > Now I want to measure the impedance of L3's signal, so i got 
a
    >     PCB (without any resisters, or DRAMs) to do the test, but no
    >     matter Vdd or Vss I choose for the reference plane, the result 
is
    >     only about a half of theoretical value (for instance, the
    >     theoretical value is 60ohm, but the measurement result is more 
or
    >     less 28ohm).
    >     >
    >     > Is there anything i missed during the measurement? And how to
    >     get the actual impedance in this situation?
    >     >
    >     > Any reply will be appreciated, thanks in advance.
    >     > Best Regards!
    >     > John Lee
    >     >
    >     >
    >     >
    >     > 
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    >     --
    >     Steve Weir
    >     IPBLOX, LLC
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