RE: [SI-LIST] : RE: 2.5 GHz in FR4

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From: Larry Miller (ldmiller@rhapsodynetworks.com)
Date: Tue Apr 24 2001 - 15:20:21 PDT


These are easily measured with an OMmeter. You know, the kind you hold up in
the air and go "Ommmmmm".
 
The woman who plays the nurse manager on "Becker" used to advertise for
them; if you stayed up past midnight a few years ago and watched TV you
surely caught her ads.
 
/* just kidding, folks */
 
Larry Miller

-----Original Message-----
From: Mark Alexander [mailto:Mark.Alexander@xilinx.com]
Sent: Tuesday, April 24, 2001 1:47 PM
To: Larry Miller
Cc: 'RMELLISON@aol.com'; j-gaboian@ti.com; zabinski.patrick@mayo.edu;
si-list@silab.eng.sun.com
Subject: Re: [SI-LIST] : RE: 2.5 GHz in FR4

Larry,

These 'psychic connections' of which you speak sound very interesting.
Could you elaborate?

-mark
  
  

Larry Miller wrote:

>> How do you connect a surface mount part to stripline without using vias?

Well, I don't think you can unless you are using psychic
connections.Seriously, I guess I should have been more specific. The HS-3
connectors are through-hole and the impedance characteristics include this
fact. AMP has very definite rules for routing through a pin forest, escaping
out from the connector, etc.So I guess when I say "no vias" in this context
I mean no additional vias except for the pin connection at each end. I have
done TDR measurements for this and there are small impedance bumps at the
pins, but they are very small in amplitude and short in length,
corresponding in both respects to very high frequencies above those for
which the connectors (and the system) are rated.As a matter of fact, for the
plug-in boards we had the surface mount situation: both the fiber optic
transceiver and the SERDES chip were surface mount, so we did not dive into
inner stripline layers, We stayed on the top layer and used microstrip for
this very short (1") trace length. Again, "no vias", but in this case REALLY
no vias.So you are not confused.Regards,Larry Miller

-----Original Message-----
From: RMELLISON@aol.com [ mailto:RMELLISON@aol.com
<mailto:RMELLISON@aol.com> ]
Sent: Saturday, April 21, 2001 2:46 AM
To: ldmiller@rhapsodynetworks.com; j-gaboian@ti.com;
zabinski.patrick@mayo.edu; si-list@silab.eng.sun.com
Subject: Re: [SI-LIST] : RE: 2.5 GHz in FR4
 
Larry, Im confused.
How do you connect a surface mount part to stripline without using vias?
Richard Ellison
ph. 972-569-8317

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