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

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From: Mark Alexander (Mark.Alexander@xilinx.com)
Date: Tue Apr 24 2001 - 13:47:12 PDT


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]
> 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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