RE: [IBIS] [IBIS-Users] How to describe the differential pair in EBD?

Dear Young-Seok Hong,

I am no expert, but as it appears that you haven't received a response to your
question yet, I'll try to answer it for you.

As you noticed, the Electrical Board Description format does not support
'loops'.  If the loop contains a passive component, then the loop may be
"broken" (effectively removed) by replacing the passive component with a
reference to an IBIS model of the passive component.  (The loop is broken
because the path description itself or a fork within the path description will
end at the reference to the IBIS model.)

Also, the Electrical Board Description format considers all lumped capacitance
to be a description of a capacitor to ground.

So, in your specific example, you must replace C1 with an IBIS model of a
capacitor.  You could also replace R1 with an IBIS model of a resistor, but
that is optional.  If you just replace the capacitor with an IBIS model of the
capacitor, then your path description would look like:


Pin 1 -----Length a -----R1.1 -----Length b -----Node C1.1 -----Length c -----Node U1.1

                          |

Pin 2 -----Length d -----R1.2 -----Length e -----Node C1.2 -----Length f -----Node U1.2

     

  [Path Description]

  Pin1

  Len a /

    Fork

    Len b /

    Node C1.1

    Len c /

    Node U1.1

    Endfork

  len R1 /

    Fork

    Len e /

    Node C1.2

    Len f /

    Node U1.2

    Endfork

  Len d /

  Pin 2


If your were to also replace R1 with an IBIS model of the resistor, then you
would end up with two completely separate path descriptions, one for external
pin 1 and another for external pin 2.

Best regards,
Matthew Flora


________________________________

	From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of YoungSeok Hong
	Sent: Monday, March 07, 2005 4:15 PM
	Cc: ibis; ibis-users@eda.org ; owner-ibis-users@eda.org 
	Subject: [IBIS] [IBIS-Users] How to describe the differential pair in EBD?
	
	

	Hi, experts! 

	 

	I'm trying to make an EBD model. But I have a problem with the differential pair description.

	Let us suppose that the diff. pair is like follwoing (there is a loop)

	Can anyone let me know how to  describe ?

	 

	Thanks.

	Young-Seok

	 

	Pin 1 -----Length a -----------Node R1.1-----------Length b---------Length C1.1------------Node 1

	                                                     |                                                           |

	Pin 2 -----Length c -----------Node R1.2-----------Length d---------Length C1.2------------Node 2

	 

	[Path Description]

	Pin1

	Len a /

	  Fork

	  Node R1.1

	  Node R1.2

	    Fork

	    Len c /

	    Pin 2

	    Endfork

	  Len d /

	  ???

	 

	================================== 

	Young-Seok Hong 

	Memory Division 

	Device Solution Network 

	SAMSUNG ELECTRONICS CO., LTD. 

	E-mail : youngs.hong@samsung.com 

	================================== 

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