Nanoseconds per foot (RE: RIP: Betty Holberton)

From: Richard Erlacher <edick_at_idcomm.com>
Date: Thu Dec 13 00:22:02 2001

The work done by Blood and published in the Motorola MECL System Design Handbook is still the idustry benchmark, used by the guys who write the IBIS models and processing software.

Dick
  ----- Original Message -----
  From: CLeyson_at_aol.com
  To: classiccmp_at_classiccmp.org
  Sent: Wednesday, December 12, 2001 7:26 PM
  Subject: Re: Nanoseconds per foot (RE: RIP: Betty Holberton)


  For coax or twisted pair the delay per unit length is given by:-

  Delay (Secs/unit length) = Root( (C/unit length)*(L/unit length) )

  Example: For RG58-U coax, C=100pF/m and L=250nH/m
  Delay = root(250E-9*100E-12) = 5E-9 sec/m or 5ns/m
  A pulse will travel 66% slower in RG-58 cable than free space.

  If anyone needs to lay out high speed PCB's
  the following book is highly recommended:

  "High Speed Digital Design - A Handbook of Black Magic"
  Howard W Johnson and Martin Graham
  ISBN 0-13-395724-1

  Chris Leyson
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