Nanoseconds per foot (RE: RIP: Betty Holberton)

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(a)aol.com To: classiccmp(a)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