Re: [SI-LIST] : PCB track length and ringing

Karthik Ethirajan (KarthikE@calmicro.com)
Tue, 23 Sep 1997 12:14:07 -0700

Hi!
When you terminate a high speed bus with a termination resistance greater than
the characteristic impedance (Zo) of the bus trace, a positive reflection occurs
resulting in ringing. This type of impedance mismatch can occur due to the
presence of vias, stubs, etc. as Hans mentioned.

A good reference which explains this concept is Motorola Semiconductor App Note,
Doc. AN 1051/D, 1990.

-Karthik

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Karthikeyan Ethirajan
Applications Engineer (408) 934-3181

California Micro Devices 215 Topaz Street
karthike@calmicro.com Milpitas, CA 95035
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>>> "Gopala Krishna M.R." <gkrishna@rri.ernet.in> 09/22 8:32 PM >>>
Hi,

Can someone explain how the PCB (printed circuit board) track (signal
trace) length causes ringing in the High Speed Digital Signal systems.

Regards,
Gopalkrishna