in the Design Supercon95 Proceedings
Mr. Michael A. Baxter, B.S.E.E.
Dr. Edward P. Sayre, P.E.
This paper describes the design, simulation and
characterization of a backplane system utilizing QuickRing®, a
high speed point-to-point data transfer architecture from Apple Computer.
The controllers used to implement the QuickRing architecture use National
Semiconductor's Low Voltage Differential Signaling (LVDS) CMOS technology.
This technology provides for very high-speed, low voltage swing
differential signals which minimize common mode noise interference. Each
QuickRing Data Stream Controller is capable of moving high bandwidth data
streams of up to 350M Samples/sec per line. This kind of performance
provides very high bandwidth systems with peak theoretical rates of
1.7Gbytes/sec for a 16 node ring, according to National Semiconductor.
North East Systems Associates, Inc. (NESA, Inc.), Stow MA,
has recently completed a design, simulation, and measurement program for a
QuickRing test bed (including backplane, test cards, and connectors). The
object was to produce a characterized backplane simulation which could be
used during the detailed system design program. NESA's main focus was to
verify the Signal Integrity performance of the "Ring Interface"
of the QuickRing interconnects. NESA also designed a backplane test case
which implemented realistic "rings" using QuickRing Controllers
in various configurations. Specially designed measurement ports were
integrated into the design to permit full bandwidth 350 MB/s measurements
of the ring signals. Measurements were conducted using NESA, Inc.'s Scope54TM
software and the Hewlett-Packard 54120 TDR/Digital Sampling Oscilloscope
The QuickRing backplane SPICE models, developed early in the design
cycle for performance predictions, were correlated with the Scope54
measurement data collected on the test articles. Correlation was achieved
by the on-screen overlaying of the SPICE simulation results with measured
backplane TDR's and QuickRing signals. Via this closed loop analysis, the
simulation models were easily refined to closely approximate the measured
results. The final result was a set of validated SPICE models which can be
used in predicting performance of future QuickRing designs with a high
degree of confidence and without the delays associated with re-design and
fabrication of a new set of physical test articles.
This work expands on NESA, Inc.'s characterization of the QuickRing
BASICS Connector System for Beta Phase, Inc. A similar process was employed
in this work to develop accurate characterized SPICE models suitable for
signals with risetimes as little as 200 ps.
Scope54TM is a trademark of North East Systems
QuickRing® is a registered trademark of Apple Computer,
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