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Unintrusive Probe Method and Hardware

IP.com Disclosure Number: IPCOM000013317D
Original Publication Date: 2000-Jul-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 6 page(s) / 36K

Publishing Venue

IBM

Abstract

Abstract All Personal Computer (PC) and Server manufacturer's developmental units utilize test equipment to validate their designs and Oscilloscopes are one of the more important tools needed. However, the four channel Agilent Technologies Infinum Oscilloscope has a very specific shortcoming. The probe design requires manual placement and when four channels are utilized, placement by hand is impossible. The most common solution is to solder gold connectors or wires to the Device Under Test (DUT) . Other solutions involve duct tape and rubber bands. This presents multiple problems: Waveform misrepresentation, extended time consumption, and inconsistent measurements. The correct solution is to construct a base to hold the DUT and a multi-jointed probe holder that allows direct probing while freeing up the Technicians/Engineers hands to perform other necessary measurement tasks. Introduction Utilizing the Agilent Technologies Infinium Oscilloscope on computer busses requires adroit technical and mechanical dexterity. A full understanding of external circuit loading along with the ability to maintain positive contact with the DUT ensures accurate measurements. The majority of bus protocols require qualifying signal measurement to verify the signal under test is a valid signal. These measurements can require

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Unintrusive Probe Method and Hardware

Abstract

All Personal Computer (PC) and Server manufacturer's
developmental units utilize test equipment to validate
their designs and Oscilloscopes are one of the more
important tools needed. However, the four channel Agilent
Technologies Infinum Oscilloscope has a very specific
shortcoming. The probe design requires manual placement
and when four channels are utilized, placement by hand is
impossible. The most common solution is to solder gold
connectors or wires to the Device Under Test (DUT). Other
solutions involve duct tape and rubber bands. This
presents multiple problems: Waveform misrepresentation,
extended time consumption, and inconsistent measurements.
The correct solution is to construct a base to hold the
DUT and a multi-jointed probe holder that allows direct
probing while freeing up the Technicians/Engineers hands
to perform other necessary measurement tasks.

Introduction

     Utilizing the Agilent Technologies Infinium
Oscilloscope on computer busses requires adroit technical
and mechanical dexterity. A full understanding of
external circuit loading along with the ability to
maintain positive contact with the DUT ensures accurate
measurements. The majority of bus protocols require
qualifying signal measurement to verify the signal under
test is a valid signal. These measurements can require

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four channels or more. The existing probe design requires
manual placement, limiting the number of probes to two.
This document will outline a solution to use multiple
probes simultaneously to take measurements on a DUT.

What is Signal Quality Analysis

     Signal Quality Analysis (SQA) is a method used to
verify signal integrity against industry specifications in
order to ensure the production of properly functioning
devices that integrate seamlessly with other devices. If
SQA is not performed, these devices could prove
non-compliant with current specifications and be
incompatible with other devices. Utilizing the AGILENT
oscilloscope, a variety of parameters, (Rise Time, Fall
Time, Overshoot, Undershoot, Noise, and Slope Reversal)
are measured against the vendor's specifications. Special
attention is paid to the functionality of a DUT and its
cooperative relationship with particular planars.

AGILENT Infinium Oscilloscope

     The AGILENT Infinium oscilloscope is a 4 GHz, 4
channel digital test device that is used to measure
waveforms and is a requirement to perform SQA. It is a
powerful tool that allows exacting measurements on the
ever-increasing speeds of computer buses.

Need for Multiple Probes

     Computer bus protocols specify which signals to
measure and that certain signals must be measured

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simultaneously as qualifiers. For example: Synchronous
Dual Inline Memory Module (SDIMM) specifications require
Chip Select (/CS) to be low, Clock (/CLK) be measured on
the rising edge, and Write Enable (/WE) to be low, for a
Data line to be valid. This requires all four channels to
be connected to the DUT. Other interface buses ca...