Browse Prior Art Database

Time Domain Response Analysis of the RISC/6000 CPU Planar and IMC Module

IP.com Disclosure Number: IPCOM000111588D
Original Publication Date: 1994-Mar-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Corley, R: AUTHOR [+2]

Abstract

Disclosed is an application of time domain reflectometry (TDR) to measure high frequency reactance, which includes a specially constructed low inductance probe, impedance matched to a 50-ohm transmission line, a fabrication technique to eliminate need to attach ground pin to outer shield of coax, and use of superposition to subtract out probe impedance.

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Time Domain Response Analysis of the RISC/6000 CPU Planar and IMC
Module

      Disclosed is an application of time domain reflectometry (TDR)
to measure high frequency reactance, which includes a specially
constructed low inductance probe, impedance matched to a 50-ohm
transmission line, a fabrication technique to eliminate need to
attach ground pin to outer shield of coax, and use of superposition
to subtract out probe impedance.

      As clock speeds increase, parasitic capacitances and
inductances become more important as part of the overall circuit.  To
simulate a high frequency environment, implementation was made of a
time domain reflectometer to inject a fast transient pulse in the
module and planar system of the RISC/6000* CPU card.  By
approximating the reflected response of the network to an exponential
curve, determination was made of a first-order transmission line
model for the socket, Interstitial-Pin-Metallized-Ceramic (IMC)
module, pins, and planar.  Since the pulse was injected at only one
point on the module (or planar), no mutual inductance or capacitance
could be measured (loop inductance and capacitance only).

      It was discovered that the bandwidth of the probe provided in
the TDR kit was too low for experimentation; therefore, a probe was
constructed from a stainless steel SMA connector soldered onto a
piece of 50-ohm rigid coax.  At the end of the coax, an extra point
was soldered onto the outer shield as the ground tip of the pr...