Browse Prior Art Database

Fixture for Driver Signal Pick Up

IP.com Disclosure Number: IPCOM000105183D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Lemoine, JM: AUTHOR

Abstract

Disclosed is a fixture that allow very accurate access measurements on semiconductor devices having high impedance inputs.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 73% of the total text.

Fixture for Driver Signal Pick Up

      Disclosed is a fixture that allow very accurate access
measurements on semiconductor devices having high impedance inputs.

      In order to make accurate access measurements on high impedance
inputs the following problems have to be solved.

o   Pick-up a portion of the signal for the measurement tool (usually
    scope) without affecting the transmitted signal to the device
    under test.  Present scope probes are not suitable for accuracy
    better than 100ps.  This problem can be solved by use of a power
    divider, half of the signal going to the DUT (Device Under Test)
    the other half to the scope.  Figure 1 gives schematic of this
    circuit.

o   Prevent reflection coming from DUT high impedance input to affect
    measuring tool signal.  This problem can be solved by use of a
    second power splitter.  One output of this power splitter is
    connected to DUT the other one is connected to a short.  The
    purpose of this power split ter is to annihilate positive
    reflections coming from DUT by negative reflections coming from
    short.

      Difficulty encountered with this fixture is to get a good
annihila tion of reflected waves because the open at DUT input is not
a perfect open.  Effect of this problem can be reduced by designing a
short that is not a perfect short but his is very time consuming and
has to be done again for each new probe.

     ...