Browse Prior Art Database

Noise Control

IP.com Disclosure Number: IPCOM000099435D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Chan III, F: AUTHOR [+3]

Abstract

When semiconductor chips are tested there is a large inductance between the tester power supplies and the chip, causing large on-chip delta I noise. To reduce delta I noise during testing the chip output drivers are disabled during changes to the input patterns. When the chip finishes switching to the new state, its output drivers are enabled.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 75% of the total text.

Noise Control

       When semiconductor chips are tested there is a large
inductance between the tester power supplies and the chip, causing
large on-chip delta I noise.  To reduce delta I noise during testing
the chip output drivers are disabled during changes to the input
patterns.  When the chip finishes switching to the new state, its
output drivers are enabled.

      Each driver has built-in circuitry that turns off the output
stage of the driver when a high level is received from the
chip-in-place bias line (output of blocks 1 through 12).  When a low
level is received from the chip-in-place bias line the driver
functions normally.  Receivers (blocks 27, 28), level shifters (block
25), and associated logic (blocks 18, 24, 26) are provided for
controlling the chip-in- place generators (blocks 1-12).

      An exemplary chip (not shown) has six columns of drivers, each
column has a separate chip-in-place bias line which is fed by a pair
of chip-in-place generators (i.e., blocks 1 and 2, 3 and 4, ...).  If
one generator fails the second generator provides redundancy.  The
signal from off chip that disables/enables the drivers is staggered.
Two internal delay blocks are used for each stage of delay (i.e.,
blocks 19 and 13, 20 and 14, ...).  Column 2 is delayed (see blocks
19 and 13), column 3 is delayed (see figure blocks 20 and 14), ....
Staggering the driver turn-ons reduces delta I noise.

      The chip-in-place input from off chip is terminat...