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Method for Input/Output Simultaneous Switching Noise Estimation

IP.com Disclosure Number: IPCOM000117938D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Chu, AM: AUTHOR [+3]

Abstract

In a circuit having a plurality of Off Chip Drivers (OCDs), a method for determining the noise voltage, in a period of time during which some OCDs switch and others do not switch, on the output of non-switching OCDs, such OCDs each providing, on an output signal line, a signal having a nominal di/dt for a given input di/dt, and having a characteristic variation in output di/dt with respect to input bias voltage (Slope), comprising the steps of:

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Method for Input/Output Simultaneous Switching Noise Estimation

      In a circuit having a plurality of Off Chip Drivers (OCDs), a
method for determining the noise voltage, in a period of time during
which some OCDs switch and others do not switch, on the output of
non-switching OCDs, such OCDs each providing, on an output signal
line, a signal having a nominal di/dt for a given input di/dt, and
having a characteristic variation in output di/dt with respect to
input bias voltage (Slope), comprising the steps of:

      Step 1 - from the nominal output di/dt and Slope values for
each OCD, using a first novel formula to calculate a first adjusted
output di/dt for each OCD, adjusted for power bus noise effects from
the switching of all OCDs that can switch simultaneously therewith;

      Step 2 - characterizing the inductance of the signal lines of
the OCDs that are switching during said period as a set of
self-inductances and a set of mutual inductances coupling said
self-inductances, and from said first adjusted output di/dt, using a
second novel formula that utilizes said characterized inductances to
calculate a second adjusted output di/dt, adjusted for the effect of
said inductances;

      Step 3 - from said second adjusted output di/dt, using the
known M di/dt formula, calculating a first peak noise voltage
component, induced by signal line coupling, on the signal lines of
OCDs that are not switching during said period;

      Step 4 - from said se...