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# Resistor Model with Feedback to Control Voltage or Current in Simulation

IP.com Disclosure Number: IPCOM000115712D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 54K

IBM

Tarn, C: AUTHOR

## Abstract

Disclosed is a resistor model for use in simulation to control a node voltage or branch current. The model reduces simulation time by enabling resistor trimming in DC simulation rather than by transient analysis as was required for previous models.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

Resistor Model with Feedback to Control Voltage or Current in Simulation

Disclosed is a resistor model for use in simulation to control
a node voltage or branch current.  The model reduces simulation time
by enabling resistor trimming in DC simulation rather than by
transient analysis as was required for previous models.

In circuit design, it is often necessary to control an element
function (i.e., a branch current or node voltage) to a high degree
accuracy.  Thus, variable resistors are incorporated into a circuit
for controlling these functions which may be adjusted or "trimmed"
after completion of the manufacturing process.  Controlling resistors
in a computer simulation model of this type of circuit must be
trimmed in a similar fashion prior to simulation analysis.  The
present invention introduces a method for performing such trimming.

The proposed resistor model senses the difference between a
desired element function value and a predetermined value, adjusting
the resistor with the difference generated from the previous pass
analysis.  The resistor with the difference generated from the
previous pass analysis.  The resistor model that controls a branch
current is described as follows:
MODEL LRTRIMI (S1,S2,NC2)
EISENSE, S1-S2 = 0
PITARGET = 0
PTONOFF = 1
PTARGET = (PITARGET * PTONOFF + (1 - PTONOFF) * Isub EISENSE)
PIDIFF = (Isub EISENSE - PTARGET)
PRF = (PRF * (1 - PIDIFF/PRF))
R...