Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
1999-10-14
2001-03-27
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S705000, C324S723000, C327S066000
Reexamination Certificate
active
06208152
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a redundant resistor matching detector with constant percentage threshold.
DESCRIPTION OF THE RELATED ART
A problem exists where a redundant resistor is needed to reference the accuracy of a functional resistor to within a fixed percentage of the redundant resistor. A redundant resistor is needed was needed since a digital potentiometer implementation for the resistor had several failure mechanisms that needed to be detected.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide an improved redundant resistor matching detector. Other objects of the invention are to provide such redundant resistor matching detector with constant percentage threshold; to provide such redundant resistor matching detector with constant percentage threshold substantially without negative effect and that overcome many of the disadvantages of prior art arrangements.
In brief, a redundant resistor matching detector is provided. The redundant resistor matching detector includes a voltage reference and a first operational amplifier, a second operational amplifier, a first potentiometer and a reference potentiometer. The first operational amplifier has a first input connected to a first potentiometer. The second operational amplifier has a first input connected to the reference potentiometer. The first operational amplifier and the second operational amplifier have a reference input coupled to the voltage reference. An input current mirror is coupled to the first potentiometer providing a first current. A first reference current mirror is coupled to the reference potentiometer providing a reference current. A second reference current mirror has an input coupled to a first output of the first reference current mirror and has a first output coupled to an output of the input current mirror. A pair of series connected resistors are connected between a second output of both the first reference current mirror and the second reference current mirror. A resistor is connected between a junction of the pair of series connected resistors and the first output of the input current mirror and the first output of the second reference current mirror.
REFERENCES:
patent: 3990019 (1976-11-01), Crockett et al.
patent: 4922131 (1990-05-01), Anderson et al.
patent: 5483190 (1996-01-01), McGivern
patent: 5596268 (1997-01-01), Strong et al.
patent: 5936970 (1999-08-01), Lee
Baumgartner Steven John
Demsky Kevin Paul
Thatcher Raymond Jonathan
Hamdan Wasseem H.
International Business Machines - Corporation
Metjahic Safet
Pennington Joan
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