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US 6,583,374 B2Granted
Microelectromechanical system (MEMS) digital electrical isolator
AssigneeRockwell Automation Technologies, Inc.
InventorsMichael J. Knieser, Richard D. Harris, Robert J. Kretschmann, Ernst H. Dummermuth, Patrick C. Herbert
Life of this patent
Estimating the term…
Abstract
A microelectricalmechanical system (MEMS) digital isolator may be created in which an actuator such as an electrostatic motor drives a beam against a predefined force set, for example, by another electrostatic motor. When the threshold of the opposing force is overcome, motion of the beam may be sensed by a sensor also attached to the beam. The beam itself is electrically isolated between the locations of the actuator and the sensor. The structure may be incorporated into integrated circuits to provide on-chip isolation.
Claims29
A micro-electro-mechanical system (MEMS) digital isolator, comprising:
- a substrate;
- an element supported by the substrate for movement between a first and second position with respect to the substrate, where at least a portion of the element between a first and second location on the element is an electrical insulator to electrically isolate the first and second locations from each other;
- an actuator attached to the first portion of the element to receive an input electrical signal and exert a force dependent on the input electrical signal urging the element toward the second position;
- a bias structure attached to the element to exert a predetermined opposite force on the element urging the element toward the first position;
- and
- a sensor attached to the second portion of the element to provide an output electrical signal indicating movement of the element between the first position and the second position;
- whereby an input signal of above a predetermined magnitude overcomes the opposite force to cause the element to move rapidly from the first to the second position to produce the output electrical signal electrically isolated from the input electrical signal;
- wherein the sensor is selected from the group consisting of a capacitive sensor, a piezoelectric sensor, a photoelectric sensor, a resistive sensor, and an optical switching sensor.
5 more elements
An isolated circuit module comprising:
- a substrate;
- a plurality of interconnected solid state electronic devices formed on the substrate into an integrated circuit having input and output points;
- a mechanical digital isolator also formed on the substrate and electrically attached to at least one of the integrated circuit input and output points, the mechanical digital isolator including:
- (1) an element supported by the substrate for movement between a first and second position with respect to the substrate, where at least a portion of the element between a first and second location on the element is an electrical insulator to electrically isolate the first and second locations from each other;
- (2) an actuator attached to the first portion of the element to receive an input electrical signal and exert a force dependent on the input electrical signal urging the element toward the second position;
- (3) a bias structure attached to the element to exert a predetermined substantially fixed force on the element urging the element toward the first position;
- and
- (4) a sensor attached to the second portion of the element to provide an output electrical signal indicating movement of the element to the second position, the output electrical signal being electrically isolated from the input electrical signal;
- whereby an input signal of above a predetermined magnitude overcomes the fixed force to cause the element to move rapidly from the first to the second position.
6 more elements
A method of providing electrical isolation of a digital signal to a circuit employing a MEMS digital isolator of a type having:
- (i) a substrate;
- (ii) an element supported by the substrate for movement between a first and second position with respect to the substrate, where at least a portion of the element between a first and second location on the element is an electrical insulator to electrically isolate the first and second locations from each other;
- (iii) an actuator attached to the first portion of the element to receive an input electrical signal and exert a force dependent on the input electrical signal urging the element toward second position;
- (iv) a bias structure attached to the element to exert a predetermined substantially fixed force on the element urging the element toward the first position;
- and
- (v) a sensor attached to the second portion of the element to provide an output electrical signal indicating movement of the element to the second position, the output electrical signal being electrically isolated from the input electrical signal, the method comprising the steps of:
- (1) identifying a logical threshold for an input signal beyond which a logical true is indicated and beneath which a logical false is indicated;
- (2) adjusting the bias structure to exert a fixed force on the elements toward the first position sufficient so that the actuator cannot move the element toward the second position for input signals beneath the threshold;
- and
- (3) providing an output logical true signal only with movement of the element to the second position.
7 more elements
Dependencies are inferred from the claim text.