Integrated magnetic field strap for signal isolator
First Claim
1. An integrated signal isolator having first and second ends, wherein the integrated signal isolator comprises:
- first and second isolator input terminals;
first and second isolator output terminals;
first and second power supply terminals;
first, second, third, and fourth magnetoresistors, wherein the first and second magnetoresistors are coupled to the first isolator output terminal, wherein the second and third magnetoresistors are coupled to the first supply terminal, wherein the third and fourth magnetoresistors are coupled to the second isolator output terminal, and wherein the first and fourth magnetoresistors are coupled to the second supply terminal; and
, an input strap having at least one turn coupled between the first and second isolator input terminals, wherein the input strap is disposed with respect to the first, second, third, and fourth magnetoresistors so that a magnetic field is generated over two of the magnetoresistors in one direction, so that a magnetic field is generated over the other two of the magnetoresistors in an opposite direction, and so that, when input current flows between the first and second isolator input terminals, a resistance of the first magnetoresistor tracks a resistance of the third magnetoresistor, and a resistance of the second magnetoresistor tracks a resistance of the fourth magnetoresistor.
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Accused Products
Abstract
An integrated signal isolator is provided to isolate first and second circuits. First, second, third, and fourth magnetoresistors of the isolator are coupled together so as to form a Wheatstone bridge. The first second, third, and fourth magnetoresistors are arranged so that the Wheatstone bridge is immune to uniform external magnetic fields having any direction. An input strap generates magnetic fields across the first, second, third and fourth magnetoresistors in response to a signal from the first circuit so that the Wheatstone bridge provides an output to the second circuit that is commensurate with the signal from the first circuit.
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Citations
30 Claims
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1. An integrated signal isolator having first and second ends, wherein the integrated signal isolator comprises:
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first and second isolator input terminals;
first and second isolator output terminals;
first and second power supply terminals;
first, second, third, and fourth magnetoresistors, wherein the first and second magnetoresistors are coupled to the first isolator output terminal, wherein the second and third magnetoresistors are coupled to the first supply terminal, wherein the third and fourth magnetoresistors are coupled to the second isolator output terminal, and wherein the first and fourth magnetoresistors are coupled to the second supply terminal; and
,an input strap having at least one turn coupled between the first and second isolator input terminals, wherein the input strap is disposed with respect to the first, second, third, and fourth magnetoresistors so that a magnetic field is generated over two of the magnetoresistors in one direction, so that a magnetic field is generated over the other two of the magnetoresistors in an opposite direction, and so that, when input current flows between the first and second isolator input terminals, a resistance of the first magnetoresistor tracks a resistance of the third magnetoresistor, and a resistance of the second magnetoresistor tracks a resistance of the fourth magnetoresistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An integrated signal isolator having first and second ends, wherein the integrated signal isolator comprises:
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first, second, third, and fourth magnetoresistors, wherein the first and second magnetoresistors are coupled to a first isolator output terminal, wherein the second and third magnetoresistors are coupled to a first supply terminal, wherein the third and fourth magnetoresistors are coupled to a second isolator output terminal, and wherein the first and fourth magnetoresistors are coupled to a second supply terminal; and
,an input strap having at least one turn coupled between first and second isolator input terminals, wherein the least one turn has a first portion running alongside two of the magnetoresistors and a second portion running alongside the other two magnetoresistors, wherein the at least one turn is arranged so that current supplied to the input strap flows through the first portion in a first direction between the first and second ends and through the second portion in a second direction between the first and second ends, and wherein the first and second directions are substantially opposite to one another. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of isolating first and second circuits comprising:
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generating a first field across at least one magnetically responsive element, wherein the first field is generated in response to an isolator input signal from the first circuit;
generating a second field across at least another magnetically responsive element, wherein the second field is generated in response to the isolator input signal from the first circuit, and wherein the first and second fields are substantially opposite to one another in direction; and
,supplying an isolator output signal to the second circuit, wherein the isolator output signal is derived across the at least two magnetically responsive elements, and wherein the first and second fields are generated so that the isolator output signal is responsive to the isolator input signal that generates the first and second fields but not to an external field. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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26. A method of making an integrated signal isolator having first and second ends comprising:
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forming first, second, third, and fourth magnetoresistors in a first layer of an integrated structure so that the first and second magnetoresistors are substantially aligned along a first axis, so that the third and fourth magnetoresistors are substantially aligned along a second axis, and so that the first axis is offset from and parallel to the second axis;
coupling the first and second magnetoresistors to a first isolator output terminal;
coupling the second and third magnetoresistors to a first supply terminal;
coupling the third and fourth magnetoresistors to a second isolator output terminal;
coupling the first and fourth magnetoresistors to a second supply terminal;
forming an input strap in a second layer of the integrated structure so that the input strap, when receiving an input, generates a field across two of the first, second, third, and fourth magnetoresistors and an opposing field across the other two of the first, second, third, and fourth magnetoresistors; and
,coupling the input strap between first and second isolator input terminals. - View Dependent Claims (27, 28, 29, 30)
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Specification