Method and apparatus for in-circuit impedance measurement
First Claim
1. A device configured to measure an impedance between first and second nodes of an electrical circuit, the device comprising:
- a) at least one current source configured to provide first and second currents of known values;
b) first and second probes, connected to the at least one current source, and configured to contact the respective first and second nodes to apply the first and second currents to the first and second nodes;
c) a third common probe, connected to the at least one current source, configured to contact the circuit at a common node at a location that has an equal current flow with respect to the first and second nodes;
d) at least one voltage meter, configured to be connected to the first and second nodes, to measure voltages corresponding to the first and second currents; and
e) a processor, operatively coupled to the at least one current source and the at least one voltage meter, capable of calculating the unknown impedance based on the known values of the first and second current and the measured values of the voltages.
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Abstract
A device for measuring an impedance between first and second nodes in an electrical circuit without removing components includes at least one current source to provide first and second currents or current signals of known values. First and second probes contact the respective first and second nodes to apply the first and second currents. A third common probe contacts the circuit at a common node that experiences the same current flow as between the first and second nodes. At least one voltage meter measures voltages corresponding to the first and second currents. A processor calculates the impedance based on the known values of the currents, and the measured values of the voltages.
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Citations
58 Claims
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1. A device configured to measure an impedance between first and second nodes of an electrical circuit, the device comprising:
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a) at least one current source configured to provide first and second currents of known values;
b) first and second probes, connected to the at least one current source, and configured to contact the respective first and second nodes to apply the first and second currents to the first and second nodes;
c) a third common probe, connected to the at least one current source, configured to contact the circuit at a common node at a location that has an equal current flow with respect to the first and second nodes;
d) at least one voltage meter, configured to be connected to the first and second nodes, to measure voltages corresponding to the first and second currents; and
e) a processor, operatively coupled to the at least one current source and the at least one voltage meter, capable of calculating the unknown impedance based on the known values of the first and second current and the measured values of the voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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15. An impedance measurement device, comprising:
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a) a circuit having first and second nodes, and at least one parallel current path which experiences an equal current flow with respect to the first and second nodes;
b) first and second probes, contacting the respective first and second nodes;
c) a third common probe, contacting the circuit at a common node at a location that experiences equal current flow with respect to the first and second nodes;
d) at least one current source, connected to the at least first and second probes, configured to provide first and second currents of known values to be applied to the respective first and second nodes; and
e) at least one voltage meter, configured to be connected to the first and second nodes, to measure voltages corresponding to the first and second currents.
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29. A method for measuring an impedance between first and second nodes of an electrical circuit without removing components from the circuit, the method comprising the steps of:
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a) selecting first and second nodes within the circuit;
b) selecting a common node at a location different from the first and second nodes and that has a concurrent current flow equal in value to current flow between the first and second nodes; and
c) calculating the impedance based on known values of currents and measured values voltages.
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44. A method for measuring an impedance between first and second nodes in an electrical circuit, the method comprising the steps of:
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a) contacting the first and second nodes with first and second probes;
b) selecting a common node at a location which experiences an equal current flow with respect to the first and second nodes;
c) contacting the common node with a third probe;
d) applying a first current of known value at the first node;
e) applying a second current of known value at the second node;
f) measuring a first voltage at the first node due to the first current;
g) measuring a second voltage at the first node due to the second current source;
h) measuring a third voltage at the second node due to the second current source;
i) measuring a fourth voltage at the second node due to the first current source; and
j) calculating the impedance of the component based on the known values of the first and second currents and the measured values of the first, second, third and fourth voltages. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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57. A device configured to measure an impedance between first and second nodes in an electrical circuit, the device comprising:
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a) a voltage source configured to provide a voltage of known value;
b) a current source configured to provide a current of known value;
c) first and second probes, each connected to one of the known voltage and current sources, and configured to contact the respective first and second nodes to apply the known voltage and current to the first and second nodes;
d) a third common probe, connected to the voltage and current sources, configured to contact the circuit at a common node at a location that has an equal current flow with respect to the first and second nodes;
e) at least one voltage meter, configured to be connected to the first and second nodes, to measure voltages corresponding to the known voltage and current; and
f) a processor, operatively coupled to the at least one current source and the at least one voltage meter, capable of calculating the impedance based on the known values of the voltage and current and the measured values of the voltages.
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58. A method for measuring an impedance between first and second nodes in an electrical circuit, the method comprising the steps of:
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a) contacting the first and second nodes with first and second probes;
b) selecting a common node at a location which experiences an equal current flow with respect to the first and second nodes;
c) contacting the common node with a third probe;
d) applying a known current at the first node;
e) applying a known voltage at the second node;
f) measuring at least three voltages corresponding to the known current and voltage; and
g) calculating the impedance based on the known current and voltage and the measured values of the at least three voltages.
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Specification