Bi-directional high side current sense measurement
First Claim
1. A system for measuring a voltage drop between two nodes in an electrical circuit, the system comprising:
- a switched capacitor integrator (SCI) coupled to the two nodes and configured to alternately (a) capture samples of charge onto a set of sampling capacitors and (b) selectively accumulate the charge samples onto a pair of integration capacitors, wherein the charge samples include a first charge sample based on the voltage drop and a second charge sample based on a reference voltage, wherein said selectively accumulating includes accumulating the first charge sample, wherein said selectively accumulating includes accumulating the second charge sample only if a digital indicator signal equals one, wherein the SCI is configured to generate an analog output signal that corresponds to a total accumulated charge on the integration capacitors;
a comparator circuit configured to generate the digital indicator signal based on the analog output signal, wherein the digital indicator signal indicates whether the analog output signal is positive or negative at each active edge of a clock signal;
a counter configured to count a number of ones occurring in the digital indicator signal during a measurement interval, wherein, at the end of the measurement interval, the number represents a measure of the voltage drop.
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Abstract
A system for measuring a voltage drop between two nodes in an electrical circuit, comprising a switched capacitor integrator (SCI), a comparator and a counter. The SCI alternately (a) captures charge onto a set of sampling capacitors and (b) selectively accumulates/transfers the charge onto a pair of integration capacitors, where the charge includes a first portion that is based on the voltage drop and a second portion that depends on a digital indicator signal. The comparator generates the digital indicator signal based on whether an analog output of the SCI is positive or negative. The counter counts a number of ones occurring in the digital indicator signal during a measurement interval. At the end of the measurement interval, the count value represents a measure of the voltage drop. Knowing the resistance between the two nodes, the voltage drop may be converted into a current measurement.
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Citations
22 Claims
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1. A system for measuring a voltage drop between two nodes in an electrical circuit, the system comprising:
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a switched capacitor integrator (SCI) coupled to the two nodes and configured to alternately (a) capture samples of charge onto a set of sampling capacitors and (b) selectively accumulate the charge samples onto a pair of integration capacitors, wherein the charge samples include a first charge sample based on the voltage drop and a second charge sample based on a reference voltage, wherein said selectively accumulating includes accumulating the first charge sample, wherein said selectively accumulating includes accumulating the second charge sample only if a digital indicator signal equals one, wherein the SCI is configured to generate an analog output signal that corresponds to a total accumulated charge on the integration capacitors; a comparator circuit configured to generate the digital indicator signal based on the analog output signal, wherein the digital indicator signal indicates whether the analog output signal is positive or negative at each active edge of a clock signal; a counter configured to count a number of ones occurring in the digital indicator signal during a measurement interval, wherein, at the end of the measurement interval, the number represents a measure of the voltage drop. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for measuring a voltage drop between two nodes in an electrical circuit, the method comprising:
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capturing samples of charge onto a set of sampling capacitors; selectively accumulating the charge samples onto a pair of integration capacitors in an integrator circuit, wherein the charge samples include a first charge sample that is based on the voltage drop and a second charge that is based on a reference voltage, where said selectively accumulating includes accumulating the first charge sample, wherein said selectively accumulating includes accumulating the second charge sample only if a digital indicator signal equals one; generating the digital indicator signal based on an analog output of the integrator circuit, wherein the digital indicator signal indicates whether the analog output is positive or negative at each active edge of a clock signal; counting a number of ones occurring in the digital indicator signal during a measurement interval, wherein, at the end of the measurement interval, the number represents a measure of the voltage drop. - View Dependent Claims (15, 16, 17)
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18. A system for measuring a voltage drop between two nodes in an electrical circuit, the system comprising:
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a switched capacitor integrator (SCI) coupled to the two nodes and configured to alternately (a) capture charge onto a set of sampling capacitors and (b) transfer the charge onto a pair of integration capacitors, wherein the charge includes at least a first charge component that is based on the voltage drop, wherein the SCI is configured to generate an output signal that represents an amplification of the voltage drop; an analog-to-digital converter (ADC) configured to capture measurements of the output signal, wherein the measurements of the output signal represents measurements of the voltage drop, wherein the SCI is configured to zero any charge on the integration capacitors after the ADC captures each measurement of the output signal. - View Dependent Claims (19, 20, 21, 22)
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Specification