# US 2019/0377012 A1 · Precision current sensing using low cost sense resistance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0377012 A1 - Document ID: US20190377012A1 - Status: Published application - Kind: A1 - Application number: 16/398,237 - Filed: 2019-04-29 - Published: 2019-12-12 - Earliest claimed: 2018-06-08 - Assignees: Chrontel, Inc. - Applicants: Chrontel Inc. - Inventors: David Chee-Fai Soo; Mohammad Yunus; Yiwei Wang - Web page: https://patentgrep.com/patent/US20190377012A1 ## CPC - G01R 19/25: using digital measurement techniques - G01R 1/203: {Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts (resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R)} - G01R 19/0092: {Measuring current only} - G01R 19/2506: {Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values (G01R19/003 takes precedence); Details concerning sampling, digitizing or waveform capturing (displaying waveforms G01R13/00; analog sampling G01R19/0053)} - G01R 35/005: {Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references (G01R33/0035, G01R35/002 take precedence)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract Apparatus and associated methods relate to configuring a circuit to sense current in a low-cost non-precision resistance, calibrating the circuit to correct inaccuracy measured in the sensed current, and measuring with the corrected circuit the precise current sensed in the low-cost non-precision resistance. In an illustrative example, the low-cost non-precision resistance may be a metal trace on a printed circuit board. The circuit may be calibrated, for example, over a range of currents or temperatures, permitting automatic adjustment to a wide range of non-precision resistance parameter values and environmental conditions. In some examples, correcting coefficients may be adapted to compensate for resistance non-linearities, which may include skin effect or self-heating. Some embodiments may verify the calibrated correction over a range of current and temperature. Various examples may advantageously provide high precision measurement at reduced cost, based on calibrating a circuit to obtain corrected measurement sensed with a low-cost non-precision resistance. ## Claims ### Claim 1 A process, comprising: a method to accurately measure current in a low-cost non-precision current sense resistance, comprising: configuring a circuit to sense current in a low-cost non-precision current sense resistance; calibrating the circuit to correct inaccuracy measured in the sensed current; and, measuring with the calibrated circuit the precise current sensed in the low-cost non-precision current sense resistance. ### Claim 2 (depends on 1) The method of claim 1, in which the circuit further comprises a current supply connected in series with the low-cost non-precision current sense resistance. ### Claim 3 (depends on 2) The method of claim 2, in which configuring the circuit further comprises adapting the circuit to measure the voltage drop generated by the current supply across the low-cost non-precision current sense resistance when the current supply is activated. ### Claim 4 (depends on 3) The method of claim 3, in which calibrating the circuit further comprises comparing the measured voltage drop with a predetermined ideal voltage drop. ### Claim 5 (depends on 3) The method of claim 3, in which calibrating the circuit further comprises measuring the voltage drop generated by a current determined as a percentage of the current supply full scale current. ### Claim 6 (depends on 5) The method of claim 5, in which calibrating the circuit further comprises measuring the voltage drop generated by the current at a plurality of temperatures. ### Claim 7 (depends on 1) The method of claim 1, in which calibrating the circuit further comprises calculating calibration coefficients determined as a function of the current sensed in the low-cost non-precision current sense resistance. ### Claim 8 An apparatus, comprising: a precision current sensing system configured to accurately measure current, comprising: a current sensing element; a current supply connected in series with the current sensing element; a processor, operably coupled with the current supply to govern the current supplied by the current supply; wherein, the processor is operably coupled with the current sensing element to measure the voltage drop generated across the current sensing element when the current supply is activated; and, a memory that is not a transitory propagating signal, the memory connected to the processor and encoding computer readable instructions, including processor executable program instructions, the computer readable instructions accessible to the processor, wherein the processor executable program instructions, when executed by the processor, cause the processor to perform operations comprising: sense current in the current sensing element; correct inaccuracy measured in the sensed current; and, measure the precise current sensed in the current sensing element with the measured inaccuracy corrected. ### Claim 9 (depends on 8) The apparatus of claim 8, in which the current sensing element further comprises a bond wire of an integrated circuit package. ### Claim 10 (depends on 8) The apparatus of claim 8, in which the current sensing element is configured on a printed circuit board, or on an integrated circuit package lead frame, or on an integrated circuit itself. ### Claim 11 (depends on 8) The apparatus of claim 8, in which the current sensing element further comprises: a plurality of connections, comprising: a first set of more than one connection configured to force current in the sensing element; and, a second set of more than one connection distinct from the first set of more than one connection, the second set of more than one connection configured to sense voltage drop across the sensing element. ### Claim 12 (depends on 8) The apparatus of claim 8, in which the current sensing element further comprises sensor signal conditioning circuitry configured to correct sensing element non-ideality over temperature, sensing current value, and variation in the sensing element material. ### Claim 13 (depends on 8) The apparatus of claim 8, in which the operations performed by the processor further comprise: measure, at a plurality of temperatures, the voltage drop generated by a current determined as a percentage of the current supply full scale current. ### Claim 14 (depends on 8) The apparatus of claim 8, in which the operations performed by the processor further comprise: calculate calibration coefficients determined as a function of the current sensed in the current sensing element. ### Claim 15 An apparatus, comprising: a precision current sensing system configured to accurately measure current in a current sense resistance, comprising: a current sensing element, comprising: a low-cost non-precision current sense resistance; and, sensor signal conditioning circuitry operably coupled with the low-cost non-precision current sense resistance, wherein the signal conditioning circuitry is configured to correct sensing element non-ideality over temperature, sensing current value, and variation in the sensing element material; and, a current supply connected in series with the low-cost non-precision current sense resistance; a processor, operably coupled with the current supply to govern the current supplied by the current supply; wherein, the processor is operably coupled with the low-cost non-precision current sense resistance to measure the voltage drop generated across the low-cost non-precision current sense resistance when the current supply is activated; and, a memory that is not a transitory propagating signal, the memory connected to the processor and encoding computer readable instructions, including processor executable program instructions, the computer readable instructions accessible to the processor, wherein the processor executable program instructions, when executed by the processor, cause the processor to perform operations comprising: sense current in the low-cost non-precision current sense resistance, based on measuring the voltage drop generated by the current supply across the low-cost non-precision resistance when the current supply is activated; correct inaccuracy measured in the sensed current, based on calculating calibration coefficients determined as a function of the current sensed in the low-cost non-precision resistance by measuring at a plurality of temperatures the voltage drop generated by a plurality of currents determined as percentages of the current supply full scale current; and, measure the precise current sensed in the low-cost non-precision current sense resistance with the measured inaccuracy corrected. ### Claim 16 (depends on 15) The apparatus of claim 15, in which the low-cost non-precision current sense resistance further comprises a bond wire of an integrated circuit package. ### Claim 17 (depends on 15) The apparatus of claim 15, in which the plurality of currents further comprises a number of current values determined as a function of a sense resistor characteristic useful to compute a corrected current value proportional to the real value of the sensed current. ### Claim 18 (depends on 15) The apparatus of claim 15, in which the percentages of the current supply full scale current further comprises a percentage of the current supply full scale current determined as a function of a sense resistor characteristic useful to compute a corrected current value proportional to the real value of the sensed current. ### Claim 19 (depends on 15) The apparatus of claim 15, in which correct inaccuracy further comprises verify the correction of the sensed voltage of the low-cost non-precision current sense resistance over various values of the accurate forced current as well as over various temperatures. ### Claim 20 (depends on 15) The apparatus of claim 15, in which measure the precise current further comprises compute the precise current value as a function of the calculated calibration coefficients.