# US 2018/0321065 A1 · Oscillator based sensor interface circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321065 A1 - Document ID: US20180321065A1 - Status: Published application - Kind: A1 - Application number: 15/967,809 - Filed: 2018-05-01 - Published: 2018-11-08 - Earliest claimed: 2017-05-08 - Assignees: Melexis Technologies SA - Applicants: Melexis Technologies NV - Inventors: Johan VERGAUWEN - Web page: https://patentgrep.com/patent/US20180321065A1 ## CPC - G01D 18/00: Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00 - H03L 7/093: using special filtering or amplification characteristics in the loop (H03L7/087 - H03L7/091 take precedence) - H03L 7/099: concerning mainly the controlled oscillator of the loop - H03M 1/0604: {at one point, i.e. by adjusting a single reference value, e.g. bias or gain error (gain setting for range control H03M1/18)} - H03M 1/1014: {at one point of the transfer characteristic, i.e. by adjusting a single reference value, e.g. bias or gain error (gain setting for range control H03M1/18)} - H03M 1/60: with intermediate conversion to frequency of pulses - H03L 7/0802: {the loop being adapted for reducing power consumption (H03L7/14 takes precedence)} - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B) - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract An oscillator-based sensor interface circuit comprises at least two oscillators, at least one of which is arranged for receiving an electrical signal representative of an electrical quantity being a converted physical quantity, phase detection means arranged to compare output signals of the at least two oscillators and for outputting a digital phase detection output signal in accordance with the outcome of the comparing, a feedback element arranged for converting a representation of the digital phase detection output signal into a feedback signal used directly or indirectly to maintain a given relation between oscillator frequencies of the at least two oscillators, detection means for detecting a difference between the at least two oscillators; and at least one tuning element arranged for receiving the detected difference and for tuning at least one characteristic of the oscillator-based sensor interface circuit. ## Claims ### Claim 1 An oscillator-based sensor interface circuit arranged for offline error tuning comprising at least two oscillators, at least one of which is arranged for receiving an electrical signal representative of an electrical quantity, said electrical quantity being a converted physical quantity, and impacting said at least one oscillator's frequency, phase detection means arranged to compare output signals of said at least two oscillators and for outputting a digital phase detection output signal in accordance with the outcome of said comparing, said phase detector output signal also being an output signal of said oscillator-based sensor interface circuit, a feedback element arranged for receiving a representation of said digital phase detection output signal and for converting said representation into a feedback signal used directly or indirectly to maintain a given relation between oscillator frequencies of said at least two oscillators, means for detecting a difference between said at least two oscillators, at least one tuning element arranged for receiving said detected difference and for tuning at least one characteristic of the oscillator-based sensor interface circuit causing a change in oscillator frequency of at least one of said oscillators to reduce said detected difference. ### Claim 2 An oscillator-based sensor interface circuit arranged for online error tuning, comprising at least two oscillators, at least one of which is arranged for receiving an electrical signal representative of an electrical quantity, said electrical quantity being a converted physical quantity and impacting said at least one oscillator's frequency, chopping circuitry arranged for modulating said electrical signal representative of said electrical quantity with a chopping signal and for feeding said modulated electrical signal to said at least one oscillator, phase detection means arranged to compare output signals of said at least two oscillators and for outputting a digital phase detection output signal in accordance with the outcome of said comparing, said phase detector output signal also being an output signal of said oscillator-based sensor interface circuit, whereby said chopping circuitry is further arranged for demodulating said output signals before applying said output signals to said phase detection means or for demodulating said digital phase detection output signal, said oscillator-based sensor interface circuit further comprising a feedback element arranged for receiving a representation of said digital phase detection output signal and for converting said representation into a feedback signal used directly or indirectly to maintain a given relation between oscillator frequencies of said at least two oscillators, detection means for detecting a difference between said at least two oscillators based on said digital phase detection output signal, at least one tuning element arranged for receiving said detected difference and for tuning at least one characteristic of the oscillator-based sensor interface circuit causing a change in oscillator frequency of at least one of said oscillators to reduce said detected difference. ### Claim 3 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, further comprising a digital filter arranged for filtering said digital phase detection output signal and for applying said filtered digital phase detection output signal to said feedback element. ### Claim 4 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, comprising a sensing means arranged for converting said physical quantity comprised in a received signal into said electrical quantity and for outputting said electrical signal representative of said electrical quantity. ### Claim 5 (depends on 4) The oscillator-based sensor interface circuit as in claim 4, wherein said sensing means comprises a sensor arranged for receiving said signal comprising said physical quantity and a reference element arranged to generate a reference signal. ### Claim 6 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, wherein said feedback element comprises at least one current source. ### Claim 7 (depends on 4) The oscillator-based sensor interface circuit as in claim 4, comprising a Wheatstone bridge. ### Claim 8 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, wherein said phase detection means comprises a flip-flop. ### Claim 9 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, wherein said means is arranged for detecting said error by making a difference of the digital output signals obtained after said chopping. ### Claim 10 (depends on 4) The oscillator-based sensor interface circuit as in claim 4, wherein said feedback signal goes back to said sensing means. ### Claim 11 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, wherein said at least one tuning element arranged for gain tuning at least one of said at least two oscillators. ### Claim 12 (depends on 2) The oscillator-based sensor interface circuit as in claim 2, wherein said at least one tuning element arranged for offset tuning at least one of said at least two oscillators. ### Claim 13 (depends on 4) The oscillator-based sensor interface circuit as in claim 4, wherein said received signal is one of a pressure, a temperature, a force, a signal from an optical sensing means or from a magnetic sensing means.