# US 2006/0232456 A1 · Analog-to-digital conversion apparatus and sensing apparatus having the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2006/0232456 A1 - Document ID: US20060232456A1 - Status: Published application - Kind: A1 - Application number: 11/386,765 - Filed: 2006-03-23 - Published: 2006-10-19 - Earliest claimed: 2005-03-30 - Assignees: Denso Corporation - Inventors: Kenji Morikawa - Web page: https://patentgrep.com/patent/US20060232456A1 ## CPC - H03M 1/0619: {by dividing out the errors, i.e. using a ratiometric arrangement} - G04F 10/005: {Time-to-digital converters [TDC] (analog-to-digital converters with intermediate conversion to time or phase H03M1/50, H03M1/60)} - H03M 1/502: {using tapped delay lines} - H03M 1/60: with intermediate conversion to frequency of pulses - 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) - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) ## Abstract A sensing apparatus includes a reference voltage generation circuit for generating a first and a second reference signals having different constant voltage levels, an A/D conversion circuit having a ring-gate-delay circuit, and a correction circuit for correcting an output value of the A/D conversion circuit. The A/D conversion circuit converts a load signal and the first and second reference signals to digital data based on the number of times a pulse signal input to the ring-gate-delay circuit circulates through the ring-gate-delay circuit. The correction circuit corrects the output value based on a ratio of a first difference between the digital data to a second difference between the digital data. ## Claims ### Claim 1 An analog-to-digital conversion apparatus, comprising: a reference voltage generation circuit for generating a first reference signal having a first constant voltage level and a second reference signal having a second constant voltage level different from the first constant voltage level; an analog-to-digital conversion circuit including a ring-gate-delay circuit having a plurality of inverting circuits that perform an inverting operation at a variable speed depending on a power voltage of the ring-gate-delay circuit and are connected in a ring pattern, the analog-to-digital conversion circuit converting a physical quantity signal having a voltage level varying with an amount of a physical quantity, the first reference signal, and the second reference signal, each signal being provided to the ring-gate-delay circuit as the power voltage, to a physical quantity data, a first reference data, and a second reference data, respectively, based on the number of times a pulse signal input to the ring-gate-delay circuit circulates through the ring-gate-delay circuit; and a signal processing means for calculating an output value corresponding to the physical quantity based on a ratio between a first deference and a second difference, wherein the first difference is a difference between any single pair from the physical quantity data, the first reference data, and the second reference data, and the second difference is a difference between one of other pairs from the physical quantity data, the first reference data, and the second reference data. ### Claim 2 (depends on 1) The analog-to-digital conversion apparatus according to claim 1, wherein one of the first and second differences is a difference between the first reference data and the second reference data. ### Claim 3 A sensing apparatus, comprising: a sensing circuit for generating a physical quantity signal having a voltage level varying with an amount of a physical quantity to be measured; a reference voltage generation circuit for generating a first reference signal having a first constant voltage level and a second reference signal having a second constant voltage level different from the first constant voltage level; an analog-to-digital conversion circuit including a ring-gate-delay circuit having a plurality of inverting circuits that perform an inverting operation at a variable speed depending on a power voltage of the ring-gate-delay circuit and are connected in a ring pattern, the analog-to-digital conversion circuit converting the physical quantity signal, the first reference signal, and the second reference signal, each signal being provided to the ring-gate-delay circuit as the power voltage, to a physical quantity data, a first reference data, and a second reference data, respectively, based on the number of times a pulse signal input to the ring-gate-delay circuit circulates through the ring-gate-delay circuit; a signal processing means for calculating an output value corresponding to the physical quantity based on a ratio between a first deference and a second difference; and a storing means for storing a relation between a correction value for correcting a temperature dependence of the ratio on the sensing circuit and the first reference data or the second reference data, wherein the first difference is a difference between any single pair from the physical quantity data, the first reference data, and the second reference data, the second difference is a difference between one of other pairs from the physical quantity data, the first reference data, and the second reference data, and the signal processing means calculates the correction value of the ratio from the first reference data or the second reference data by using the relation stored by the storing means, corrects the ratio based on the correction value, and calculates the output value based on the corrected ratio. ### Claim 4 (depends on 3) The sensing apparatus according to claim 3, wherein the reference voltage generation circuit includes at least two resistors across which a power source voltage is applied, and generates the first and second reference signals by dividing the power source voltage by a ratio between resistances of the resistors. ### Claim 5 (depends on 3) The sensing apparatus according to claim 3, further comprising: an analog multiplexer for repeatedly outputting the physical quantity signal, the first reference signal, and the second reference signal to the analog-to-digital conversion circuit in a predetermined order. ### Claim 6 A sensing apparatus, comprising: a sensing circuit for generating a physical quantity signal having a voltage level varying with an amount of a physical quantity to be measured; a reference voltage generation circuit for generating a first reference signal having a first constant voltage level and a second reference signal having a second constant voltage level different from the first constant voltage level; an analog-to-digital conversion circuit including a ring-gate-delay circuit having a plurality of inverting circuits that perform an inverting operation at a variable speed depending on a power voltage of the ring-gate-delay circuit and are connected in a ring pattern, the analog-to-digital conversion circuit converting the physical quantity signal, the first reference signal, and the second reference signal, each signal being provided to the ring-gate-delay circuit as the power voltage, to a physical quantity data, a first reference data, and a second reference data, respectively, based on the number of times a pulse signal input to the ring-gate-delay circuit circulates through the ring-gate-delay circuit; a signal processing means for calculating an output value corresponding to the physical quantity based on a ratio between a first deference and a second difference; and an analog multiplexer for repeatedly outputting the physical quantity signal, the first reference signal, and the second reference signal to the analog-to-digital conversion circuit in a predetermined order, wherein the signal processing means calculates the ratio by using one actual data of the physical quantity data, the first reference data, and the second reference data, and two estimated data of others of the physical quantity data, the first reference data, and the second reference data, each of the two estimated data is estimated from a previous data corresponding to a previous signal that is input to the analog-to-digital conversion circuit just before a signal converted to the actual data is input thereto and a next data corresponding to a next signal that is input to the analog-to-digital conversion circuit just after the signal converted to the actual data is input thereto, the first difference is a difference between any single pair from the one actual data and the two estimated data, and the second difference is a difference between one of other pairs from the one actual data and the two estimated data. ### Claim 7 (depends on 6) A sensing apparatus according to claim 6, wherein the each of the two estimated data is estimated as an average of the previous data and the next data.