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US 6,307,496 B1Granted
Sensing apparatus including an A/D conversion circuit for detecting a physical quantity
AssigneeDenso Corporation
InventorsToshio Ikuta, Noboru Endo, Takamoto Watanabe
Life of this patent
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Abstract
An analog multiplexer is provided to time divisionally process a reference signal Sa obtained from a reference voltage generating circuit, a temperature signal St obtained from a temperature detecting bridge circuit, and a sensor signal Sd obtained from a pressure detecting bridge circuit. These signals Sa, St and Sd are converted into digital data through a common differential amplification circuit and a common A/D conversion circuit. A correction circuit calculates an applied pressure value based on the digital data produced from the A/D conversion circuit, as a value corrected with reference to the temperature signal St and the reference signal Sa.
Claims19
A sensing apparatus comprising:
- a sensing circuit for generating a sensor signal having a voltage level responsive to a detected physical quantity;
- a temperature detecting circuit for generating a temperature signal having a voltage level responsive to a temperature of said sensing circuit;
- a reference voltage generating circuit for generating a reference signal having a constant voltage level irrespective of said detected physical quantity and the temperature of said sensing circuit;
- an analog multiplexer which receives each of said sensor signal, said temperature signal, and said reference signal and which selectively, successively outputs said sensor signal, said temperature signal, and said reference signal;
- amplification means which successively receives said sensor signal, said temperature signal, and said reference signal from said analog multiplexer and which amplifies said sensor signal, said temperature signal, and said reference signal to produce an amplified voltage signal;
- an A/D conversion circuit which receives the amplified voltage signal as a power source voltage and which converts said amplified voltage signal into digital data as an A/D conversion value during a predetermined time;
- and
- signal processing means for performing calculations based on said digital data in such a manner that the sensor signal corresponding to the detected physical quantity is corrected with respect to the temperature signal and with respect to said reference signal.
5 more elements
A sensing apparatus comprising:
- a sensing circuit for generating a sensor signal having a voltage level responsive to a detected physical quantity;
- a temperature detecting circuit for generating a temperature signal having a voltage level responsive to a temperature of said sensing circuit;
- a reference voltage generating circuit for generating a reference signal having a constant voltage level irrespective of said detected physical quantity and the temperature of said sensing circuit;
- an analog multiplexer which receives each of said sensor signal, said temperature signal, and said reference signal and which selectively, successively outputs said sensor signal, said temperature signal, and said sensing signal;
- amplification means which successively receives said sensor signal, said temperature signal, and said reference signal from said analog multiplexer and which amplifies said sensor signal, said temperature signal, and said reference signal to produce an amplified voltage;
- an A/D conversion circuit which receives the amplified voltage signal as a power source voltage and which converts said amplified voltage signal into digital data as an A/D conversion value during a predetermined time;
- and
- signal processing means for performing calculations based on said digital data in such a manner that the sensor signal corresponding to the detected physical quantity is corrected with respect to the temperature signal and with respect to said reference signal;
- wherein said A/D converting circuit includes a ring-gate delay circuit comprising a plurality of inverting circuits connected in a ring pattern and having an inverting operation time varying in accordance with said power source voltage, and
- each of said sensor signal, said temperature signal, and said reference signal, when serving as said power source voltage of said ring-gate delay circuit, is converted into digital data based on a pulse signal circulation frequency when a pulse signal is entered into said ring-gate delay circuit.
7 more elements
A sensing apparatus comprising:
- a sensing circuit for generating a sensor signal having a voltage level responsive to a detected physical quantity;
- a temperature detecting circuit for generating a temperature signal having a voltage level responsive to a temperature of said sensing circuit;
- a reference voltage generating circuit for generating a reference signal having a constant voltage level irrespective of said detected physical quantity and the temperature of said sensing circuit;
- an analog multiplexer which receives each of said sensor signal, said temperature signal, and said reference signal and which selectively, successively outputs said sensor signal, said temperature signal, and said sensing signal;
- amplification means which successively receives said sensor signal, said temperature signal, and said reference signal from said analog multiplexer and which amplifies said sensor signal, said temperature signal, and said reference signal to produce an amplified voltage;
- an A/D conversion circuit which receives the amplified voltage signal as a power source voltage and which converts said amplified voltage signal into digital data as an A/D conversion value during a predetermined time;
- and
- signal processing means for performing calculations based on said digital data in such a manner that the sensor signal corresponding to the detected physical quantity is corrected with respect to the temperature signal and with respect to said reference signal;
- wherein said physical quantity to be detected by said sensing circuit is pressure;
- wherein said signal processing means is for calculating a pressure P applied to said sensing circuit according to the following equation
- P={(T/A−b)*(−e/a)+D/A−f}/{(T/A−b)*c/a+d}
- where D, T and A are digital data respectively representing pressure information, temperature information and reference information converted by said A/D converting circuit, “c” represents a temperature coefficient in the sensitivity of the sensing circuit, “d” represents a room temperature sensitivity of the sensing circuit, “e” represents a temperature coefficient of an offset of a detected pressure value, “f” represents a room temperature offset value of the detected pressure value, “a” represents a temperature coefficient of a detected temperature value, and “b” represents a room temperature offset value of the detected temperature value.
9 more elements
A sensing apparatus comprising:
- a sensing circuit for generating a sensor signal having a voltage level responsive to a detected physical quantity;
- a temperature detecting circuit for generating a temperature signal having a voltage level responsive to a temperature of said sensing circuit;
- a reference voltage generating circuit for generating a reference signal having a constant voltage level irrespective of said detected physical quantity and the temperature of said sensing circuit;
- an A/D conversion circuit including a ring-gate delay circuit comprising a plurality of inverting circuits connected in a ring pattern and having an inverting operation time varying in accordance with said power source voltage, for converting each of said sensor signal, said temperature signal, and said reference signal, when serving as a power source voltage of said ring-gate delay circuit, into binary data based on a pulse signal circulation frequency when a pulse signal is entered into said ring-gate delay circuit;
- signal processing means for performing calculations based on said digital data in such a manner that the physical quantity corresponding to said sensor signal is corrected with reference to the temperature signal and said reference signal;
- and
- compensating means for compensating said power source voltage applied to said ring-gate delay circuit in said A/D conversion circuit, said compensating means including memory means for storing correction voltage data corresponding to offset amounts of said sensor signal, said temperature signal, and said reference signal under same conditions, wherein the power source voltage applied to said ring-gate delay circuit is corrected in accordance with said correction data when said sensor signal, said temperature signal, and said reference signal are selectively applied to said A/D conversion circuit as said power source voltage.
4 more elements
A sensing apparatus comprising:
- a pressure sensing circuit for generating a sensor signal having a voltage level responsive to a detected pressure;
- a temperature detecting circuit for generating a temperature signal having a voltage level responsive to a temperature of said pressure sensing circuit;
- a reference voltage generating circuit for generating a reference signal having a constant voltage level irrespective of said detected pressure and the temperature of said pressure sensing circuit;
- an analog multiplexer for selectively outputting said sensor signal, said temperature signal, and said reference signal;
- an A/D conversion circuit for converting said sensor signal, said temperature signal, and said reference signal into digital data;
- and
- signal processing means for calculating a pressure P applied to said pressure sensing circuit according to the following equation
- P={(T/A−b)×(−e/a)+D/A−f}/{(T/A−b)×c/a+d}
- where D, T and A are digital data respectively representing pressure information, temperature information, and reference information converted by said A/D converting circuit, “c” represents a temperature coefficient in the sensitivity of the pressure sensing circuit, “d” represents a room temperature sensitivity of the pressure sensing circuit, “e” represents a temperature coefficient of an offset of a detected pressure value, “f” represents a room temperature offset value of the detected pressure value, “a” represents a temperature coefficient of a detected temperature value, and “b” represents a room temperature offset value of the detected temperature value,
- wherein said analog multiplexer outputs said reference signal and said temperature signal prior to said sensor signal, and
- said signal processing means is for performing calculation steps relating to said reference information A and said temperature information T corresponding to said reference signal and said temperature signal in advance and at a later timing for performing calculation steps relating to said pressure information D corresponding to the sensor signal.
8 more elements
Dependencies are inferred from the claim text.