Sensor interface with temperature signal processing
AssigneeAllegro MicroSystems, LLC
InventorsRichard Stary, Petr Hribal, Milan Valenta, Miloslav Trnka
Life of this patent
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Abstract
A sensor interface includes a signal path configured to receive a sensing element output signal from a sensing element and to generate an interface output signal indicative of a parameter sensed by the sensing element, an NTC interface and a diode interface. The NTC interface is configured to be coupled to an NTC element having a non-linear resistance over temperature and to generate an NTC signal indicative of a linearized version of the non-linear resistance of the NTC element and the diode interface configured to be coupled to a diode and to generate a diode signal indicative of an absolute temperature.
Claims18
A circuit comprising:
- a variable resistor coupled in series with a selected non-linear temperature coefficient (NTC) element;
- an operational amplifier having a non-inverting input to which an input voltage is applied, an inverting input coupled to the variable resistor, and an output at which an amplifier output signal indicative of a temperature sensed by the NTC element is generated, the amplifier output signal being a linearized version of the non-linear resistance of the NTC element;
- and
- a feedback resistor coupled between the output of the operational amplifier and the inverting input of the operational amplifier,
- wherein the variable resistor and feedback resistor are formed from a resistor network, the resistor network comprising
- a plurality of resistive elements coupled in series, with a first adjacent pair of the resistive elements interconnected at a switch junction and a second adjacent pair of the resistive elements interconnected at a transmission gate junction;
- a switch having a first terminal coupled to the switch junction, a second terminal coupled to the inverting input of the operational amplifier, and a control terminal that receives a control signal configuring a resistance of the variable resistor;
- and
- a transmission gate coupled between the output of the operational amplifier and the transmission gate junction, the transmission gate comprising a control terminal that receives a control signal configuring a resistance of the feedback resistor,
- wherein the resistance of the variable resistor and the resistance of the feedback resistor are configured based on a specification of the NTC element.
The circuit of 1, wherein when the switch and transmission gate is operated, the variable resistor comprises a first set of the resistive elements coupled between the NTC element and the inverting input of the operational amplifier, and the feedback resistor comprises a second set of the resistive elements coupled in a feedback path between the output of the operational amplifier and the inverting input of the operational amplifier.
A circuit comprising:
- a variable resistor coupled in series with a non-linear temperature coefficient (NTC) element;
- an operational amplifier having a non-inverting input to which an input voltage is applied, an inverting input coupled to the variable resistor, and an output at which an amplifier output signal indicative of a temperature sensed by the NTC element is generated, the amplifier output signal being a linearized version of the non-linear resistance of the NTC element;
- a feedback resistor coupled between the output of the operational amplifier and the inverting input of the operational amplifier;
- an analog-to-digital converter (ADC) configured to convert the amplifier output signal into a digital signal;
- and
- a resistor network comprising a plurality of resistive elements coupled in series between a supply voltage of the operational amplifier and a ground reference potential,
- wherein junctions between pairs of the resistive elements are coupled to an input to the ADC to generate intermediate reference voltages for the ADC, and
- wherein a junction between a pair of the resistive elements is coupled to the non-inverting input of the operational amplifier to apply the input voltage to the operational amplifier.
A circuit comprising:
- a variable resistor coupled in series with a non-linear temperature coefficient (NTC) element;
- an operational amplifier having a non-inverting input to which an input voltage is applied, an inverting input coupled to the variable resistor, and an output at which an amplifier output signal indicative of a temperature sensed by the NTC element is generated, the amplifier output signal being a linearized version of the non-linear resistance of the NTC element;
- a feedback resistor coupled between the output of the operational amplifier and the inverting input of the operational amplifier;
- an analog-to-digital converter (ADC) configured to convert the amplifier output signal into a digital signal;
- and
- a resistor network comprising
- a plurality of resistive elements coupled in series;
- junctions between pairs of the resistive elements;
- a first plurality of transmission gates, each of which is coupled between a respective one of the junctions and the output of the operational amplifier;
- and
- a second plurality of transmission gates, each of which is coupled between a respective one of the junctions and an input to the ADC.
Dependencies are inferred from the claim text.