# US 8,543,347 B2 · Self-correcting electronic sensor

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- Number: US 8,543,347 B2
- Document ID: US8543347B2
- Status: Granted
- Kind: B2
- Application number: 12/826,272
- Filed: 2010-06-29
- Published: 2011-12-29
- Granted: 2013-09-24
- Earliest claimed: 2010-06-29
- Assignees: Maxim Integrated Products, Inc.
- Applicants: Bert White
- Inventors: Bert White
- Web page: https://patentgrep.com/patent/US8543347B2

## CPC

- G01D 3/0365: {the undesired influence being measured using a separate sensor, which produces an influence related signal}
- G01K 7/42: Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature
- 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
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A temperature sensing circuit is described providing a low power temperature sensing system. The temperature sensing circuit provides a digital method for determining the temperature by analyzing the change in electrical response characteristics of a circuit device.

## Claims

### Claim 1

An electronic sensor configured to compensate for temperature and measure a physical parameter, the electronic sensor comprising:
a voltage bias circuit having at least one electrical output connection and first and second circuit elements, the first circuit element having a first physical characteristic of a first value and the second circuit element having a second physical characteristic of a second value, wherein the first and second values are set according to a first ratio relating the first value to the second value;
a voltage controlled oscillator connectable to the at least one electrical output connection of the voltage bias circuit;
a frequency sensor connectable to the voltage controlled oscillator, wherein in operation the frequency sensor provides a first digital value and a second digital value, indicative of an operating frequency of the voltage controlled oscillator at two different points in a linear operating region; and
a first digital physical parameter calculator circuit connectable to the frequency sensor to receive the first and second digital values, the first digital physical parameter calculator including digital logic configured to derive at least one digital value indicative of a measured physical parameter using the first and second digital values.

### Claim 2 (depends on 1)

The electronic sensor of claim 1, wherein the voltage bias circuit and the voltage controlled oscillator are integrated onto a single semiconductor die.

### Claim 3 (depends on 1)

The electronic sensor of claim 1, wherein the first and second circuit elements included in the voltage bias circuit are first and second diodes, and the first and second physical characteristics are respective sizes of the first and second diodes.

### Claim 4 (depends on 3)

The electronic sensor of claim 3, wherein the first and second diodes are parasitic PNP base-emitter diodes.

### Claim 5 (depends on 4)

The electronic sensor of claim 4, wherein the respective first and second values are corresponding areas of the first and second diodes.

### Claim 6 (depends on 3)

The electronic sensor of claim 3, further comprising:
a switch; and
a current source, wherein the switch is connectable to the current source, and the switch is selectively connectable to the first and second diodes.

### Claim 7 (depends on 6)

The electronic sensor of claim 6, wherein the at least one electrical output connection of the voltage bias circuit is made between the switch and the current source.

### Claim 8 (depends on 3)

The electronic sensor of claim 3, further comprising:
a first current source connectable in series to the first diode; and
a second current source connectable in series to the second diode,
wherein the voltage bias circuit includes first and second electrical output connections, the first output connection made between the first current source and the first diode, the second electrical output connection made between the second current source and the second diode.

### Claim 9 (depends on 1)

The electronic sensor of claim 1, wherein the first and second circuit elements included in the voltage bias circuit are first and second current sources, and the first and second values are respective magnitudes of currents produced by the first and second current sources in operation.

### Claim 10 (depends on 9)

The electronic sensor of claim 9, further comprising:
a switch; and
a diode, wherein the switch is connectable to the diode, and the switch is selectively connectable to the first and second current sources.

### Claim 11 (depends on 10)

The electronic sensor of claim 10, wherein at least one electrical output connection of the voltage bias circuit is made between the switch and diode.

### Claim 12 (depends on 1)

The electronic sensor of claim 1, wherein the voltage controlled oscillator is a ring oscillator.

### Claim 13 (depends on 1)

The electronic sensor of claim 1, where the frequency sensor is a counter circuit.

### Claim 14 (depends on 1)

The electronic sensor of claim 1, wherein the digital logic of the first digital physical parameter calculator circuit is configured to derive a digital value indicative of a temperature using the first and second digital values.

### Claim 15 (depends on 1)

The electronic sensor of claim 1, further comprising:
a voltage converter connectable to receive an input signal, the voltage converter having an electrical output connection connectable to the voltage controlled oscillator; and
a switch connectable to the voltage controlled oscillator, the switch selectively connectable to the electrical output connection of the voltage converter and the at least one electrical output connection of the voltage bias circuit,
wherein the digital logic of the first digital physical parameter calculator circuit is configured to derive a digital value indicative of a voltage using the first and second digital values and a third digital value.

### Claim 16

A method of measuring a physical parameter comprising:
generating a first voltage and a second voltage;
supplying the first voltage to a voltage controlled oscillator;
measuring a first value indicative of a fundamental frequency of the voltage controlled oscillator supplied with the first voltage;
supplying the second voltage to the voltage controlled oscillator;
measuring a second value indicative of the fundamental frequency of the voltage controlled oscillator supplied with second voltage; and
calculating a third value indicative of the physical parameter using the first and second values.

### Claim 17 (depends on 16)

The method of claim 16, wherein the first and second voltages are generated by driving current through first and second pn-junction diodes.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first and second pn-junction diodes are sized in relation to one another according to a ratio.

### Claim 19 (depends on 16)

The method of claim 16, wherein the physical parameter is a voltage, the method further comprising:
generating a third voltage;
supplying the third voltage to the voltage controlled oscillator;
measuring a fourth value indicative of the fundamental frequency of the voltage controlled oscillator supplied with the third voltage; and
wherein the third digital value indicative of the physical parameter is derived from the first, second and fourth values.

### Claim 20

An electronic sensor configured to compensate for temperature and measure a physical parameter, the electronic sensor comprising:
a voltage bias circuit having first and second circuit elements that are sized relative to one another according to a first ratio, wherein in operation the first and second circuit elements aid in establishing corresponding first and second output voltages;
a voltage controlled oscillator connectable to receive the first and second output voltages of the voltage bias circuit;
a frequency sensor connectable to the voltage controlled oscillator, wherein in operation the frequency sensor provides respective first and second measurements indicative of an operating frequency of the voltage controlled oscillator generated by the first and second output voltages; and
a first digital physical parameter calculator circuit connectable to the frequency sensor to receive the first and second measurements, the first digital physical parameter calculator including digital logic configured to derive at least one digital value indicative of a measured physical parameter using the first and second measurements.

### Claim 21 (depends on 20)

The electronic sensor of claim 20, wherein the voltage bias circuit and the voltage controlled oscillator are integrated onto a single semiconductor die.

### Claim 22 (depends on 20)

The electronic sensor of claim 20, wherein the first and second circuit elements included in the voltage bias circuit are first and second diodes.

### Claim 23 (depends on 22)

The electronic sensor of claim 22, further comprising:
a switch; and
a current source, wherein the switch is connectable to the current source, and the switch is selectively connectable to the first and second diodes.

### Claim 24 (depends on 22)

The electronic sensor of claim 22, further comprising:
a first current source connectable in series to the first diode; and
a second current source connectable in series to the second diode,
wherein the voltage bias circuit includes first and second electrical output connections, the first electrical output connection made between the first current source and the first diode, the second electrical output connection made between the second current source and the second diode.

### Claim 25 (depends on 20)

The electronic sensor of claim 20, wherein the first and second circuit elements included in the voltage bias circuit are first and second current sources.

### Claim 26 (depends on 25)

The electronic sensor of claim 25, further comprising:
a switch; and
a diode, wherein the switch is connectable to the diode, and the switch is selectively connectable to the first and second current sources.

### Claim 27 (depends on 20)

The electronic sensor of claim 20, wherein the digital logic of the first digital physical parameter calculator circuit is configured to derive a digital value indicative of a temperature using the first and second measurements.

### Claim 28 (depends on 20)

The electronic sensor of claim 20, further comprising:
a voltage converter connectable to receive an input signal, the voltage converter having an electrical output connection connectable to the voltage controlled oscillator; and
a switch connectable to the voltage controlled oscillator, the switch selectively connectable to the electrical output connection of the voltage converter and at least one electrical output connection of the voltage bias circuit,
wherein the digital logic of the first digital physical parameter calculator circuit is configured to derive a digital value indicative of a voltage using the first and second measurements and a third measurement.

### Claim 29

An electronic sensor configured to compensate for temperature comprising:
a voltage bias circuit having first and second circuit elements that are sized relative to one another according to a first ratio, wherein in operation the voltage bias circuit provides first and second output voltages;
a voltage controlled oscillator connectable to receive the first and second output voltages;
a frequency sensor connectable to the voltage controlled oscillator, wherein in operation the frequency sensor provides respective first and second measurements indicative of an operating frequency; and
a first digital physical parameter calculator circuit connectable to the frequency sensor to receive the first and second measurements, wherein in operation the digital physical parameter calculator derives at least one digital value indicative of a measured physical parameter using the first and second measurements.

### Claim 30 (depends on 29)

The electronic sensor of claim 29, wherein the voltage bias circuit and the voltage controlled oscillator are integrated onto a single semiconductor die.

### Claim 31 (depends on 29)

The electronic sensor of claim 29, wherein the first and second circuit elements included in the voltage bias circuit are first and second diodes.

### Claim 32 (depends on 31)

The electronic sensor of claim 31, further comprising:
a switch; and
a current source, wherein the switch is connectable to the current source, and the switch is selectively connectable to the first and second diodes.

### Claim 33 (depends on 31)

The electronic sensor of claim 31, further comprising:
a first current source connectable in series to the first diode; and
a second current source connectable in series to the second diode,
wherein the voltage bias circuit includes first and second electrical output connections, the first electrical output connection made between the first current source and the first diode, the second electrical output connection made between the second current source and the second diode.

### Claim 34 (depends on 29)

The electronic sensor of claim 29, wherein the first and second circuit elements included in the voltage bias circuit are first and second current sources.

### Claim 35 (depends on 34)

The electronic sensor of claim 34, further comprising:
a switch; and
a diode, wherein the switch is connectable to the diode, and the switch is selectively connectable to the first and second current sources.

### Claim 36 (depends on 29)

The electronic sensor of claim 29, wherein a digital logic of the first digital physical parameter calculator circuit is configured to derive a digital value indicative of a temperature using the first and second measurements.

### Claim 37 (depends on 29)

The electronic sensor of claim 29, further comprising:
a voltage converter connectable to receive an input signal, the voltage converter having an electrical output connection connectable to the voltage controlled oscillator; and
a switch connectable to the voltage controlled oscillator, the switch selectively connectable to the electrical output connection of the voltage converter and at least one electrical output connection of the voltage bias circuit,
wherein a digital logic of the first digital physical parameter calculator circuit is configured to derive a digital value indicative of voltage using the first and second measurements and a third measurement.