CN115574962B - Temperature sensor and correction method thereof - Google Patents
Temperature sensor and correction method thereof Download PDFInfo
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- CN115574962B CN115574962B CN202110689949.7A CN202110689949A CN115574962B CN 115574962 B CN115574962 B CN 115574962B CN 202110689949 A CN202110689949 A CN 202110689949A CN 115574962 B CN115574962 B CN 115574962B
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- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000012937 correction Methods 0.000 title claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 claims abstract description 19
- 238000013507 mapping Methods 0.000 claims abstract description 17
- 238000009533 lab test Methods 0.000 claims abstract description 15
- 238000009966 trimming Methods 0.000 claims abstract description 12
- 238000012360 testing method Methods 0.000 claims abstract description 4
- 238000013461 design Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000013256 coordination polymer Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K15/00—Testing or calibrating of thermometers
- G01K15/005—Calibration
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- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The invention discloses a temperature sensor and a correction method thereof, wherein the method comprises the following steps: determining a mapping table of a reference voltage Vref and a slope by laboratory testing for a determination process; determining a trimming value Vref_trim of a reference voltage Vref of the triode circuit through laboratory test, wherein the trimming value Vref_trim enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be close to a target temperature Ttarget; during production, the temperature of Die or Chip is maintained near the target temperature Ttarget, the reference voltage Vref output by a triode circuit is measured, and the corresponding slope is determined by searching the mapping table; the detected slope is set as the slope used in correction of each Die or Chip, and the whole method is simple and easy to realize.
Description
Technical Field
The invention relates to the field of temperature sensors, in particular to a temperature sensor with low cost and easy realization and a correction method thereof.
Background
The core of the temperature sensor chip (temperature sensor IC) is a sigma-delta ADC. As shown in fig. 1, the analog voltages avbe and Vref generated by the triode circuit are converted into serial code streams bs with corresponding duty ratios by a sigma-delta modulator (sigma-delta modulator), and then downsampled into N-bit binary parallel output data Dout by a digital filter, and the parallel output data Dout includes:
wherein Vref is zero temperature coefficient bandgap reference voltage, ΔVbe is a thermal voltage proportional to absolute temperature, expressed as:
where a is the proportionality coefficient constant (determined by the process and circuit design), K is the Boltzmann's constant, q is the electron charge, and T is the absolute temperature.
The accuracy of a temperature sensor is generally determined by two aspects: circuit design and correction. On the premise of ensuring that the design precision of the early-stage circuit is enough, the precision of the final product is determined by the later-stage correction work.
Disclosure of Invention
The invention aims to solve the technical problem of providing a temperature sensor with low cost and easy realization and a correction method thereof aiming at the requirements of the prior art.
The technical scheme adopted for solving the technical problems is as follows: a temperature sensor calibration method is constructed, the temperature sensor comprises a triode circuit, a sigma-delta modulator, a digital filter and a calibrator which are sequentially connected, the triode circuit outputs zero temperature coefficient band gap reference voltage Vref and thermal voltage delta Vbe which is proportional to absolute temperature to the sigma-delta modulator, the digital filter outputs data Dout to the calibrator for calibration, and the calibrator calibrates the data Dout based on a set slope to obtain calibration data Dfinal, the method comprises:
for a determining process, determining a mapping table of a reference voltage Vref and a slope by laboratory test in advance;
determining a trimming value Vref_trim of a reference voltage Vref of the triode circuit through laboratory test, wherein the trimming value Vref_trim enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be close to a target temperature Ttarget;
during production, the temperature of Die or Chip is maintained near the target temperature Ttarget, the reference voltage Vref output by a triode circuit is measured, and the corresponding slope is determined by searching the mapping table;
the slope found is set as the slope used when each Die or Chip is corrected.
Preferably, the zero temperature coefficient point is determined by: and changing the temperature of the temperature sensor, measuring the reference voltage Vref output by the triode circuit, and manufacturing a relation curve of Vref and the temperature by taking the temperature as an abscissa and taking the measured reference voltage Vref as an ordinate, wherein the extreme point of the relation curve of Vref and the temperature is the zero temperature coefficient point.
Preferably, the look-up table for determining the reference voltage Vref and the slope in advance through laboratory tests includes: setting the temperature of a temperature sensor as a target temperature Ttarget, sequentially adding different reference voltages Vref to the sigma-delta modulator, measuring data Dout output by the digital filter, manufacturing straight lines corresponding to the different reference voltages Vref when the absolute temperature is taken as an abscissa and the data Dout is taken as an ordinate, and determining the slope of each straight line to obtain a mapping table of the reference voltages Vref and the slope.
Preferably, the vicinity of the target temperature Ttarget refers to a temperature zone having the target temperature Ttarget as a center temperature.
In a further aspect, the invention also provides a temperature sensor, characterized in that the correction of the temperature sensor is carried out in the production process of the sensor by means of a method based on any one of the preceding claims.
Preferably, the calibrator calibrates the data Dout based on the following calculation formula:
the low-cost and easy-to-implement temperature sensor and the correction method thereof have the following beneficial effects: the invention determines a mapping table of a reference voltage Vref and a slope in advance through laboratory tests, determines a trimming value Vref_trim of the reference voltage Vref of the triode circuit in advance through laboratory tests, enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be near a target temperature Ttarget, maintains the temperature of a Die or a Chip to be near the target temperature Ttarget during production, measures the reference voltage Vref output by the triode circuit, and determines a corresponding slope by searching the mapping table; the detected slope is set as the slope used in correction of each Die or Chip, and the whole method is simple and easy to realize.
Drawings
For a clearer description of an embodiment of the invention or of a technical solution in the prior art, the drawings that are needed in the description of the embodiment or of the prior art will be briefly described, it being obvious that the drawings in the description below are only embodiments of the invention, and that other drawings can be obtained, without inventive effort, by a person skilled in the art from the drawings provided:
FIG. 1 is a schematic diagram of a temperature sensor;
FIG. 2 is a flow chart of a temperature sensor calibration method of the present invention;
FIG. 3 is a schematic diagram of a temperature sensor calibration method of the present invention;
FIG. 4 is a schematic diagram showing the correspondence between Verf and Dout;
fig. 5 is a graph of Vref versus temperature.
Detailed Description
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Exemplary embodiments of the present invention are illustrated in the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The invention has the following general ideas: firstly, a mapping table of a reference voltage Vref and a slope is determined in advance through laboratory tests aiming at a determining process; then, a trimming value Vref_trim of the reference voltage Vref of the triode circuit is determined through laboratory test, and the trimming value Vref_trim enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be close to the target temperature Ttarget; during production, the temperature of Die or Chip is maintained near the target temperature Ttarget, the reference voltage Vref output by a triode circuit is measured, and the corresponding slope is determined by searching the mapping table; finally, the detected slope is set as the slope used in correction of each Die or Chip, and the whole method is simple and easy to realize.
In order to better understand the above technical solutions, the following detailed description will be made with reference to the accompanying drawings and specific embodiments, and it should be understood that specific features in the embodiments and examples of the present invention are detailed descriptions of the technical solutions of the present application, and not limit the technical solutions of the present application, and the technical features in the embodiments and examples of the present invention may be combined with each other without conflict.
Example 1
Referring to fig. 2, the temperature sensor correction method of the present embodiment includes:
s101: for a certain process, a mapping table of the reference voltage Vref and the slope is determined in advance by laboratory tests.
It will be appreciated that there are a plurality of fabrication processes for the temperature sensor, and therefore the calibration method according to the present invention is required to be performed separately for each fabrication process, and therefore, a specific process must be determined first.
Referring to fig. 3, the temperature sensor includes a triode circuit, a sigma-delta modulator, a digital filter, and a calibrator connected in sequence. The triode circuit outputs a reference voltage Vref and a thermal voltage avbe proportional to absolute temperature to the sigma-delta modulator,a is a proportionality coefficient constant (determined by the process and circuit design), K is a Boltzmann's constant, q is the electron charge amount, and T is the absolute temperature. The sigma-delta modulator converts the received reference voltage Vref and thermal voltage ΔVbe into a serial code stream bs with corresponding duty ratio, and then downsamples the serial code stream bs into N-bit binary parallel output data Dout through a digital filter:the digital filter outputs data Dout to a calibrator, and the calibrator calibrates the data Dout based on a set slope to obtain calibration data Dfinal: />
I.e. Dout is the output of the digital filter and Dfinal is the corrected output. The delta Vbe has good process stability, is little affected by process diffusion, and can ensure good consistency between the same batch and different batches. Therefore, the present embodiment adopts a single point temperature correction method, and the temperature is referred to as a target temperature (Ttarget). Assuming that the circuit design accuracy is sufficient, the relationship between Ttarget and Vref is as in fig. 4.
Wherein,the Ttarget is expressed as a data format with the LSB of b K degrees, and the data format comprisesFurther denoted slide +.>Based on the target temperature Ttarget, the output corrected by the corrector is: />
Thus, in this embodiment, the look-up table for determining the reference voltage Vref and the slope in advance through laboratory tests includes: setting the temperature of a temperature sensor (for example, setting the temperature sensor to an incubator, and setting the temperature of the incubator to be the temperature of the sensor) as a target temperature Ttarget, sequentially adding different reference voltages Vref to the sigma-delta modulator, measuring data Dout output by the digital filter, taking absolute temperature as an abscissa and taking the data Dout as an ordinate, manufacturing straight lines corresponding to the added different reference voltages Vref (the straight lines are determined by the Ttarget and a coordinate point and an origin point determined by the data Dout output by the digital filter at the moment), and determining the slope of each straight line to obtain a mapping table of the reference voltages Vref and the slope.
S102: determining a trimming value Vref_trim of a reference voltage Vref of the triode circuit through laboratory test, wherein the trimming value Vref_trim enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be close to a target temperature Ttarget;
referring to fig. 5, the zero temperature coefficient point is determined in the following manner: changing the temperature of the temperature sensor (for example, putting the temperature sensor into an incubator, changing the temperature of the incubator can change the temperature of the sensor), measuring the reference voltage Vref output by the triode circuit, and manufacturing a relation curve of Vref and the temperature by taking the temperature as an abscissa and taking the measured reference voltage Vref as an ordinate, wherein the extreme point of the relation curve of Vref and the temperature is the zero temperature coefficient point.
It can be understood that, in the triode circuit, a bandgap reference circuit is generally used to generate the reference voltage Vref, and the temperature coefficient of the reference voltage Vref is easily modified, that is, in this embodiment, a suitable modification value vref_trim is found by trying different modification values vref_trim, so that the extreme point of the relationship curve of Vref and temperature generated is near Ttarget.
S103: during production, the temperature of Die (CP stage) or Chip (FT stage) is maintained near the target temperature Ttarget, the reference voltage Vref output by the triode circuit is measured, and the corresponding slope is determined by searching the mapping table;
test in fig. 3 represents the measurement of the reference voltage Vref output by the triode circuit by the voltage measuring instrument.
It is understood that the vicinity of the target temperature Ttarget described herein refers to a temperature zone centered around the target temperature Ttarget, and the length of the temperature zone is typically several degrees celsius.
The method of this embodiment has low requirements on the test environment and the measuring instrument in engineering production, for example, in this step, only the Die or Chip temperature needs to be controlled near Ttarget, because Vref is approximately zero temperature coefficient near Ttarget. For another example, in this step, a very high precision measuring instrument is not required for measuring the reference voltage Vref output from the triode circuit, for example, the target temperature Ttarget is about 358K (85 ℃), vref is about 1.2V, and the precision of 0.3 ℃ is required at Ttarget, and the measurement precision of Vref is required to be aboutAnd (3) obtaining the product.
S104: the slope found is set as the slope used when each Die or Chip is corrected.
As mentioned above, the calibrator calibrates the data Dout based on the following calculation formula:thus, the present embodiment finds the appropriate slope by looking up a table based on +.>Data Dout is calibrated.
Example two
The embodiment discloses a temperature sensor, wherein the method based on the first embodiment is adopted in the production process of the sensor to realize the correction of the temperature sensor.
In summary, the low-cost and easy-to-implement temperature sensor and the correction method thereof have the following beneficial effects: the invention determines a mapping table of a reference voltage Vref and a slope in advance through laboratory tests, determines a trimming value Vref_trim of the reference voltage Vref of the triode circuit through laboratory tests, enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be near a target temperature Ttarget, maintains the temperature of a Die or Chip to be near the target temperature Ttarget during production, measures the reference voltage Vref output by the triode circuit, and determines a corresponding slope by searching the mapping table; the detected slope is set as the slope used in correction of each Die or Chip, and the whole method is simple and easy to realize.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are to be protected by the present invention.
Claims (4)
1. The temperature sensor correction method comprises a triode circuit, a sigma-delta modulator, a digital filter and a calibrator which are sequentially connected, wherein the triode circuit outputs zero temperature coefficient band gap reference voltage Vref and thermal voltage delta Vbe which is proportional to absolute temperature to the sigma-delta modulator, the digital filter outputs data Dout to the calibrator for calibration, and the calibrator calibrates the data Dout based on a set slope to obtain calibration data Dfinal, and the method is characterized by comprising the following steps:
determining a mapping table of a reference voltage Vref and a slope by laboratory testing for a determination process;
determining a trimming value Vref_trim of a reference voltage Vref of the triode circuit through laboratory test, wherein the trimming value Vref_trim enables a zero temperature coefficient point of the reference voltage Vref to be trimmed to be close to a target temperature Ttarget;
during production, the temperature of Die or Chip is maintained near the target temperature Ttarget, the reference voltage Vref output by a triode circuit is measured, and the corresponding slope is determined by searching the mapping table;
setting the detected slope as the slope used by each Die or Chip for correction;
the zero temperature coefficient point is determined in the following manner: changing the temperature of a temperature sensor, measuring a reference voltage Vref output by a triode circuit, and manufacturing a relation curve of Vref and the temperature by taking the temperature as an abscissa and taking the measured reference voltage Vref as an ordinate, wherein an extreme point of the relation curve of Vref and the temperature is the zero temperature coefficient point;
wherein, the look-up table of reference voltage Vref and slope is determined in advance through laboratory test, includes: setting the temperature of a temperature sensor as a target temperature Ttarget, sequentially adding different reference voltages Vref to the sigma-delta modulator, measuring data Dout output by the digital filter, manufacturing straight lines corresponding to the different reference voltages Vref when the absolute temperature is taken as an abscissa and the data Dout is taken as an ordinate, and determining the slope of each straight line to obtain a mapping table of the reference voltages Vref and the slope.
2. The method of claim 1, wherein the vicinity of the target temperature Ttarget is a temperature zone centered around the target temperature Ttarget.
3. A temperature sensor, characterized by comprising a triode circuit, a sigma-delta modulator, a digital filter and a calibrator which are connected in sequence, wherein the temperature sensor is corrected by adopting the method based on any one of claims 1-2 in the production process of the sensor.
4. A temperature sensor according to claim 3, wherein the calibrator calibrates the data Dout based on the following calculation formula: 。
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| CN111381623A (en) * | 2018-12-29 | 2020-07-07 | 无锡华润矽科微电子有限公司 | System for reference voltage trimming and corresponding reference voltage trimming method |
| CN112965565A (en) * | 2021-02-08 | 2021-06-15 | 苏州领慧立芯科技有限公司 | Band gap reference circuit with low temperature drift |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US11320322B2 (en) * | 2019-04-09 | 2022-05-03 | Winbond Electronics Corp. | Temperature sensor evaluation method |
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|---|---|---|---|---|
| CN1864116A (en) * | 2003-10-07 | 2006-11-15 | 阿纳洛格装置公司 | Method and apparatus for compensating for temperature drift in semiconductor processes and circuitry |
| JP2006119008A (en) * | 2004-10-22 | 2006-05-11 | Seiko Epson Corp | Temperature characteristic adjusting method of gyroscopic sensor, and gyroscopic sensor |
| CN102116687A (en) * | 2010-01-05 | 2011-07-06 | 上海华虹Nec电子有限公司 | Method for calibrating temperature precision of temperature sensor chip |
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