CN107490438B - Sensor circuit and method of use - Google Patents
Sensor circuit and method of use Download PDFInfo
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- CN107490438B CN107490438B CN201610407441.2A CN201610407441A CN107490438B CN 107490438 B CN107490438 B CN 107490438B CN 201610407441 A CN201610407441 A CN 201610407441A CN 107490438 B CN107490438 B CN 107490438B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/20—Compensating for effects of temperature changes other than those to be measured, e.g. changes in ambient temperature
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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
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Abstract
The invention provides a sensor circuit and a use method thereof, wherein the sensor circuit comprises: an operational amplifier comprising a first input terminal, a second input terminal, and an operational amplifier output terminal; the input module comprises a first connecting end and a second connecting end, the first connecting end is connected with a signal input, the second connecting end is connected with the first input end, the input module comprises an adjusting circuit, and the adjusting circuit is used for adjusting the impedance value of the input module; the feedback module comprises a third connecting end and a fourth connecting end, the third connecting end is connected with the first input end, the fourth connecting end is connected with the output end, and the feedback module comprises feedback impedance. The sensor circuit can improve the measurement precision and reduce the measurement error.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to a sensor circuit and a using method thereof.
Background
The temperature sensor is a module for determining the current ambient temperature by measuring the output code value. The coded value is obtained by converting the voltage value through an Analog to Digital Converter (ADC). The temperature sensor includes: a temperature converter for generating a voltage signal varying with temperature; a switched capacitor amplifier for amplifying an input voltage signal; and the analog-to-digital conversion module is used for converting the amplified voltage signal into an encoding value.
In the working process of the temperature sensor, the sensing module converts the ambient temperature into a voltage signal, the voltage signal is amplified by the switched capacitor amplifier, and the voltage signal is converted into an encoding value by the analog-to-digital conversion module at the later stage. The performance of the switched capacitor amplifier has an important influence on the measurement accuracy of the temperature sensor. With the development of semiconductor technology, high speed and high precision have been targets for designing temperature sensors. Therefore, a high-speed and high-precision switched capacitor amplifier is important.
However, the change of the process corner, the layout design and other factors can cause the voltage offset value of the sensing module, the voltage offset value cannot be avoided, and the precision of the conventional switched capacitor amplifier is low, so that the conventional temperature sensor has the defects of large measurement error and low measurement precision.
Disclosure of Invention
The invention aims to provide a sensor circuit and a using method thereof, which can reduce the measurement error of a sensor and improve the measurement precision.
To solve the above problems, the present invention provides a sensor circuit including: an operational amplifier comprising a first input terminal, a second input terminal, and an operational amplifier output terminal; the input module comprises a first connecting end and a second connecting end, the first connecting end is connected with the input signal, the second connecting end is connected with the first input end, and the input module comprises a regulating circuit which is used for regulating the impedance value of the input module; the feedback module comprises a third connecting end and a fourth connecting end, the third connecting end is connected with the first input end, the fourth connecting end is connected with the output end, and the feedback module comprises feedback impedance.
Optionally, the adjusting circuit includes: a first tuning impedance and a first switching device, the first tuning impedance and the first switching device being connected in series.
Optionally, the first switching device is a MOS transistor.
Optionally, the first adjusting impedance comprises a capacitance.
Optionally, the feedback impedance comprises a capacitance.
Optionally, the input module includes 1-7 adjusting circuits.
Optionally, the first input terminal is an inverting input terminal of the operational amplifier; the second input end is a positive input end of the operational amplifier.
Optionally, the adjusting circuit includes a first adjusting unit, a second adjusting unit, and a third adjusting unit; the first adjusting unit comprises a first adjusting impedance and a first switching device; the second adjusting unit comprises a second adjusting impedance and a second switching device; the third adjusting unit comprises a third adjusting impedance and a third switching device; the input impedance, the first adjusting impedance, the second adjusting impedance and the third adjusting impedance are capacitors.
Optionally, a ratio of the second adjusting impedance to the capacitance of the first adjusting impedance is: 1.8-2.2; the ratio of the third adjusting impedance to the capacitance of the first adjusting impedance is 3.6 to 4.4.
Optionally, the sensor circuit further comprises: a digital logic module comprising a switch control circuit for controlling the conditioning circuit; a temperature converter to convert a temperature signal to the input signal.
Optionally, the input module further includes an input circuit, the input circuit includes an input impedance, and the input impedance includes a capacitor.
Correspondingly, the invention also provides a use method of the sensor circuit, which comprises the following steps: providing a sensor circuit; adjusting the adjusting circuit to obtain the measurement error of the sensor circuit at a given temperature; obtaining circuit information when the measurement error is minimum; after the adjusting circuit is adjusted through the circuit information, the temperature of the surrounding environment is measured through the sensor circuit, and a measured value is output.
Optionally, the step of obtaining the measurement error includes: setting an ideal resulting temperature profile for the sensor circuit; adjusting the adjusting circuit to obtain the temperature curves of the measuring results of the adjusting circuit in different states; and comparing the ideal result temperature curve with the measurement result temperature curve to obtain a measurement error.
Optionally, the adjusting circuit includes: a first regulating impedance and a first switching device; the first switching device is an MOS tube; the step of adjusting the adjustment circuit comprises: and controlling the on and off of the first switching device by adjusting the grid voltage of the MOS tube.
Optionally, the method further includes: a digital logic circuit comprising a switch control circuit; the step of adjusting the first switching device comprises: and the grid voltage of the MOS tube is regulated by the switch control circuit.
Optionally, the adjusting circuit comprises one or more adjusting units; the adjusting unit includes: adjusting impedance and switching devices; the step of adjusting the adjustment circuit comprises: and adjusting the switching state of one or more switching devices to enable the adjusting circuit to be in different states.
Compared with the prior art, the technical scheme of the invention has the following advantages:
in the sensor circuit of the present invention, the input module circuit includes an adjustment circuit that can adjust an impedance value of the input module, thereby adjusting a measurement result of the sensor circuit. Specifically, before the sensor circuit is applied, the impedance value of the input module may be adjusted by the adjusting circuit, so as to adjust the amplification factor of the operational amplifier, further make the measurement result of the sensor circuit closer to an actual value, and reduce the measurement error of the sensor circuit caused by the voltage deviation input to the first connection terminal. Therefore, the sensor circuit can improve the measurement precision and reduce the measurement error.
In the use method of the sensor circuit, before the temperature of the surrounding environment is measured, the adjusting circuit is adjusted to obtain the measurement error of the sensor circuit at the given temperature, so that the adjusting circuit of the sensor circuit is in the state of the minimum measurement error, the measurement result of the sensor circuit is closer to the actual value, and the measurement error caused by the voltage deviation input into the first connecting end is further reduced. Therefore, the use method of the temperature amplifier can improve the measurement accuracy of the sensor circuit and reduce the measurement error.
Drawings
FIG. 1 is a schematic diagram of a temperature sensor;
FIG. 2 is a schematic diagram of a switched capacitor amplifier circuit;
FIGS. 3 and 4 are schematic structural diagrams of an embodiment of a sensor circuit of the present invention;
FIG. 5 is a graph comparing temperature measured with different sensor circuits versus measurement error.
Detailed Description
Temperature sensors have a number of problems, for example: the measurement error is large, and the measurement precision is low.
Now, a temperature sensor is combined, and the reasons that the measurement error of the temperature sensor is large and the measurement precision is low are analyzed:
FIG. 1 is a schematic diagram of a temperature sensor; fig. 2 is a schematic diagram of a switched capacitor amplifier circuit in the sensing module 21 shown in fig. 1.
Referring to fig. 1, the temperature sensor includes: a sensing module 21 and an analog-to-digital conversion module 22.
The sensing module 21 comprises a temperature converter for converting a temperature signal into a voltage signal V0. The sensing module 21 further comprises a switched capacitor amplifier circuit.
Referring to fig. 2, the switched capacitor amplifier circuit includes:
an operational amplifier 100, said operational amplifier 100 comprising: a positive input 112, a negative input 111, and an output 120;
a first capacitor C11Said first capacitor C11The operational amplifier 100 comprises a first capacitor input end and a first capacitor output end, wherein the first capacitor output end is connected with a negative input end 111 of the operational amplifier 100;
first switch S11Said first switch S11The method comprises the following steps: a first switch input 11 and a first switch outputThe first switch output end is connected with the first capacitor input end, and the first switch input end 11 is used for inputting an input signal;
second capacitor C12Said second capacitor C12The first capacitor input end is connected with the negative input end 111, and the second capacitor output end is connected with the operational amplifier output end 120;
a second switch S12Said second switch S12And the second capacitor C12And (4) connecting in parallel.
The analog-to-digital conversion module 22 (shown in fig. 1) is coupled to the output 120.
When the temperature sensor works, the temperature converter in the sensing module 21 outputs a voltage V which changes with the temperature0Said voltage V being0The first switch input 11 and the positive input 112. The voltage V0An amplified voltage V is output through the operational amplifier 100.
However, due to the influence of factors such as the design of the sensor circuit process corner circuit, the actual voltage V0 input to the first switch input terminal 11 and the forward input terminal 112 is often different from the ideal voltage, and the amplification factor of the operational amplifier is also often different from the ideal amplification factor, which easily causes the output amplified voltage V to be different from the ideal amplified voltage, so that after the amplified voltage V is processed by the subsequent circuit, the output test result is easily deviated from the actual test result, thereby causing the problem of large error of the measurement result of the temperature amplifier and low test accuracy.
With continued reference to fig. 1, to address the above problem, one approach is to connect a calibration module 23 after the analog-to-digital conversion module 22. The voltage V which is output by the sensing module 21 and changes with the temperature outputs an encoding value C through the analog-to-digital conversion module 22. Due to the influence of process corners and layout design factors, the voltage V has deviation from the ideal voltage, so that the code value C has deviation from the ideal code value. The calibration module 23 assumes the offset to be a fixed value and sets an offset value according to the fixed value. During calibration, the calibration module 23 adds or subtracts the deviation value based on the code value C, thereby reducing the measurement error of the temperature sensor.
However, since the deviation between the code value C and the ideal code value is not a fixed value at different temperatures, the calibration module 23 assumes that the deviation is a fixed value. Therefore, the temperature sensor still has the defects of large measurement error and low precision.
In order to solve the above problem, the present invention provides a sensor circuit including: an operational amplifier comprising a first input terminal, a second input terminal, and an operational amplifier output terminal; the input module comprises a first connecting end and a second connecting end, the first connecting end is connected with the input signal, the second connecting end is connected with the first input end, and the input module comprises a regulating circuit which is used for regulating the impedance value of the input module; the feedback module comprises a third connecting end and a fourth connecting end, the third connecting end is connected with the first input end, the fourth connecting end is connected with the output end, and the feedback module comprises feedback impedance.
Wherein the input module comprises an adjustment circuit capable of adjusting an impedance value of the input module to adjust a measurement result of the sensor circuit. Specifically, before the sensor circuit is applied, the impedance value of the input module can be adjusted by the adjusting circuit, so that the amplification factor of the operational amplifier is adjusted, the measurement result of the sensor circuit is closer to an actual value, and the measurement error of the sensor circuit caused by the voltage deviation input into the input module is reduced. Therefore, the sensor circuit can improve the measurement precision and reduce the measurement error.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 3 and 4 are schematic structural diagrams of an embodiment of the sensor circuit of the present invention.
Referring to fig. 3, the sensor circuit includes: a sensing module 210 for measuring the signal T of the temperature to be measured0Is converted into an output voltage Vout(ii) a An analog-to-digital conversion module 220 for inputting the output voltage VoutAnd the output voltage V is adjustedoutConverting the Code into a Code value; and the digital logic module 230 is configured to input the Code value, compare the Code value, set the adjusting circuit in the sensing module 210 according to a comparison result, and output a final Code value.
In this embodiment, the sensing module 210 includes a temperature converter for converting the input temperature signal T0Converted into a voltage signal.
In this embodiment, the analog-to-digital conversion module 220 is configured to convert the voltage into a Code value. In order to provide sufficient accuracy of the output result of the analog-to-digital conversion module, the sensing module 210 further includes an amplifier for amplifying the voltage signal. The accuracy of the amplifier and the circuit design of the sensor have a significant impact on the test results of the sensor circuit. The amplifier of the sensor circuit includes:
referring to fig. 4, an operational amplifier 200, the operational amplifier 200 includes a first input terminal 211, a second input terminal 212, and an operational amplifier output terminal 220.
In this embodiment, the operational amplifier 200 is used to implement the operation on the input signal.
In this embodiment, the first input terminal 211 is an inverting input terminal of the operational amplifier 200; the second input 212 is the same-direction input of the operational amplifier 200.
With continued reference to fig. 4, the input module 250 includes a first connection end 241 and a second connection end, the first connection end 241 is used for inputting an input signal, the second connection end is connected to the first input end 211, and the input module 250 includes an adjusting circuit, and the adjusting circuit is used for adjusting an impedance value of the input module. The input module is used for adjusting the amplification factor of the amplifier,
the input module further comprises: the input circuit is used for controlling the amplification factor of the amplifier, and the adjusting circuit is used for adjusting the amplification factor of the amplifier.
In this embodiment, the adjusting circuit includes: the device comprises a first adjusting unit, a second adjusting unit and a third adjusting unit. In other embodiments, the input module may further include a plurality of the adjusting circuits.
The first adjusting unit, the second adjusting unit and the third adjusting unit are used for adjusting the amplification factor of the amplifier.
In this embodiment, the input circuit, the first adjusting unit, the second adjusting unit, and the third adjusting unit are connected in parallel, and in other embodiments, the first adjusting unit, the second adjusting unit, and the third adjusting unit may also be connected in series.
In this embodiment, the input circuit includes: input impedance Z0(ii) a The first adjusting unit comprises a first adjusting impedance Z1And a first switching device S1(ii) a The second adjusting unit comprises a second adjusting impedance Z2And a second switching device S2(ii) a The third adjusting unit comprises a third adjusting impedance Z3And a third switching device S3。
In this embodiment, the switching amplifier further includes an input switch S0Said input switch S0And is connected in series with the input module 250, and is used for controlling the amplification factor of the amplifier together with the first switching device, the second switching device and the third switching device.
In this embodiment, the input circuit, the first adjusting unit, the second adjusting unit and the third adjusting unit are connected in parallel, so that the first adjusting impedance Z is obtained1And a first switching device S1Are connected in series; second adjusted impedance Z2And a second switching device S2Are connected in series; third adjusted impedance Z3And a third switching device S3Are connected in series. In other embodiments, the first adjusting unit, the second adjusting unit and the third adjusting unit are connected in series, and then the first adjusting impedance and the first switching device are connected in parallel; a second adjusted impedance andthe second switching devices are connected in parallel; the third adjusting impedance is connected in parallel with the third switching device.
In this embodiment, the input impedance Z0A first adjusting impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3Is a capacitor.
In this embodiment, the first switch S1A second switch S2And a third switch S3Is a MOS transistor. The on and off of the MOS transistor can be controlled by adjusting the grid voltage, so that the first adjusting unit, the second adjusting unit and the third adjusting unit are switched on and off.
In this embodiment, the input module 250 has an input capacitance C, and the input capacitance C is provided by the first switch S1A second switch S2And a third switch S3The off and on states of the switch. The first switch S1A second switch S2And a third switch S3Respectively determine a first adjusted impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3Whether a circuit is connected or not is determined, so that the impedance value of the input module 250 is determined. Thus, the first switch S can be adjusted1A second switch S2And a third switch S3The off and on states of (a) adjust the amplification of the amplifier.
With continued reference to fig. 4, the feedback module 240 includes a third connection terminal and a fourth connection terminal, the third connection terminal is connected to the first input terminal 211, the fourth connection terminal is connected to the operational amplifier output terminal 220, and the feedback module 240 includes a feedback impedance Z4。
The feedback module 240 and the input module 250 together determine the amplification of the amplifier.
In this embodiment, the feedback module 240 further includes a feedback impedance Z4Parallel feedback switch S4。
In this embodiment, the feedback module 240 includes only one feedback impedance Z4Said feedback impedance Z4Being a capacitor, the feedback impedance Z4Has a capacitance value of C4Said feedback impedance Z4Capacitance value C of4I.e., the feedback capacitance value of the feedback module 240.
In other embodiments, the feedback module may further include a plurality of feedback impedances, and the plurality of feedback impedances are connected in parallel or in series to jointly determine the impedance value of the feedback module.
In this embodiment, the amplification factor a of the amplifier is determined by the input capacitor C of the input module 250 and the feedback capacitance value of the feedback module 240. Specifically, the expression of the magnification factor a is: a ═ C/C4。
In this embodiment, the input capacitance C is equal to the sum of the capacitances of the switched-on input impedances, and accordingly, it can be obtained that the adjusting circuit is in different states and the amplification factor of the amplifier.
In particular, if the input impedance Z0Is switched on, the first adjusted impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3All are disconnected, the magnification is: a ═ C0/C4；
If the input impedance Z0And the first adjusting impedance Z1Switched on, second adjusted impedance Z2And a third adjusted impedance Z3All are disconnected, the magnification is: a ═ C0+C1)/C4；
If the input impedance Z0And a second adjusted impedance Z2Is switched on, the first adjusted impedance Z1And a third adjusted impedance Z3All are disconnected, the magnification is: a ═ C0+C2)/C4；
If the input impedance Z0And a third adjusted impedance Z3Is switched on, the first adjusted impedance Z1And a second adjusted impedance Z2All are disconnected, the magnification is: a ═ C0+C3)/C4；
If the input impedance Z0The first adjusting impedance Z1And a second adjusted impedance Z2Switch on, the third adjusted impedanceZ3All are disconnected, the magnification is: a ═ C0+C1+C2)/C4；
If the input impedance Z0The first adjusted impedance Z1And a third adjusted impedance Z3Switched on, second adjusted impedance Z2All are disconnected, the magnification is: a ═ C0+C1+C3)/C4；
If the input impedance Z0The second adjusted impedance Z2And a third adjusted impedance Z3Switched on, first adjusted impedance Z1All are disconnected, the magnification is: a ═ C0+C2+C3)/C4。
If the input impedance Z0The first adjusting impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3Are both on, the magnification is: a ═ C0+C1+C2+C3)/C4。
Wherein, C0Is an input impedance Z0The capacitance value of (a); c1For first adjustment of impedance Z1The capacitance value of (a); c2For second adjustment of impedance Z2The capacitance value of (a); c3For third adjustment of impedance Z3The capacitance value of (2).
By analogy, the amplification factor a of the amplifier can have 8 values, and the first switch S can be selected according to actual conditions1A second switch S2And a third switch S3Thereby adjusting the amplification factor of the amplifier and improving the measurement accuracy of the sensor circuit. The larger the number of the adjusting circuits included in the amplifier is, the more the amplification factor of the amplifier is selected, which is more beneficial to expanding the measuring range of the sensor circuit.
If, C1<C2<C3，C2/C1Or C3/C2The value of (A) is too small, the range of the amplification factor of the amplifier is easy to reduce, and therefore the temperature range accurately measured by the sensor circuit is reduced; if C is present2/C1Or C3/C2Value of (2)Large, it is easy to lower the adjustment accuracy of the amplifier, thereby reducing the measurement accuracy of the sensor circuit. In this embodiment, a ratio of the second adjusting impedance to the capacitance of the first adjusting impedance is: 1.8-2.2; the ratio of the third adjusting impedance to the capacitance of the first adjusting impedance is 3.6 to 4.4.
The accuracy of the sensor circuit is set by C1/C0、(C2-C1)/C0、(C3-C2)/C0Etc. is determined. In this example, C1:C2:C31:2:4, i.e. the accuracy of the sensor circuit is given by C1/C0Determination of the value of C1/C0The smaller the value of (c), the higher the accuracy of the sensor circuit.
Specifically, in this embodiment, the input impedance Z is0Capacitor C of010PF to 14 PF; the first adjusted impedance Z1Capacitor C of1Is 22fF to 28 fF; the second adjusted impedance Z2Capacitor C of244fF to 56 fF; the third adjusted impedance Z3Capacitor C of388fF to 112 fF.
Referring to fig. 3 and 4 in combination, in the present embodiment, the input voltage V input to the amplifier0Is amplified to an output voltage V by the amplifierout，Vout＝A*V0. The output voltage VoutAnd the Code is converted into a Code value through an analog-to-digital conversion module of a later stage.
It should be noted that the sensor circuit includes a digital logic module 230, and the digital logic module 230 processes the Code value output by the analog-to-digital conversion module 220 to output a measurement result. In this embodiment, the digital logic module 230 further includes a switch control circuit, and the switch control circuit is used to control the first switch S1A second switch S2And a third switch S3To control the first regulating impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3To adjust the amplification a of the amplifier. Due to the fact thatThis enables the measurement result to be adjusted, thereby improving the measurement accuracy of the sensor circuit.
In summary, in the sensor circuit of the present invention, the input module circuit includes an adjusting circuit, and the adjusting circuit can adjust the impedance value of the input module, so as to adjust the measurement result of the sensor circuit. Specifically, before the sensor circuit is applied, the impedance value of the output module is adjusted by the adjusting circuit, so that the amplification factor of the operational amplifier is adjusted, the measurement result of the sensor circuit is closer to an actual value, and the measurement error of the sensor circuit caused by the voltage deviation input to the first connection terminal is reduced. Therefore, the sensor circuit can improve the measurement precision and reduce the measurement error.
Referring to fig. 3 to fig. 5, an embodiment of a method for using a sensor circuit according to the present invention includes:
providing a sensor circuit, the sensor circuit comprising: an operational amplifier 200, the operational amplifier 200 comprising a first input 211, a second input 212, and an operational amplifier output 220; the input module 250 includes a first connection end and a second connection end, the first connection end is connected to input signals, the second connection end is connected to the first input end 211, the input module 250 includes an input circuit and an adjustment circuit, and the adjustment circuit is used to adjust an impedance value of the input module 250; a feedback module 240, wherein the feedback module 240 includes a third connection terminal and a fourth connection terminal, the third connection terminal is connected to the first input terminal 211, the fourth connection terminal is connected to the operational amplifier output terminal 220, and the feedback module 240 includes a feedback impedance Z4(ii) a Adjusting the adjusting circuit to obtain the measurement error of the sensor circuit at a given temperature; placing the regulating circuit in a state where the measurement error is minimal; and measuring the temperature of the surrounding environment through the sensor circuit, and outputting a measurement result T.
Referring to fig. 3 and 4, a sensor circuit is provided. The sensor circuit includes:
in this embodiment, the structure of the sensor circuit is the same as that of the previous embodiment and is not described herein again.
With continued reference to fig. 3 and 4, the adjustment circuit is adjusted to obtain the measurement error of the sensor circuit at a given temperature.
The regulating circuit comprises one or more regulating units; the adjusting unit includes: adjusting impedance and switching devices; the step of adjusting the adjustment circuit comprises: and adjusting the switching state of one or more switching devices to enable the adjusting circuit to be in different states.
In this embodiment, the adjusting circuit includes three adjusting units, which are respectively: the device comprises a first adjusting unit, a second adjusting unit and a third adjusting unit.
In this embodiment, the first switch S is controlled by the switch control circuit in the digital logic module 2301A second switch S2And a third switch S3The off and on states of the amplifier are controlled, so that the amplification factor of the amplifier is adjusted, and the test result of the sensor circuit is adjusted.
In this embodiment, the first switch S1A second switch S2And a third switch S3All MOS tubes are used, therefore, the grid voltage of the MOS tubes can be adjusted to the first switch S through the switch control circuit1A second switch S2And a third switch S3The switching state of (a) is adjusted.
Specifically, in this embodiment, the output voltage V of the amplifierout＝A*V0Wherein, in the step (A),
when the input impedance Z0Is switched on, the first adjusted impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3When all are disconnected, the amplification factor is as follows: a ═ C0/C4；
When the input impedance Z0And the first adjusting impedance Z1Switched on, second adjusted impedance Z2And a third adjusted impedance Z3When all are disconnected, the amplification factor is as follows: a ═ C0+C1)/C4；
When the input impedance Z0And a second adjusted impedance Z2Is switched on, the first adjusted impedance Z1And a third adjusted impedance Z3When all are disconnected, the amplification factor is as follows: a ═ C0+C2)/C4；
When the input impedance Z0And a third adjusted impedance Z3Is switched on, the first adjusted impedance Z1And a second adjusted impedance Z2When all are disconnected, the amplification factor is as follows: a ═ C0+C3)/C4；
When the input impedance Z0The first adjusting impedance Z1And a second adjusted impedance Z2Switch on, the third adjusted impedance Z3When all are disconnected, the amplification factor is as follows: a ═ C0+C1+C2)/C4；
When the input impedance Z0The first adjusting impedance Z1And a third adjusted impedance Z3Switched on, second adjusted impedance Z2When all are disconnected, the amplification factor is as follows: a ═ C0+C1+C3)/C4。
When the input impedance Z0The second adjusted impedance Z2And a third adjusted impedance Z3Switched on, first adjusted impedance Z1When all are disconnected, the amplification factor is as follows: a ═ C0+C2+C3)/C4。
When the input impedance Z0The first adjusting impedance Z1A second adjusted impedance Z2And a third adjusted impedance Z3When both are on, the magnification is: a ═ C0+C1+C2+C3)/C4。
It can be seen that, in the present embodiment, the switch control circuit can control the first switch S1A second switch S2And a third switch S3The control of the off and on states of the amplifier realizes the adjustment of the amplification factor of the amplifier.
In this embodiment, the output voltage VoutAnd then converted into Code value through the analog-to-digital conversion module of the later stage,the Code value Code and the output voltage VoutIn a direct proportion relation, the proportionality coefficient is k. In particular, the Code value Code is kVout。
The Code value is input to the digital logic module 230, the digital logic module 230 compares the Code value, the adjusting circuit is set according to the comparison result, the Code value with the minimum error is obtained, and the final Code value is output.
In this embodiment, the final coded value is further subjected to a series of numerical calculations to obtain a test result T, where T is kVout+ m; thus obtaining T-kAV0+m。
It should be noted that if the voltage V is influenced by factors such as process corner or layout design0And an ideal input voltage V1In contrast, in an ideal situation, the measurement result of the sensor circuit is: t is1＝kA1V1+ m wherein A1Is the ideal amplification factor of the amplifier.
From the above analysis, it can be seen that the amplifier can be adjusted so that the amplification of the amplifier satisfies AV0Is as much as possible equal to A1V1Then the measurement result T0And ideal measurement result T1The deviation of (a) can be compensated by the amplification of the amplifier.
Therefore, in this embodiment, the step of acquiring the measurement error of the sensor circuit at a given temperature includes: setting an ideal result temperature curve of the sensor circuit according to actual needs; adjusting the adjusting circuit to obtain temperature curves of measurement results in different switch states; and comparing the ideal result temperature curve with the measurement result temperature curve to obtain a measurement error.
Specifically, the measurement results T of the 8 switch states are measured at one or more preset temperatures0Processing to obtain 8 measurement results T0Discrete relation with preset temperature and ideal test result T under ideal state1Comparing and analyzing the discrete relation with the preset temperature to obtain the measurement error and obtain the switch state which minimizes the measurement error。
In this embodiment, the number of the preset temperatures is one, and the measurement error may be a measurement result T at a certain specified temperature0And ideal test result T1The difference of (a). Specifically, the preset temperature is room temperature (25 ℃). The measurement error refers to the measurement result T at room temperature (namely 25℃)0And ideal test result T1The difference of (a). In other embodiments, the preset temperature may be multiple, and the measurement error refers to a squared difference between a measurement result and an ideal test result at multiple preset temperatures.
In other embodiments, the step of acquiring a measurement error of the sensor circuit at a given temperature may further include: setting a preset encoding value temperature curve of the sensor circuit according to actual needs; adjusting the adjusting circuit to obtain the encoding value temperature curves under different switch states; and comparing the preset encoding value temperature curve with the encoding value temperature curves in different switch states to obtain a deviation error, wherein the deviation error is used as a measurement error.
The deviation error may be a difference between a Code value at a certain specified temperature and a preset Code value at the temperature, or may refer to a square difference between the Code value and the preset Code value at a plurality of preset temperatures. In other embodiments, the deviation error may be analyzed as a measurement error for the state of the regulating circuit.
Referring to fig. 3 and 4, the circuit information with the minimum measurement error is obtained.
In this embodiment, the first switch S is controlled by the switch control circuit1A second switch S2And a third switch S3Is turned on or off, thereby making the first switch S1A second switch S2And a third switch S3And the state of the measurement error is minimum.
Referring to fig. 5, after the adjusting circuit is adjusted by the circuit information, the temperature of the surrounding environment is measured by the sensor circuit, and the measurement result is output.
In this embodiment, the adjustment circuit is in a state where the measurement error is minimized at room temperature. And measures the temperature of the surrounding environment in this state.
Fig. 5 shows a comparison of the temperature measured with different sensor circuits versus the measurement error. The abscissa represents the test temperature; the ordinate indicates the measurement error at the corresponding temperature. The measurement error refers to a difference between a measurement result and an ideal result.
As can be seen from FIG. 5, the maximum value of the measurement error obtained by the method of using the sensor circuit of the present invention is about-0.5 ℃ in the temperature range of-40 ℃ to 125 ℃; the maximum value of the measurement error obtained by the sensor circuit including only the input circuit is about-2.1 c in the temperature range of-40 c to 125 c. Therefore, the use method of the sensor circuit can reduce the measurement error and improve the measurement precision.
In summary, in the method for using the sensor circuit of the present invention, before measuring the temperature of the surrounding environment, the adjustment circuit is adjusted to obtain the measurement error of the sensor circuit at a given temperature, so that the adjustment circuit of the sensor circuit is in a state of minimum measurement error, thereby enabling the measurement result of the sensor circuit to be closer to an actual value, and further reducing the measurement error caused by the voltage deviation input to the adjustment circuit. Therefore, the use method of the temperature amplifier can improve the measurement accuracy of the sensor circuit and reduce the measurement error.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (12)
1. A sensor circuit, comprising: an amplifier, the amplifier comprising: the operational amplifier, the input module and the feedback module; the amplifier is used for amplifying the voltage signal;
the operational amplifier comprises a first input end, a second input end and an operational amplifier output end;
the input module comprises a first connecting end and a second connecting end, wherein the first connecting end is used for inputting an input signal, the second connecting end is connected with the first input end, and the input module comprises an input circuit and an adjusting circuit, wherein the input circuit is used for controlling the amplification factor of the amplifier; the adjusting circuit comprises a first adjusting unit, a second adjusting unit and a third adjusting unit; the first adjusting unit, the second adjusting unit and the third adjusting unit are used for adjusting the amplification factor of the amplifier, wherein the input circuit, the first adjusting unit, the second adjusting unit and the third adjusting unit are connected in parallel;
the feedback module comprises a third connecting end and a fourth connecting end, the third connecting end is connected with the first input end, the fourth connecting end is connected with the output end, and the feedback module comprises feedback impedance;
the first adjusting unit comprises a first adjusting impedance and a first switching device;
the second adjusting unit comprises a second adjusting impedance and a second switching device;
the third adjusting unit comprises a third adjusting impedance and a third switching device;
the first adjusting impedance, the second adjusting impedance and the third adjusting impedance are capacitors, and the ratio of the second adjusting impedance to the capacitors of the first adjusting impedance is 1.8-2.2; the ratio of the capacitance of the third adjusting impedance to the capacitance of the first adjusting impedance is 3.6-4.4.
2. The sensor circuit of claim 1, wherein the first switching device is a MOS transistor.
3. The sensor circuit of claim 1, wherein the feedback impedance comprises a capacitance.
4. The sensor circuit of claim 1, wherein the input module includes 1-7 conditioning circuits.
5. The sensor circuit of claim 1, wherein the first input is an inverting input of the operational amplifier; the second input terminal is a positive input terminal of the operational amplifier.
6. The sensor circuit of claim 1, further comprising: a digital logic module comprising a switch control circuit for controlling the conditioning circuit;
a temperature converter to convert a temperature signal to the input signal.
7. The sensor circuit of claim 1, wherein the input module further comprises an input circuit comprising an input impedance, the input impedance comprising a capacitance.
8. A method of using a sensor circuit, comprising:
providing a sensor circuit according to any one of claims 1 to 7;
adjusting the adjusting circuit to obtain the measurement error of the sensor circuit at a given temperature;
obtaining circuit information when the measurement error is minimum;
after the adjusting circuit is adjusted through the circuit information, the temperature of the surrounding environment is measured through the sensor circuit, and a measured value is output.
9. The method of using a sensor circuit of claim 8, wherein the step of obtaining a measurement error comprises: setting an ideal resulting temperature profile for the sensor circuit;
adjusting the adjusting circuit to obtain the temperature curves of the measuring results of the adjusting circuit in different states;
and comparing the ideal result temperature curve with the measurement result temperature curve to obtain a measurement error.
10. The method of using a sensor circuit of claim 8, wherein the conditioning circuit comprises: a first regulating impedance and a first switching device; the first switching device is an MOS tube;
the step of adjusting the first switching device comprises: and controlling the on and off of the first switching device by adjusting the grid voltage of the MOS tube.
11. The method of using a sensor circuit of claim 10, wherein the sensor circuit further comprises: a digital logic circuit comprising a switch control circuit;
the step of adjusting the first switching device comprises: and the grid voltage of the MOS tube is regulated by the switch control circuit.
12. The method of using a sensor circuit of claim 8, wherein the conditioning circuit comprises a plurality of conditioning units; the adjusting unit includes: adjusting impedance and switching devices;
the step of adjusting the adjustment circuit comprises: and adjusting the switching state of one or more switching devices to enable the adjusting circuit to be in different states.
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| CN201610407441.2A CN107490438B (en) | 2016-06-12 | 2016-06-12 | Sensor circuit and method of use |
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| CN113125920B (en) * | 2019-12-27 | 2024-03-22 | 中芯国际集成电路制造(上海)有限公司 | Process sensor |
| CN113551693A (en) * | 2021-07-26 | 2021-10-26 | 联合微电子中心有限责任公司 | Step-by-step self-zero-adjusting detection circuit and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE19651922C2 (en) * | 1996-12-13 | 2001-11-15 | Stn Atlas Elektronik Gmbh | Matching amplifier for an induction probe and measuring device with at least two induction probes arranged at a distance from one another |
| JP4342613B2 (en) * | 1998-06-19 | 2009-10-14 | 旭化成エレクトロニクス株式会社 | Switched capacitor circuit |
| US6545534B1 (en) * | 2001-02-13 | 2003-04-08 | Analog Devices, Inc. | Low voltage variable gain amplifier with constant input impedance and adjustable one-pole filtering characteristic |
| CN100386964C (en) * | 2005-03-04 | 2008-05-07 | 清华大学 | Amplifier of power supply by AC power supply in switch condenser circuit |
| JP2007324696A (en) * | 2006-05-30 | 2007-12-13 | Toyota Motor Corp | Switched capacitor amplifier circuit |
| CN102435336B (en) * | 2011-10-11 | 2013-09-18 | 中国科学院半导体研究所 | Programmable CMOS (Complementary Metal Oxide Semiconductor) temperature sensor with double-precision working mode |
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