CN111707297B - Sensor compensation circuit - Google Patents
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- CN111707297B CN111707297B CN201910203096.4A CN201910203096A CN111707297B CN 111707297 B CN111707297 B CN 111707297B CN 201910203096 A CN201910203096 A CN 201910203096A CN 111707297 B CN111707297 B CN 111707297B
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- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
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Abstract
The invention relates to a sensor compensation circuit. The sensor compensation circuit compensates the offset by using a switching circuit, wherein two operation modes respectively generate two output voltages, the two output voltages are subtracted to eliminate the offset, and the offset is calculated by adding the two output voltages. And in addition, a noise threshold value is set for judging whether the circuit is interfered, when the addition result of the two output voltages is greater than the noise threshold value, the circuit is considered to be interfered, and the reserved output data cannot be updated. And designing a prompt signal to indicate that the circuit is interfered when the addition result of the two output voltages is greater than the noise threshold value. The circuit also comprises a display for displaying the output data, and when the addition result of the two output voltages is greater than the noise threshold value, the output data flickers to indicate that the circuit is interfered.
Description
Technical Field
The present invention relates to a sensor compensation circuit, and more particularly, to a bridge sensor having a compensation circuit for compensating an offset of a sensor or a circuit.
Background
Bridge sensors are widely used in various electronic components, such as pressure sensors, strain sensors, and gravity sensors, and typically utilize low noise amplifiers and analog-to-digital converters to convert voltage or current to a digital output. However, some non-ideal effects in the sensor circuit, such as leakage current of components and traces, and offset of the low noise amplifier and the analog-to-digital converter, affect the accuracy of the sensor.
Taiwan patent No. I515413 discloses a bridge sensor detection circuit, which includes an amplifying circuit, a charging/discharging unit and a processing unit. The processing unit controls the charging time and the discharging time of the charging and discharging unit, and calculates the output voltage according to a formula of charge balance, so that the precision of the bridge sensor is improved. However, the offset of the bridge sensor is not particularly detected and compensated, and the detection circuit also needs an accurate reference voltage and a timer to improve the accuracy.
In the invention patent of U.S. Pat. No. 9,726,705, an architecture is disclosed in which switching circuits are respectively added to two input voltage terminals of a bridge sensor. The operation method is to turn on one of the switches and turn off the other switch, and to perform two measurements, and to compare the output voltages of the two measurements to detect the leakage current effect. However, this is only an operation mode for detecting the leakage current, and the signals cannot be measured at the same time.
Disclosure of Invention
The invention provides a sensor compensation circuit, which comprises a sensor, four switches and an amplifier. The sensor includes a first input, a second input, a first output, and a second output. The first switch is connected between the first power supply terminal and the first input terminal, the second switch is connected between the first power supply terminal and the second input terminal, the third switch is connected between the second power supply terminal and the first input terminal, and the fourth switch is connected between the second power supply terminal and the second input terminal. The first output end and the second output end are respectively connected to the positive input end and the negative input end of the amplifier, and the voltage of the output end of the amplifier is multiplied by a gain according to the voltage difference between the positive input end and the negative input end of the amplifier.
The sensor compensation circuit described above is divided into two modes of operation: a first mode of operation and a second mode of operation. The first operation mode turns on the first switch and the fourth switch, turns off the second switch and the third switch, and connects the first power supply terminal to the first input terminal and the second power supply terminal to the second input terminal; the second operation mode turns on the second switch and the third switch, turns off the first switch and the fourth switch, and connects the first power supply terminal to the second input terminal and the second power supply terminal to the first input terminal. The voltage of the output end of the amplifier generated by the first operation mode and the voltage of the output end of the amplifier generated by the second operation mode are subtracted, so that the offset of the amplifier can be eliminated, and the leakage current caused by the routing between the sensor and the amplifier can be compensated. In addition, the magnitude of the offset may be calculated from the result of adding the voltages at the output terminals of the amplifier generated by the first and second operation modes.
The sensor compensation circuit further comprises an analog-to-digital converter for converting the voltage at the output end of the amplifier into digital data, and an operational circuit for operating the digital data generated in the first operation mode and the second operation mode, subtracting the voltage at the output end of the amplifier generated in the first operation mode and the second operation mode and dividing the subtracted voltage by 2, or generating output data according to the voltage at the output end of the amplifier generated in the first operation mode.
When the sensor or the compensation circuit is subjected to abnormal interference, such as shaking or noise interference, the addition result is larger than a normal value, and the output data is also influenced by the abnormal interference. Therefore, a noise threshold is additionally set, and if the addition result is greater than the noise threshold, the circuit is considered to be abnormally interfered, and the fixed output data is not updated.
In the sensor compensation circuit, the noise threshold is a fixed default value or a value derived based on an addition result of voltages at the output end of the amplifier generated in the first operation mode and the second operation mode.
The sensor compensation circuit further comprises a prompt signal, and when the addition result of the voltages of the output ends of the amplifiers generated in the first operation mode and the second operation mode is larger than the noise threshold value, the prompt signal is used for indicating that the circuit is in a disturbed state.
The sensor compensation circuit further comprises a display for displaying the output data. When the addition result of the voltages of the output ends of the amplifiers generated in the first operation mode and the second operation mode is larger than the noise threshold value, the output data displayed on the display flickers or other prompt signals are displayed to indicate that the circuit is in a disturbed state.
The invention provides another sensor compensation circuit, which comprises a sensor, four switching circuits and an amplifier. The sensor includes a first input, a second input, a first output and a second output. A first power supply terminal is connected to the first input terminal, and a second power supply terminal is connected to the second input terminal. The first switch is connected between the first output terminal and the positive amplifier input terminal, the second switch is connected between the first output terminal and the negative amplifier input terminal, the third switch is connected between the second output terminal and the positive amplifier input terminal, and the fourth switch is connected between the second output terminal and the negative amplifier input terminal. And the voltage at the output end of the amplifier is multiplied by a gain according to the voltage difference between the positive input end of the amplifier and the negative input end of the amplifier.
The sensor compensation circuit is divided into two operation modes; the first operation mode turns on the first switch and the fourth switch, turns off the second switch and the third switch, and enables the first output end to be connected to the positive amplifier input terminal and the second output end to be connected to the negative amplifier input terminal; the second operating mode turns on the second switch and the third switch, turns off the first switch and the fourth switch, and has the first output terminal connected to the negative terminal of the amplifier input and the second output terminal connected to the positive terminal of the amplifier input. The offset of the amplifier is eliminated by subtracting the voltages at the output of the amplifier resulting from the first and second modes of operation. In addition, the magnitude of the offset may be calculated from the result of adding the voltages at the output terminals of the amplifier generated by the first and second operation modes.
The sensor compensation circuit further comprises an analog-to-digital converter for converting the voltage at the output end of the amplifier into digital data, and an operational circuit for operating the digital data generated in the first operation mode and the second operation mode, subtracting the voltage at the output end of the amplifier generated in the first operation mode and the second operation mode and dividing the subtracted voltage by 2, or generating output data according to the voltage at the output end of the amplifier generated in the first operation mode.
When the sensor or the compensation circuit is subjected to abnormal interference, such as shaking or noise interference, the addition result is larger than a normal value, and the output data is also influenced by the abnormal interference. Therefore, a noise threshold is additionally set, and if the addition result is greater than the noise threshold, it is considered that the circuit is abnormally disturbed, and the fixed output data is not updated.
In the sensor compensation circuit, the noise threshold is a fixed default value or a value derived based on an addition result of voltages at the output end of the amplifier generated in the first operation mode and the second operation mode.
The sensor compensation circuit further comprises a prompt signal, and when the addition result of the voltages of the output ends of the amplifiers generated in the first operation mode and the second operation mode is larger than the noise threshold value, the prompt signal is used for indicating that the circuit is in a disturbed state.
The sensor compensation circuit further comprises a display for displaying the output data. When the addition result of the voltage of the output end of the amplifier generated in the first operation mode and the second operation mode is larger than the noise threshold value, the output data displayed on the display flickers or a prompt signal is displayed additionally, and the circuit is in a disturbed state.
In the above compensation circuit, the voltage at the output terminal of the amplifier is equal to the difference between the positive input terminal and the negative input terminal of the amplifier multiplied by a gain (K) represented by V OUT+ ＝K*(V IN+ -V IN- ) (ii) a The amplifier may further comprise an amplifier output negative terminal, wherein the difference between the amplifier output terminal and the amplifier output negative terminal is equal to the difference between the amplifier input positive terminal and the amplifier input negative terminal multiplied by a gain (K) expressed by V OUT+ -V OUT- ＝K*(V IN+ -V IN- )。
In the above-mentioned multiple sensor compensation circuit, the sensor is a bridge sensor, which includes four resistors, the first resistor is connected between the first input terminal and the first output terminal, the second resistor is connected between the second input terminal and the first output terminal, the third resistor is connected between the first input terminal and the second output terminal, and the fourth resistor is connected between the second input terminal and the second output terminal.
Extracting and compiling the section of characters according to partial characteristics of the invention; other features will be described in subsequent paragraphs. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims.
Drawings
Fig. 1 is a schematic structural diagram of a sensor compensation circuit according to a first embodiment of the present invention.
Fig. 2A and 2B provide a method of operating the sensor compensation circuit of fig. 1.
Fig. 3 is a schematic diagram of a sensor compensation circuit including an adc, an arithmetic circuit and a display provided in fig. 1.
Fig. 4 is a schematic structural diagram of another sensor compensation circuit according to a second embodiment of the present invention.
Fig. 5A and 5B illustrate a method of operating the sensor compensation circuit of fig. 4.
Fig. 6 is a schematic diagram of a sensor compensation circuit including an adc, an arithmetic circuit and a display, which is provided based on fig. 4.
Fig. 7 shows another structure of the amplifier according to the present invention.
Description of the reference numerals
10. First resistance of sensor 101
102. Second resistor 103 and third resistor
104. Fourth resistor 105 first input terminal
106. Second input terminal 107 first output terminal
108. Second output terminal 21 first power supply terminal
22. Second power supply terminal 301 first switch
302. Second switch 303 third switch
304. Fourth switch 40 amplifier
401. Amplifier input plus terminal 402 amplifier input minus terminal
403. Amplifier output 404 amplifier offset
405. Amplifier output negative terminal 50 analog-to-digital converter
501. Digital data 60 arithmetic circuit
601. Noise threshold 602 output data
603. Prompt signal 70 display
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a sensor compensation circuit according to a first embodiment of the present invention is shown. The sensor compensation circuit includes a sensor 10, four switches, and an amplifier 40. Wherein the first switch 301 is connected between the first power supply terminal 21 and the first input terminal 105. The second switch 302 is connected between the first power supply terminal 21 and the second input terminal 106. The third switch 303 is connected between the second power supply terminal 22 and the first input terminal 105. The fourth switch 304 is connected between the second power supply terminal 22 and the second input terminal 106. The first output terminal 107 and the second output terminal 108 are respectively connected to the amplifier input positive terminal 401 and the amplifier input negative terminal 402, and the voltage of the amplifier output terminal 403 is multiplied by a gain according to the voltage difference between the amplifier input positive terminal 401 and the amplifier input negative terminal 402.
In the sensor compensation circuit, the sensor 10 is a bridge sensor and includes four resistors. The first resistor 101 is connected between the first input terminal 105 and the first output terminal 107. The second resistor 102 is connected between the second input terminal 106 and the first output terminal 107. The third resistor 103 is connected between the first input terminal 105 and the second output terminal 108. The fourth resistor 104 is connected between the second input terminal 106 and the second output terminal 108.
The sensor compensation circuit is divided into two operation modes; a first mode of operation and a second mode of operation. The equivalent circuit diagram of the first operation mode is shown in fig. 2A, wherein the first switch 301 and the fourth switch 304 are turned on, the second switch 302 and the third switch 303 are turned off, and the first power supply terminal 21 is connected to the first input terminal 105, and the second power supply terminal 22 is connected to the second input terminal 106. The equivalent circuit diagram of the second operation mode is shown in fig. 2B, wherein the second switch 302 and the third switch 303 are turned on, the first switch 301 and the fourth switch 304 are turned off, the first power supply terminal 21 is connected to the second input terminal 106, and the second power supply terminal 22 is connected to the first input terminal 105.
Assuming that the voltage difference between the first power supply terminal 21 and the second power supply terminal 22 is Vin, the resistances of the first resistor 101, the second resistor 102 and the third resistor 103 in the sensor 10 are all R1, the resistance of the fourth resistor 104 is R2, the voltage value of the amplifier offset 404 is Vos, and the gain of the amplifier is K, the voltage value of the amplifier output terminal 403 in the first operation mode is as follows:
Vout1＝K*(V+-V-)＝K*(Vos+(Vin/2)-(Vin*R2/(R1+R2)))
as for the voltage value of the amplifier output 403 in the second operation mode, the following is true:
Vout2＝K*(V+-V-)＝K*(Vos+(Vin/2)-(Vin*R1/(R1+R2)))
the subtraction result (Vout 1-Vout 2) of the voltage values of the amplifier output terminal 403 at the first operation timing and the second operation timing is
Vout1-Vout2＝K*(Vin*(R1-R2)/(R1+R2))
＝2*K*((Vin/2)-(Vin*R2/(R1+R2)))
The subtraction results in the elimination of the voltage Vos of the amplifier offset 404 and the leakage current caused by the trace between the sensor 10 and the amplifier 40 can be compensated.
The addition result (Vout 1+ Vout 2) of the voltage values of the amplifier output terminal 403 at the first operation timing and the second operation timing is:
Vout1+Vout2＝K*(2*Vos+Vin-Vin)＝2*K*Vos
the addition result cancels the input voltage Vin and depends only on the voltage value (Vos) of the amplifier offset 403 and the amplifier gain (K).
Fig. 3 is further supplemented with an adc 50, an operational circuit 60 and a display 70 according to the first embodiment of the invention. The adc 50 converts the voltage at the output 403 of the amplifier into a digital data 501, and then connects to an operation circuit 60 to operate on the digital data 501 generated in the first and second operation modes. The output data 602 is obtained by subtracting the digital data 501 generated in the first operation mode and the second operation mode and dividing the subtracted result by 2, or the output data 602 is generated according to the digital data 501 generated in the first operation mode.
The sensor compensation circuit causes a noise voltage Vn to be present at the voltage at the output of the sensor if an abnormal disturbance occurs in the first operation mode, such that the voltage at the output 403 of the amplifier has a value of
Vout1＝K*(V+-V-)＝K*(Vn+Vos+(Vin/2)-(Vin*R2/(R1+R2)))
If there is no abnormal interference in the second operation mode, the voltage value at the output terminal 403 of the amplifier is set to be
Vout2＝K*(V+-V-)＝K*(Vos+(Vin/2)-(Vin*R1/(R1+R2)))
The result of adding the voltage values of the amplifier output terminal 403 at the first operation timing and the second operation timing (Vout 1+ Vout 2) is thus
Vout1+Vout2＝K*(Vn+2*Vos+Vin-Vin)＝2*K*Vos+(K*Vn)
The addition result (Vout 1+ Vout 2) is one more term K × Vn than the normal result 2 × K × vos. The subtraction result (Vout 1-Vout 2) of the voltage values of the amplifier output 403 at the first operation timing and the second operation timing cannot offset the noise voltage Vn, and thus the output data 602 is also affected.
Therefore, a noise threshold 601 (Vth) is designed, and when the addition result (Vout 1+ Vout 2) is greater than the noise threshold 601 (Vth), the circuit is considered to be abnormally disturbed, the output data 602 is not updated, and the value is maintained at a value which is not considered to be disturbed.
In the sensor compensation circuit, the noise threshold 601 (Vth) is a fixed default value or a value estimated based on the addition result (Vout 1+ Vout 2). For example, if the normal addition result is 2 × k × vos, an average value may be calculated according to the addition results (Vout 1+ Vout 2) in a period of time, and the noise threshold 601 (Vth) is determined according to the average value. Or finding out a maximum value according to the addition result (Vout 1+ Vout 2) within a period of time, and determining the noise threshold 601 (Vth) according to the maximum value.
The sensor compensation circuit further includes a prompt signal 603, and when the addition result (Vout 1+ Vout 2) of the voltages at the output terminal 403 of the amplifier generated in the first operation mode and the second operation mode is greater than the noise threshold 601 (Vth), the prompt signal 603 indicates that the circuit is in a disturbed state.
The sensor compensation circuit further includes a display 70 for displaying the value of the output data 602. When the sum of the voltages at the output 403 of the amplifier generated in the first and second operation modes is greater than the noise threshold 601, the circuit is considered to be disturbed, and the output data 602 displayed on the display 70 is caused to flash or a prompt signal 603 is additionally displayed to indicate that the circuit is in a disturbed state.
Referring to fig. 4, a sensor compensation circuit according to a second embodiment of the present invention is shown. The sensor compensation circuit includes a sensor 10, four switches, and an amplifier 40. Wherein the first power supply terminal 21 is connected to the first input terminal 105, and the second power supply terminal 22 is connected to the second input terminal 106. The first switch 301 is connected between the first output terminal 107 and the positive amplifier input terminal 401. The second switch 302 is connected between the first output terminal 107 and the negative amplifier input terminal 402. The third switch 303 is connected between the second output terminal 108 and the positive amplifier input terminal 401. The fourth switch 304 is connected between the second output terminal 108 and the negative amplifier input terminal 402. And the voltage at the output terminal 403 of the amplifier is multiplied by a gain according to the voltage difference between the positive amplifier input terminal 401 and the negative amplifier input terminal 402.
In the sensor compensation circuit, the sensor 10 is a bridge sensor and includes four resistors. The first resistor 101 is connected between the first input terminal 105 and the first output terminal 107. The second resistor 102 is connected between the second input terminal 106 and the first output terminal 107. The third resistor 103 is connected between the first input terminal 105 and the second output terminal 108. The fourth resistor 104 is connected between the second input terminal 106 and the second output terminal 108.
The sensor compensation circuit described above is divided into two modes of operation: a first mode of operation and a second mode of operation. The equivalent circuit diagram of the first operation mode is shown in fig. 5A, wherein the first switch 301 and the fourth switch 304 are turned on, the second switch 302 and the third switch 303 are turned off, and the first output terminal 107 is connected to the positive amplifier input terminal 401, and the second output terminal 108 is connected to the negative amplifier input terminal 402. The equivalent circuit diagram of the second operation mode is shown in fig. 5B, wherein the second switch 302 and the third switch 303 are turned on, the first switch 301 and the fourth switch 304 are turned off, and the first output terminal 107 is connected to the negative amplifier input terminal 402, and the second output terminal 108 is connected to the positive amplifier input terminal 401.
Assuming that the voltage difference between the first power supply terminal 21 and the second power supply terminal 22 is Vin, the resistances of the first resistor 101, the second resistor 102 and the third resistor 103 in the sensor 10 are R1, the resistance of the fourth resistor 104 is R2, the voltage value of the offset 404 of the amplifier is Vos, the gain of the amplifier is K, and the voltage value Vout1 of the output 403 of the amplifier is as follows:
Vout1＝K*(V+-V-)＝K*(Vos+(Vin/2)-(Vin*R2/(R1+R2)))
as for the voltage value of the amplifier output 403 in the second operation mode, the following is true:
Vout2＝K*(V+-V-)＝K*(Vos-(Vin/2)+(Vin*R2/(R1+R2)))
the subtraction result (Vout 1-Vout 2) of the voltage values of the amplifier output terminal 403 at the first operation timing and the second operation timing is
Vout1-Vout2＝K*(Vin*(R1-R2)/(R1+R2))
＝2*K*((Vin/2)-(Vin*R2/(R1+R2)))
The subtraction result (Vout 1-Vout 2) cancels the voltage value Vos of the amplifier offset 404.
The addition result (Vout 1+ Vout 2) of the voltage values of the amplifier output terminal 403 at the first operation timing and the second operation timing is:
Vout1+Vout2＝K*(2*Vos)＝2*K*Vos
the addition result (Vout 1+ Vout 2) cancels the input voltage Vin, depending only on the voltage value (Vos) of the amplifier offset 403 and the amplifier gain (K).
FIG. 6 is a diagram of a second embodiment of the present invention, which is supplemented by an analog-to-digital converter 50, an operational circuit 60 and a display 70. The adc 50 converts the voltage at the output terminal 403 of the amplifier into a digital data 501, and then connects to the operation circuit 60, and performs an operation on the digital data 501 generated in the first operation mode and the second operation mode, wherein the digital data 501 generated in the first operation mode and the second operation mode is subtracted and then divided by 2 to obtain an output data 602, or the output data 602 is generated according to the digital data 501 generated in the first operation mode.
The sensor compensation circuit assumes that the abnormal disturbance occurs in the first operation mode, and causes a noise voltage Vn to exist in the voltage at the output terminal of the sensor, so that the voltage at the output terminal 403 of the amplifier has a value of
Vout1＝K*(V+-V-)＝K*(Vn+Vos+(Vin/2)-(Vin*R2/(R1+R2)))
As for the voltage value of the amplifier output 403 in the second operation mode, the following is true:
Vout2＝K*(V+-V-)＝K*(Vos-(Vin/2)+(Vin*R2/(R1+R2)))
the result of adding the voltage values (Vout 1 and Vout 2) of the amplifier output terminal 403 at the first operation timing and the second operation timing is
Vout1+Vout2＝K*(Vn+2*Vos)＝2*K*Vos+(K*Vn)
The addition result (Vout 1+ Vout 2) is one more term K × Vn than the normal result 2 × K × vos. The subtraction result (Vout 1-Vout 2) of the voltage values of the amplifier output terminal 403 in the first operation timing and the second operation timing does not cancel the noise voltage Vn, and thus the output data 602 is also affected.
Therefore, a noise threshold 601 (Vth) is designed, and when the addition result (Vout 1+ Vout 2) is greater than the noise threshold 601 (Vth), the circuit is considered to be abnormally interfered, the output data 602 is not updated, and the value which has not been considered to be interfered before is maintained.
In the sensor compensation circuit, the noise threshold 601 (Vth) is a fixed default value or a value estimated based on the addition result (Vout 1+ Vout 2). For example, the normal addition result is 2 × k × vos, an average value can be calculated according to the addition result (Vout 1+ Vout 2) within a period of time, and the noise threshold 601 (Vth) is determined according to the average value. Or find a maximum value according to the addition result (Vout 1+ Vout 2) within a period of time, and then determine the noise threshold 601 (Vth) according to the maximum value.
The sensor compensation circuit further includes a prompt signal 603, and when the addition result (Vout 1+ Vout 2) of the voltages at the output terminal 403 of the amplifier generated in the first operation mode and the second operation mode is greater than the noise threshold 601 (Vth), the prompt signal 603 indicates that the circuit is in a disturbed state.
The sensor compensation circuit also includes a display 70 for displaying the output data 602. When the sum of the voltages at the output 403 of the amplifier (Vout 1+ Vout 2) generated in the first and second operation modes is greater than the noise threshold 601, the circuit is considered to be disturbed, and the output data displayed on the display 70 is flashed, or a prompt signal 603 indicating that the circuit is in a disturbed state is displayed
According to the invention, the voltage at the output 403 of the amplifier is equal to the difference between the positive input 401 and the negative input 402 of the amplifier multiplied by a gain (K), which is expressed by V OUT+ ＝K*(V IN+ -V IN- ). In addition, referring to fig. 7, the amplifier 40 may further include an amplifier output negative terminal 405, and the voltage difference between the amplifier output terminal 403 and the amplifier output negative terminal 405 is equal to the voltage difference between the amplifier input positive terminal 401 and the amplifier input negative terminal 402, and then multiplied by a gain (K) represented by V OUT+ -V OUT- ＝K*(V IN+ -V IN- )。
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent application shall be subject to the appended claims.
Claims (13)
1. A sensor compensation circuit, comprising:
a sensor including a first input, a second input, a first output, and a second output;
a first switch connected between the first power supply terminal and the first input terminal;
the second switch is connected between the first power supply end and the second input end;
a third switch connected between the second power supply terminal and the first input terminal;
a fourth switch connected between the second power supply terminal and the second input terminal; and
an amplifier, the positive amplifier input terminal and the negative amplifier input terminal are connected to the first output terminal and the second output terminal respectively, and the voltage of the amplifier output terminal is multiplied by a gain according to the voltage difference between the positive amplifier input terminal and the negative amplifier input terminal,
wherein the control method of the first switch, the second switch, the third switch, and the fourth switch includes:
a first operation mode for turning on the first switch and the fourth switch, turning off the second switch and the third switch, connecting the first power supply terminal to the first input terminal, and connecting the second power supply terminal to the second input terminal;
a second operation mode, turning on the second switch and the third switch, turning off the first switch and the fourth switch, connecting the first power supply terminal to the second input terminal, and connecting the second power supply terminal to the first input terminal; the offset is compensated by subtracting the voltages at the output of the amplifier resulting from the first and second modes of operation.
2. A sensor compensation circuit, comprising:
a sensor including a first input, a second input, a first output, and a second output;
a first switch connected between the first power supply terminal and the first input terminal;
the second switch is connected between the first power supply end and the second input end;
a third switch connected between the second power supply terminal and the first input terminal;
a fourth switch connected between the second power supply terminal and the second input terminal; and
an amplifier, the positive amplifier input terminal and the negative amplifier input terminal are connected to the first output terminal and the second output terminal respectively, and the voltage of the amplifier output terminal is multiplied by a gain according to the voltage difference between the positive amplifier input terminal and the negative amplifier input terminal,
wherein the control method of the first switch, the second switch, the third switch, and the fourth switch comprises:
a first operation mode for turning on the first switch and the fourth switch, turning off the second switch and the third switch, connecting the first power supply terminal to the first input terminal, and connecting the second power supply terminal to the second input terminal;
a second operation mode for turning on the second switch and the third switch, turning off the first switch and the fourth switch, connecting the first power supply terminal to the second input terminal, and connecting the second power supply terminal to the first input terminal; and calculating the magnitude of the offset based on the result of the addition of the voltages at the output of the amplifier resulting from the first and second modes of operation.
3. The sensor compensation circuit of any of claims 1-2, comprising an analog-to-digital converter for converting the voltage at the output of the amplifier to a digital data; and an operational circuit, which is operated according to the digital data, and subtracts the voltage of the output end of the amplifier generated according to the first operation mode and the second operation mode and divides the subtracted voltage by 2, or generates output data according to the voltage of the output end of the amplifier generated according to the first operation mode.
4. The sensor compensation circuit of claim 2, comprising:
an analog-to-digital converter for converting the voltage at the output of the amplifier into a digital data;
an operational circuit, which performs operation according to the digital data, and subtracts the voltage of the output end of the amplifier generated according to the first operation mode and the second operation mode and divides the subtracted voltage by 2, or generates output data according to the voltage of the output end of the amplifier generated according to the first operation mode; and
and a noise threshold, wherein the output data is fixed when the sum of the voltages at the output terminals of the amplifier generated in the first and second operation modes is greater than the noise threshold.
5. A sensor compensation circuit, comprising:
a sensor, wherein a first input terminal is connected to a first power supply terminal, a second input terminal is connected to a second power supply terminal, and the sensor comprises a first output terminal and a second output terminal;
an amplifier comprising an amplifier input positive terminal, an amplifier input negative terminal, and an amplifier output terminal, wherein the voltage at the amplifier output terminal is multiplied by a gain according to the voltage difference between the amplifier input positive terminal and the amplifier input negative terminal;
a first switch connected between the first output terminal and the positive amplifier input terminal;
a second switch connected between said first output terminal and said amplifier input negative terminal;
a third switch connected between the second output terminal and the positive input terminal of the amplifier; and
a fourth switch connected between the second output terminal and the negative terminal of the amplifier input,
wherein the control method of the first switch, the second switch, the third switch, and the fourth switch includes:
a first operating mode in which the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, the first output terminal is connected to the positive amplifier input terminal, and the second output terminal is connected to the negative amplifier input terminal;
a second operation mode, wherein the second switch and the third switch are turned on, the first switch and the fourth switch are turned off, the first output terminal is connected to the negative amplifier input terminal, and the second output terminal is connected to the positive amplifier input terminal; the offset is compensated by subtracting the voltages at the output of the amplifier resulting from the first and second modes of operation.
6. A sensor compensation circuit, comprising:
a sensor, wherein a first input terminal is connected to a first power supply terminal, a second input terminal is connected to a second power supply terminal, and the sensor comprises a first output terminal and a second output terminal;
an amplifier comprising an amplifier input positive terminal, an amplifier input negative terminal, and an amplifier output terminal, wherein the voltage at the amplifier output terminal is multiplied by a gain according to the voltage difference between the amplifier input positive terminal and the amplifier input negative terminal;
a first switch connected between the first output terminal and the positive input terminal of the amplifier;
a second switch connected between said first output terminal and said negative amplifier input terminal;
a third switch connected between the second output terminal and the positive input terminal of the amplifier; and
a fourth switch connected between the second output terminal and the negative terminal of the amplifier input,
wherein the control method of the first switch, the second switch, the third switch, and the fourth switch includes:
a first operating mode in which the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, the first output terminal is connected to the positive amplifier input terminal, and the second output terminal is connected to the negative amplifier input terminal;
a second operation mode, wherein the second switch and the third switch are turned on, the first switch and the fourth switch are turned off, the first output terminal is connected to the negative amplifier input terminal, and the second output terminal is connected to the positive amplifier input terminal; and calculating the magnitude of the offset based on the result of the addition of the voltages at the output of the amplifier resulting from the first and second modes of operation.
7. The sensor compensation circuit of any of claims 5-6 including an analog-to-digital converter for converting the voltage at the output of the amplifier to a digital data; and an operational circuit, which is operated according to the digital data, and subtracts the voltage of the output end of the amplifier generated according to the first operation mode and the second operation mode and divides the subtracted voltage by 2, or generates output data according to the voltage of the output end of the amplifier generated according to the first operation mode.
8. The sensor compensation circuit of claim 6, comprising:
an analog-to-digital converter for converting the voltage at the output of the amplifier into a digital data;
an operational circuit, which performs operation according to the digital data, and subtracts the voltage of the output end of the amplifier generated according to the first operation mode and the second operation mode and divides the subtracted voltage by 2, or generates output data according to the voltage of the output end of the amplifier generated according to the first operation mode; and
and a noise threshold, wherein the output data is fixed when the sum of the voltages at the output end of the amplifier generated in the first operation mode and the second operation mode is greater than the noise threshold.
9. The sensor compensation circuit of claim 4 or 8, wherein the noise threshold is a fixed default value or a value derived based on the summation of the voltages at the output terminals of the amplifier generated in the first and second modes of operation.
10. The sensor compensation circuit of claim 4 or 8, including a cue signal, wherein the cue signal is used to indicate that the circuit is in a disturbed state when the sum of the voltages at the output of the amplifier resulting from the first and second modes of operation is greater than the noise threshold.
11. The sensor compensation circuit of claim 4 or 8, including a display for displaying output data, wherein when the sum of the voltages at the output of the amplifier produced in the first and second modes of operation is greater than the noise threshold, the output data is caused to flash or otherwise display a signal indicating that the circuit is in a disturbed state.
12. The sensor compensation circuit of any one of claims 1-2, 4-6, or 8 wherein the amplifier further comprises an amplifier output negative terminal, the difference between the amplifier output terminal and the amplifier output negative terminal being equal to the difference between the amplifier input positive terminal and the amplifier input negative terminal multiplied by a gain.
13. The sensor compensation circuit of any one of claims 1-2, 4-6 or 8 wherein the sensor is a bridge sensor comprising a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the first resistor is connected between the first input terminal and the first output terminal, the second resistor is connected between the second input terminal and the first output terminal, the third resistor is connected between the first input terminal and the second output terminal, and the fourth resistor is connected between the second input terminal and the second output terminal.
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| EP3396397B1 (en) * | 2017-04-28 | 2019-11-20 | Melexis Technologies SA | Bridge sensor biasing and readout |
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