A bridge sensor signal conditioning circuit and method

Abstract

The application relates to a bridge sensor signal conditioning circuit and method. The circuit of the application comprises a bridge sensor signal conditioning chip U1, a common-mode input resistor R1 and a platinum resistance sensor RTD, the current excitation end BDR and the positive input end INP of the bridge sensor signal conditioning chip U1 are connected, the platinum resistance sensor RTD is connected between the positive input end INP and the negative input end INM of the bridge sensor signal conditioning chip U1, and the common-mode input resistor R1 is connected between the negative input end INM of the bridge sensor signal conditioning chip U1 and the ground end VSS. The application realizes the conditioning of the platinum resistance signal by the single-chip bridge sensor signal conditioning circuit through a peripheral circuit and a calibration algorithm, and the calibration precision is high.

Description

Technical Field

[0001] This invention relates to the field of signal communication in aviation, marine and industrial control, and to a bridge sensor signal conditioning circuit and method, specifically to a novel conditioning method for platinum resistance signals based on a single-chip bridge sensor signal conditioning circuit. Background Technology

[0002] Platinum resistance thermometers (PTTs) offer high accuracy and a wide measurement range, making them widely applicable. However, due to their material properties, input drift and nonlinearity during resistive sensor signal transmission cause significant errors in the sensor's characteristics, necessitating signal conditioning. Existing single-chip signal conditioning circuits are mostly used in bridge sensors, lacking corresponding conditioning circuits and methods for PTTs. Traditional PTT conditioning circuits are often board-level circuits, resulting in complex hardware systems that affect overall accuracy and occupy a large size, contradicting the trend towards smaller, lighter, and more compact temperature sensors. Summary of the Invention

[0003] To address the technical problems existing in the background art, the present invention provides a bridge sensor signal conditioning circuit and method, which realizes the conditioning of platinum resistance signals by a single-chip bridge sensor signal conditioning circuit through peripheral circuits and calibration algorithms.

[0004] The technical solution of the present invention is: a bridge sensor signal conditioning circuit, characterized in that: the conditioning circuit includes a bridge sensor signal conditioning chip U1, a common-mode input resistor R1, and a platinum resistance sensor RTD; the current excitation terminal BDR of the bridge sensor signal conditioning chip U1 is connected to the positive input terminal INP; the platinum resistance sensor RTD is connected between the positive input terminal INP and the negative input terminal INM of the bridge sensor signal conditioning chip U1; and the common-mode input resistor R1 is connected between the negative input terminal INM of the bridge sensor signal conditioning chip U1 and the ground terminal VSS.

[0005] Furthermore, the conditioning circuit also includes a voltage regulator capacitor C1, which is connected between the power supply terminal VDD and the ground terminal VSS of the bridge sensor signal conditioning chip U1.

[0006] Furthermore, the conditioning circuit also includes an output filter capacitor C2, which is connected between the output terminal OUT of the bridge sensor signal conditioning chip U1 and the ground terminal VSS.

[0007] Furthermore, the bridge sensor signal conditioning chip U1 includes a current source excitation, a gain amplifier, a storage unit, a digital-to-analog converter (DAC), and an embedded temperature sensor; the embedded temperature sensor is connected to the storage unit, the storage unit is connected to the DAC, and the DAC is connected to the current source excitation and the gain amplifier, respectively.

[0008] Furthermore, the digital-to-analog converter (DAC) includes an output zero-point adjustment ODAC, a span adjustment FSODAC, an output zero-point temperature coefficient OTCDAC, and a span temperature coefficient FSOTCDAC. The storage unit is connected to the output zero-point adjustment ODAC, the span adjustment FSODAC, the output zero-point temperature coefficient OTCDAC, and the span temperature coefficient FSOTCDAC, respectively. The span adjustment FSODAC and the span temperature coefficient FSOTCDAC are connected to the current source excitation, respectively. The output zero-point adjustment ODAC and the output zero-point temperature coefficient OTCDAC are connected to the gain amplifier.

[0009] A method for implementing the above-described bridge sensor signal conditioning circuit, characterized in that the method includes the following steps:

[0010] 1) Configure the span adjustment FSODAC and span temperature coefficient FSOTCDAC so that the current source excitation supplies power to the platinum resistance, and the potential across the platinum resistance is close to half of the supply voltage;

[0011] 2) Calculate the resistance variation range and input voltage range of the platinum resistance thermometer based on the actual measured temperature range;

[0012] 3) Calculate and configure the gain factor of the gain amplifier. The calculation method is: Gain = Ideal output voltage range / Input voltage range;

[0013] 4) Measure the output voltage at the OUT terminal at room temperature, and adjust the output zero-point temperature coefficient OTCDAC so that the output voltage at the OUT terminal basically meets the following conditions:

[0014] (Output voltage at OUT terminal - preset zero point) / preset span = (room temperature - minimum temperature) / (maximum temperature - minimum temperature) and record the value of the output zero point temperature coefficient OTCDAC at this time. This output zero point temperature coefficient OTCDAC remains unchanged during subsequent calibration.

[0015] 5) Set the temperature to the lowest point, measure the output voltage at the OUT terminal, adjust the output zero point and adjust the ODAC value so that the output voltage at the OUT terminal is equal to the preset zero point, and record the corresponding ODAC value.

[0016] 6) Set the temperature of the incubator to the highest temperature point, measure the output voltage at the OUT terminal, adjust the output zero point adjustment 0DAC value so that the output voltage at the OUT terminal is equal to (preset zero point + span voltage), and record the corresponding zero point adjustment 0DAC value.

[0017] 7) Adjust the temperature of the chamber to room temperature, adjust the 0DAC data to generate compensation data based on the output zero point recorded at the three temperature points, and write it into the storage unit. Then, conduct tests and verifications at full temperature.

[0018] Platinum resistance thermometers (PTS) inherently exhibit output errors and nonlinearities due to their material properties. This invention utilizes a bridge-type sensor signal conditioning chip to amplify the signal while simultaneously addressing its nonlinearity. A constant current supply is provided to the PTS, amplifying and compensating the small input signal into a high-precision, controllable voltage output. The embedded temperature sensor within the bridge-type sensor signal conditioning chip compensates for the output at every temperature point across the entire temperature range, resulting in a linear output. Therefore, this invention offers the following advantages: signal amplification via the bridge-type sensor signal conditioning chip, and high calibration accuracy through the embedded temperature sensor and storage unit for nonlinearity correction of the PTS. Attached Figure Description

[0019] Figure 1 This is a circuit diagram of the present invention;

[0020] Figure 2 This is a circuit diagram of the bridge sensor signal conditioning chip of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] See Figure 1 The structure of the bridge sensor signal conditioning circuit of the present invention includes a bridge sensor signal conditioning chip U1, a common-mode input resistor R1, a platinum resistance sensor RTD, a voltage regulator capacitor C1, and a filter capacitor C2. The current excitation terminal BDR of the bridge sensor signal conditioning chip U1 is connected to the positive input terminal INP. The platinum resistance sensor RTD is connected between the positive input terminal INP and the negative input terminal INM of the bridge sensor signal conditioning chip U1. The common-mode input resistor R1 is connected between the negative input terminal INM of the bridge sensor signal conditioning chip U1 and the ground terminal VSS. The voltage regulator capacitor C1 is connected between the power supply terminal VDD and the ground terminal VSS of the bridge sensor signal conditioning chip U1. The output filter capacitor C2 is connected between the output terminal OUT of the bridge sensor signal conditioning chip U1 and the ground terminal VSS.

[0023] See Figure 2The structure of the bridge sensor signal conditioning chip U1 of the present invention includes a current source excitation, a gain amplifier, a storage unit, a digital-to-analog converter (DAC), and an embedded temperature sensor. The embedded temperature sensor is connected to the storage unit, the storage unit is connected to the DAC, and the DAC is connected to both the current source excitation and the gain amplifier. In this embodiment, the DAC includes an output zero-point adjustment ODAC, a span adjustment FSODAC, an output zero-point temperature coefficient OTCDAC, and a span temperature coefficient FSOTCDAC. The storage unit is connected to the output zero-point adjustment ODAC, the span adjustment FSODAC, the output zero-point temperature coefficient OTCDAC, and the span temperature coefficient FSOTCDAC. The span adjustment FSODAC and the span temperature coefficient FSOTCDAC are connected to the current source excitation, and the output zero-point adjustment ODAC and the output zero-point temperature coefficient OTCDAC are connected to the gain amplifier.

[0024] In this embodiment, the bridge sensor signal conditioning chip U1 has two power supply terminals: VDD and VDDS, both of which are connected to an external 5V power supply. The power supply terminal VDDS is responsible for powering the storage unit, and the power supply terminal VDD is responsible for powering other units.

[0025] The conditioning method of the bridge sensor signal conditioning circuit of the present invention specifically includes the following steps:

[0026] 1) Configure the span adjustment FSODAC and span temperature coefficient FSOTCDAC so that the current source excitation supplies power to the platinum resistance, and the potential across the platinum resistance is close to half of the supply voltage;

[0027] 2) Calculate the resistance variation range and input voltage range of the platinum resistance thermometer based on the actual measured temperature range;

[0028] 3) Calculate and configure the gain factor of the gain amplifier. The calculation method is: Gain = Ideal output voltage range / Input voltage range;

[0029] 4) Measure the output voltage at the OUT terminal at room temperature, and adjust the output zero-point temperature coefficient OTCDAC so that the output voltage at the OUT terminal basically meets the following conditions:

[0030] (Output voltage at OUT terminal - preset zero point) / preset span = (room temperature - minimum temperature) / (maximum temperature - minimum temperature) and record the value of the output zero point temperature coefficient OTCDAC at this time. This output zero point temperature coefficient OTCDAC remains unchanged during subsequent calibration.

[0031] 5) Set the temperature to the lowest point, measure the output voltage at the OUT terminal, adjust the output zero point and adjust the ODAC value so that the output voltage at the OUT terminal is equal to the preset zero point, and record the corresponding ODAC value.

[0032] 6) Set the temperature of the incubator to the highest temperature point, measure the output voltage at the OUT terminal, adjust the output zero point adjustment 0DAC value so that the output voltage at the OUT terminal is equal to (preset zero point + span voltage), and record the corresponding zero point adjustment 0DAC value.

[0033] 7) Adjust the temperature of the chamber to room temperature, adjust the 0DAC data to generate compensation data based on the output zero point recorded at the three temperature points, and write it into the storage unit. Then, conduct tests and verifications at full temperature.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of implementing a bridge sensor signal conditioning circuit, characterized by: The conditioning circuit comprises a bridge sensor signal conditioning chip U1, a common mode input resistor R1 and a platinum resistance sensor RTD, the current excitation end BDR and the positive input end INP of the bridge sensor signal conditioning chip U1 are connected, the platinum resistance sensor RTD is connected between the positive input end INP and the negative input end INM of the bridge sensor signal conditioning chip U1, the common mode input resistor R1 is connected between the negative input end INM of the bridge sensor signal conditioning chip U1 and the ground end VSS, the conditioning circuit further comprises a voltage stabilizing capacitor C1, the voltage stabilizing capacitor C1 is connected between the power supply end VDD and the ground end VSS of the bridge sensor signal conditioning chip U1, the conditioning circuit further comprises an output filter capacitor C2, the output filter capacitor C2 is connected between the output end OUT and the ground end VSS of the bridge sensor signal conditioning chip U1, the bridge sensor signal conditioning chip U1 comprises a current source excitation, a gain amplifier, a storage unit, a digital-to-analog converter DAC and an embedded temperature sensor; the embedded temperature sensor is connected with the storage unit, the storage unit is connected with the digital-to-analog converter DAC, the digital-to-analog converter DAC is connected with the current source excitation and the gain amplifier respectively, the digital-to-analog converter DAC comprises an output zero point adjustment 0DAC, a span adjustment FSODAC, an output zero point temperature coefficient OTCDAC and a span temperature coefficient FSOTCDAC, the storage unit is connected with the output zero point adjustment 0DAC, the span adjustment FSODAC, the output zero point temperature coefficient OTCDAC and the span temperature coefficient FSOTCDAC respectively, the span adjustment FSODAC and the span temperature coefficient FSOTCDAC are connected with the current source excitation respectively, the output zero point adjustment 0DAC and the output zero point temperature coefficient OTCDAC are connected with the gain amplifier, and the implementation method comprises the following steps: 1) configure the span adjustment FSODAC and the span temperature coefficient FSOTCDAC to make the current source excitation supply power for the platinum resistance, and the potential difference between the platinum resistance is close to one half of the supply voltage; 2) calculate the resistance value change range of the platinum resistance and the input voltage range according to the actual measured temperature range; 3) calculate and configure the gain multiple of the gain amplifier, and the calculation method is: gain = ideal output voltage range / input voltage range; 4) measure the output voltage of the output end OUT at normal temperature, adjust the output zero point temperature coefficient OTCDAC, so that the output voltage of the output end OUT basically meets the following condition: (output voltage of the output end OUT - preset zero point) / preset span = (room temperature - minimum temperature) / (maximum temperature - minimum temperature), and record the value of the output zero point temperature coefficient OTCDAC at this time, which remains unchanged in the subsequent calibration process; 5) adjust the output zero point adjustment 0DAC value to make the output voltage of the output end OUT equal to the preset zero point, and record the corresponding ODAC value when the temperature is adjusted to the minimum temperature point. ​ 6) Adjust the temperature of the oven to the highest temperature point, measure the output voltage of the output OUT, adjust the output zero point adjustment 0DAC value to make the output voltage of the output OUT equal to the sum of the preset zero point and the span voltage, and record the corresponding zero point adjustment 0DAC value; 7) Adjust the temperature of the oven to room temperature, generate compensation data according to the recorded output zero point adjustment 0DAC data at the three temperature points and write it into the storage unit, and then test and verify at full temperature.

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