Resistance high-precision measuring system and method with combination of differential method and proportion method

Abstract

The invention discloses a resistance high-precision measuring system and method with combination of a differential method and a proportion method. The system comprises a constant current source, a reference resistor, a first differential amplifier, a programmable gain amplifier, an analog-to-digital converter, a microprocessor, a digital-analog converter and a measured resistor interface, the measured resistor interface is connected to a measured resistor, the reference resistor and the measured resistor are connected in series to form a serial connection branch circuit connected between the constant current source and the ground, two input terminals of the first differential amplifier are respectively connected with two terminals of the reference resistor, an output terminal of the firstdifferential amplifier is connected with a voltage reference terminal of the analog-to-digital converter, a first input terminal of the programmable gain amplifier is used for being connected to a to-ground single-end voltage of the measured resistor, a second input terminal of the programmable gain amplifier is connected with an analog output terminal of the digital-to-analog converter or the ground in a controlled manner, an output terminal of the programmable gain amplifier is connected with an analog input terminal of the analog-to-digital converter, and digital output terminals of the analog-to-digital converter and the digital-to-analog converter are both connected with the microprocessor. According to the system, the influence of power supply fluctuation can be overcome, the cost islow, and the measuring precision is high.

Description

technical field [0001] The invention relates to the field of sensors and detection technology and instruments, and specifically belongs to a low-cost and high-precision resistance measurement system and method combining a differential method and a proportional method. Background technique [0002] Accurate measurement of resistance is the basis for resistive sensors to achieve high-precision measurement. Resistive sensors are widely used in practical engineering, and it is also common in occasions where high-precision measurement of the sensed resistance is required. [0003] In the automatic detection system, the high-precision measurement of the resistance mostly adopts the digital measurement method, and the measurement device generally includes a microprocessor (CPU), an analog-to-digital converter (ADC), and a signal input circuit. The accuracy of the digital measurement system mainly depends on the accuracy or the number of bits of the ADC. Generally, the more the num...

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Problems solved by technology

However, this method is limited in practice, because it is not easy to obtain the same standard quantity with a small difference from the measured value, and sometimes it cannot be obtained.

[0007] Therefore, it is difficult to achieve high-precision resistance measurement while reducing the cost of the measurement system by using the ratio method or the differential method alone.

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