Data read-out circuit of gas sensitive sensor and detection device

Abstract

The invention provides a data read-out circuit of a gas sensitive sensor. The data read-out circuit comprises a current input module, a gas sensitive resistor, multiple voltage controlled resistors, an operational amplifier and a successive approximation logic unit; the current input module provides two paths of same currents; one end of the gas sensitive resistor is connected with the output end of the first loop, and the other end of the gas sensitive resistor is grounded; one end of the serial-connected voltage controlled resistors is connected with the output end of a second loop, and the other end of the serial-connected voltage controlled resistors is grounded via a neutralizing resistor; two input ends of the operational amplifier are connected with output voltages of the first loop and the second loop respectively, the two received output voltages are compared, and a comparison voltage is output; and the successive approximation logic unit compares the comparison voltage with a preset determination voltage, successive approximation calibration is carried out on a digital signal sequence which controls voltage controlled resistors according to a comparison result, and the calibrated digital signal sequence serves as a digital signal output by the data read-out circuit. The operational amplifier only plays a negative feedback role, nonlinear characteristics of the operational amplifier has no influence on the system, the voltage controlled resistors are controlled in the digital manner, and nonlinear factors caused by analog control are eliminated.

Description

technical field [0001] The invention relates to integrated circuit technology, in particular to a data readout circuit and detection device of a gas sensor. Background technique [0002] At present, the main sensor parameters are realized by amplifying the output signal of the sensor, and then outputting it through the analog-to-digital converter. Due to the extremely limited linear working area of ​​the operational amplifier, the nonlinear area has a great influence on the data output of the gas sensor. Because the resistance of the gas sensor changes linearly with the gas solubility, the traditional way is to pass the signal through the amplifier, and then obtain the output signal through the analog-to-digital converter, but in this process, the nonlinear characteristics of the amplifier It affects the linear characteristics of the final output signal, and it is usually necessary to add a linear calibration circuit behind the amplifier, but the nonlinear characteristics o...

AI Technical Summary

Problems solved by technology

Due to the extremely limited linear working area of ​​the operational amplifier, the nonlinear area has a great influence on the data output of the gas sensor

Because the resistance of the gas sensor changes linearly with the gas solubility, the traditional way is to pass the signal through the amplifier, and then obtain the output signal through the analog-to-digital converter, but in this process, the nonlinear characteristics of the amplifier It affects the linear characteristics of the final output signal. Usually, it is necessary to add a linear calibration circuit behind the amplifier, but the nonlinear characteristics of the operational amplifier cannot be accurately calculated. Even if the linear calibration circuit is added, the influence of the nonlinear characteristics of the amplifier cannot be completely eliminated.

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