Reading circuit used for sensor

Abstract

The invention relates to a reading circuit used for a sensor. The reading circuit comprises two levels of operational amplifiers, a chopper, a buffer and a 2-order 3-bit quantized Sigma-Delta analog / digital converter; the two levels of operational amplifiers amplify a weak voltage signal outputted from the sensor by a resistance ratio under a closed loop work state; the input / output chopper is used for reducing the direct current detuning voltage and low-frequency 1 / f noise of the operational amplifiers; the buffer performs isolation protection on the output signal of the operational amplifiers and provides a certain voltage driving capacity at the same time; and the 2-order 3-bit quantized Sigma-Delta analog / digital converter converts the amplified sensor voltage signal into a digital code and outputs to a DSP (digital signal processor) for processing.

Description

Technical field [0001] The invention relates to the field of CMOS analog integrated circuit design, in particular to a sensor readout circuit. Background technique [0002] In nature, any object whose temperature is higher than absolute zero will produce infrared radiation. Measuring its intensity and converting it into other forms of energy for application is the main task of infrared detectors. As one of the most important infrared detectors, thermopile has been widely used in infrared imaging, infrared early warning, infrared detection and other fields. With the rapid development of microelectronics technology, the solution of semiconductor materials as the matrix of thermopile is becoming more and more mature, and the silicon-based thermopile manufactured by micromechanical technology has been successfully developed. [0003] The thermopile infrared sensor can be integrated with a standard silicon-based process to further reduce the production cost of the chip and improve the ...

AI Technical Summary

Problems solved by technology

However, this solution has the following three shortcomings: (1) Due to the system architecture of an open-loop operational amplifier, the overall system gain is susceptible to changes in process, temperature and other conditions, resulting in nonlinear changes in gain and temperature, and limited temperature detection accuracy ; (2) A band-pass filter is introduced in the system to eliminate the residual offset voltage, which increases the circuit complexity and reduces the reliability of the system while improving a certain detection accuracy; (3) There is no integrated analog-to-digital conversion in this scheme When the system is implemented, an analog-to-digital converter circuit needs to be added to the system circuit board for quantization. The scale is large, which increases the difficulty of system application.

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