| Air quality is an important indicator to measure the quality of urban environment.Gas detection has a wide range of applications in industrial and daily fields.Among them,laser gas sensors based on TDLAS technology have been more and more attention paid by researchers by its advantages of real-time online monitoring and high sensitivity.Based on the study of the principle of TDLAS laser sensor,an adjustable dynamic range quantization circuit for laser gas sensor is designed in this paper.The adjustable dynamic range quantization circuit adopts a FLASH-SAR two-step hybrid structure based on SAR ADC to switch the working state according to the input signal of the sensor so as to reduce the accuracy redundancy of the signal due to different types of gas with different effective range The SAR ADC uses the segmented capacitor structure with Vcm-Based switch control method to reduce the power consumption and chip area,and the comparator uses a four-stage pre-amplification and Latch dynamic latch comparator structure to meet the requirement of system accuracy and speed.The FLASH-ADC adopts the coding method of thermometer code-Gray code-binary code to eliminate the quantization error,and uses subtraction circuit to make a difference between the input signal and the reference signal,and an improved gate-volatage bootstrap switch is proposed which is better performance to the traditional one.The quantized circuit designed in this paper realizes circuit design,layout design and post-simulation verification under UMC 0.11?m 1P7M process.The quantization circuit can realize switching of 500KS/s 12-bit and 238KS/s 16-bit in the range of 0?2V.The simulation result shows the DNL of 12-bit SAR ADC is-0.067LSB?0.93LSB,INL is-1.3LSB?1.3LSB,SNDR is 64.5316dB,ENOB is 10.4261-bit,SFDR is 81.4334dB,and THD is 79.995dB.The total layout area is 1335?m*600?m,and when the analog circuit supply voltage is 3.3V and the digital circuit supply voltage is 1.2V,the overall circuit power consumption is 6.567mW. |
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