环境噪声抑制的红外接近传感器设计

分析红外接近传感器的工作原理，针对红外接近传感器容易受到环境噪声影响而发生检测错误的问题，提出一种高效的环境噪声抑制方法．该方法通过光学镀膜滤波和基于时序控制的数字模拟混合减法电路，分步滤除环境噪声，达到准确接近检测目标的目的．设计了相关传感器电路，可以在太阳光或灯光光照度低于4000lx，温度低于85℃的环境下，实现25cm范围内的物体接近程度的准确测定．在相同工艺下，通过Spec-tre进行仿真，结果表明：该传感器在给定的噪声环境中工作与无环境噪声的理想情况相比，最大误差不超过1％．所设计电路已在0．35μm3VCMOS工艺下投片验证，结果满足设计指标．

Design of an infrared proximity sensor with environment noise suppression

Fundamentals of infrared proximity sensor was proposed.The infrared proximity sensor cannot sense proximity correctly with the effect of environment noise,such as the interference of sunlight,light and temperature change.A kind of highly effective method of environment noise suppression was proposed based on the problem,which employed optical filming filter and sequential controlling digital-analog mixed subtraction circuit to remove environment noise step by step,achieving the purpose of accurate proximity sensing.Moreover,the sensor circuit was designed,which could sense the proximity of object at a distance up to 25 cm away from the sensor under the environment of the sunlight or the light illumination lower than 4 000 lx and temperature lower than 85 ℃.The designed circuit was verified by Spectre simulation in the same process.The simulation results show that under the given noise environment the sense error is less than 1%.The designed structure is implemented in 0.35 μm 3 V CMOS process.