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基于标准CMOS工艺设计了一款集成热真空传感器、运算放大器、逐次逼近型模数转换器(SAR ADC)、数字信号处理电路的传感器系统。工作在恒电流模式的传感器,气压敏感区间为1～105Pa。运算放大器(OPAMP)的输入级采用互补差分对获得轨至轨的共模输入范围。为满足精度要求,对SAR ADC中数模转换器电容阵列进行优化设计,并采用输出失调存储技术消除比较器的失调电压。数字电路采用查表法将电压信号变换为气压值。结果表明:运算放大器能无失真地驱动200Ω电阻,模数转换器的有效位为9.5 bit。运算放大器、模数转换器、数字信号处理电路性能良好,满足传感器系统要求。
Based on the standard CMOS process, a sensor system integrating thermal vacuum sensor, operational amplifier, successive approximation analog-to-digital converter (SAR ADC) and digital signal processing circuit is designed. Work in constant current mode sensor, pressure-sensitive range of 1 ~ 105Pa. The OPAMP input stage uses complementary differential pairs to achieve rail-to-rail common mode input range. In order to meet the accuracy requirements, the design of digital-to-analog converter capacitor array in SAR ADC is optimized and the offset voltage of the comparator is eliminated by the output offset storage technology. The digital circuit uses the look-up table method to transform the voltage signal into the pressure value. The results show that the op amp can drive a 200Ω resistor without distortion. The effective bit of the A / D converter is 9.5 bit. Operational amplifiers, analog-to-digital converters, digital signal processing circuits perform well to meet sensor system requirements.