Design And Optimization Of Integrated Readout Circuit Of Multi-functional Sensors For Detecting Temperature, Humidity And Pressure

Monitoring of temperature,humidity and pressure in the external environment is of great importance in military and civil fields.However,traditional multi-functional sensors have many disadvantages such as large volume and discrete components.Monolithic integrated temperature-humidity-pressure multi-functional sensor can realize the multi-sensor integration,miniaturization and low-power consumption,which holds a tremendous potential.In this paper,a integrated readout circuit of temperature-humidity-pressure multifunctional sensor was designed and optimized.The readout circuit mainly includes signal processing circuit of temperature sensor,humidity sensor and pressure sensor,and an onchip integrated analog-to-digital converter(ADC).The readout circuit realizes digital signal output,and the readout circuit has many characteristics such as high sensitivity,high integration and wide measurement range.The main research contents are as follows:1.The corresponding signal processing circuits of three sensors were designed and optimized.Different physical quantities were converted into voltage quantities by signal processing circuits,and system-level simulation was carried out.For the temperature modules,a second-order curvature compensated bandgap reference power supply was designed.The temperature coefficient is 17.53ppm/°C.The temperature sensitivity of temperature signal processing circuit is 21.6 mV/K,and the linearity of output voltage is 99.8%.For the humidity module,a new differential switched capacitor circuit structure was adopted.Two operational amplifiers were used for time-sharing sampling to make the signal output continuously,and the output voltage showed good linearity.For the pressure module,the signal was amplified by a three-opamp instrumentation amplifier structure.The optimized design made amplifier gain adjustable The power supply rejection ratio(PSRR)is 110.8 dB,which meets the design requirements.2.An on-chip integrated ADC for readout circuit was designed.The on-chip ADC circuit is a chip-integrated single-slope ADC.In order to optimize ADC structure and reduce chip area,a low power current storage unit was used instead of a complex register.The ADC accuracy is 14 bits,the corresponding INL is +0.9LSB/-0.85 LSB and the DNL is ±0.6LSB.The noise characteristic is significantly reduced.3.The layout drawing of the readout circuit and the test of the chip was completed.The test results of the chip show that the signal processing circuits and on-chip ADC work steadily.The test results are consistent with the simulated results,and each design meets the requirements of the indicator.