The Research And Design Of Integrated Temperature Sensor For Self-powered Pavement Surface Monitoring

With the wide application of asphalt pavements,the damages caused by vehicle overload,natural weather and geology are becoming more and more serious.Data monitoring inside asphalt pavements becomes increasingly important,and temperature is the most important one of data information in pavement monitoring.Compared with the traditional discrete temperature sensor,CMOS temperature sensor has the advantages of low cost,low power consumption,wide detection range and easy integration with self-powered systems.It has great application value in road environment monitoring.In order to improve the level of road construction and maintenance management,the traditional pavement detection methods are time-consuming,labor-intensive,and inefficient,and it is difficult to achieve the shortcomings of periodicity and real-time detection.A simple and practical,low-cost self-powered asphalt pavements sensor system solution with lots of data verified repeatedly was proposed.The key technology of temperature sensor was researched and analyzed for self-powered asphalt pavements sensor system.The circuit design and simulation were completed by UMC 0.18 ?m CMOS technology.The main research contents are as follows:(1)Analysis and design of the temperature sensing circuit.The key circuits designed and completed include: a bandgap voltage source using a folded cascode two-stage op amp;a wide-output interval temperature detection circuit based on the bipolar transistor temperature sensing principle at different current densities;2MHz clock-controlled Relaxation oscillator.(2)Analog-to-digital converter design.A 10-bit segmented capacitive successive approximation register ADC was designed,as well as a first-order sigma-delta ADC based on a 13-bit D flip-flop cascade counter.(3)The system simulation of the temperature sensor were completed for different analog-to-digital conversion methods.The system simulation results show that the successive approximation register type temperature sensor has a temperature detection error of ±2.6 °C and a system power consumption of 2.45 mW in the range of-40 °C to 80 °C.The temperature detection error of the ?-? type temperature sensor in this temperature range is obtained.The system consumes 1.2mW at ±0.82°C.The successive approximation registertype temperature sensor has a faster conversion speed than the ?-? type temperature sensor,but the ?-? type temperature sensor meets the design requirements in terms of accuracy and power consumption,and the temperature detection requires low speed for the analog to digital converter.(4)The layout of the ?-? type temperature sensor was designed and the chip area was evaluated.The results show that the overall area of the ?-? type temperature sensor is 0.287 mm × 0.246 mm.