Design Of A High-Precision Digital Temperature Detection Circuit

With the development of global Internet of Things, temperature sensor, as a basis element of IOT, is increasingly widely applied.Family of things, Moreover, in order to meet the demands of the market in many aspects, the requirements of temperature sensor are expected high precision, low power consumption, low cost, light and so on.At this time, integrated temperature sensor perfectly combine with integrated circuit technology. As it can be integrated on one chip, it is suitable for mass production and its cost is low, the precision can meet the requirements and power consumption, and also well meet the application of IOT.In this thesis, a high precision Digital CMOS temperature detection circuit is designed,which is based on TDC circuit, relative to the traditional ADC circuit, the former can achieve lower power consumption and smaller area under the same precision.The circuit designed is composed of temperature to pulse-width interface circuit and TDC circuit.For interface circuit module, this paper analysis of the temperature sensitivity principles of integrated resistance, MOS, PN junction, on the basis of which, MOS tube and Poly resistance as a temperature sensing element are adopted.The corresponding PTAT and CTAT delay are achieved by the interface circuit.In order to get the relationship between the height of the first order linear delay and temperature, the method of second-order coefficient of temperature compensation is adopted.For TDC quantification module,at first the TDC of vibration type temperature compensating voltage control loop structure is used, the structure with temperature compensation provide voltage-controlled voltage offset, the ring frequency behaves poor temperature stability.Thus DLL voltage-controlled ring mode structure of TDC is adopted, which voltage is controlled by DLL, ring vibration frequency of temperature stability is improved a lot.Based on TSMC 0.35?m CMOS process, with the help of the Spectre and Virtuo, system architecture, layout design, and circuit simulation are all completed.Finally,the circuit is verified in the MPW flow.Test results show that,where the power supply voltage is 3.3V, temperature measuring range is -40? to 100?, the resolution is 0.17?, the absolute error is less than 1.5?.which meet the design index requirements.