Research And Design Of CMOS Integrated Temperature Sensor

Technology can not develop without measure. Measure aims to acquire the physics or chemistry data about the object, then the data will be used to estimate or control the object, and the parts of an apparatus accomplishing this functional is called sensor. Sensors have abroad application in domains of industry, agriculture, science research, and aviation. And as foundation of many technologies, sensor has been regarded and developed vigorously in many developed countries.This thesis focuses on the study and design of an integrated temperature sensor based on the standard CMOS process. This Temperature sensor can be used for the accurate measurement of the temperature or the ambient temperature, and it has the advantages of small size, wide measuring range and high precision. The major design of this thesis includes the research of the types of temperature sensor and the different measurement methods, the research of theΣ-Δconversion technology, the research and design of the whole system structure of the temperature sensor and every function module of the temperature converter, and the research and design of the digital filter. In this thesis, the temperature sensor can be divided into two parts: integrated temperature converter and digital filter. The integrated temperature converter is composed by temperature component, acquisition circuits of the complementary to absolute temperature and the proportional to absolute temperature, 1.2V and 0.6V high precision bandgap voltage source, voltage comparator, CMOS switch circuit and output buffer module, and etc. The digital filter consists of CMOS asynchronous counter, D trigger and D latch, and narrow pulse circuit.This temperature sensor is designed and simulated by Virtuoso and Spectre which are products of Cadence. All the device models are offered by 0.35μm CMOS process module of TSMC. The working voltage of the temperature converter is 3V, maximum power consumption is less than 0.3mW, working frequency is 400KHz with 50nf external capacitor, and it can measure the temperature ranging from–20℃to 60℃, and the minimum accuracy is 0.2℃. The rate of temperature change of proportional to absolute temperature is 0.01439μA/℃, and of the complementary to absolute temperature is 0.03775μA/℃. The output voltages of bandgap voltage source are 1.2V and 0.6V, and the temperature-adjusted rates are 0.001375mV/℃and 0.004375mV/℃. About the operational amplifier of the bandgap voltage source, its open-loop gain is as high as 95dB, phase margin is 60°, unity gain bandwidth is 8.6MHz, PSRR is 79dB, and the offset voltage is 278.05μV. The gain of the voltage comparator is 76.5dB, and it begins to fall down at the frequency of 850KHz. After simulation all parameters have met the design requirements.