| CMOS temperature sensor,which has simple-structure,low-cost,low-power,small-area,is widely used in chip temperature test,medicine instrument and RFID applications.The development of CMOS temperature sensor is also pushed by it’s wide range of applications,so research of CMOS temperature sensor with higher-accuracy,less-power,less-cost becomes an important subject.In this paper,three main works completed.1、The importance of sensing technology,the application value of sensors are firstly studied by referring to a large amount of literature data.Then combined with VLSI technology and temperature measurement technology,the research progress and achievements of CMOS temperature sensor in recent decades at home and abroad are stated and summarized.The requirement of CMOS temperature sensor which is applied in SD/MMC controller is analyzed.2、The theory of CMOS temperature sensor is introduced in detail.The basic characteristics of transistors under CMOS process are introduced firstly.Then the parameters of MOS transistors and bipolar transistors vary with temperature are analyzed.The temperature sensors which exploit the threshold voltage、the base-emitter voltage of bipolar transistors or the oscillators are introduced in detail.Last,the ADCs and counters are introduced as a way of converting temperature to a digital output.3、A RC oscillator-based temperature sensor is designed.All the sub-circuits are analyzed and simulated in detail.The proposed CMOS temperature sensor comprises a RC oscillator with a counter and thereby reduces the circuit complexity.The circuit has simple-structure,low-voltage,software-controlled and fast-start.Based on the TSMC 0.18 μm CMOS process model library,the proposed CMOS temperature sensor has been simulated by Cadence Spectre simulator.The fabrication results show that its accuracy can reach ±3 ℃ in the temperature range of-10~80 ℃.All performance satisfies the specification. |
