Design And Fabrication Of A CMOS Linear And Thermal-Shutdown Temperature Sensor

With the feature size of integrated circuits becoming smaller and smaller,chip density increases rapidly.At the same time device density,energy density are also increasing.The greater power consumption,the more slowly heat distributs to the surrounding environment and the more significantly chip temperature rises.Research data shows that when chip temperature increases every 1℃,the drive capacity of MOSFET will drop about 4%,connection delay increases by 5%and integrated circuit failure rate doubles.Meanwhile,on-chip temperature detecting sensor becomes more and more popular because of the various types of portable electronic products. To guarantee the integrated circuit performance and improve chip reliability, designing of an on-chip linear and thermal-shutdown temperature sensor with simple structure,easy to transplant and can cut off the power circuit when too hot meanwhile show the local temperature is extremely important,this is particularly prominent in high-power circuits.The linear and thermal-shutdown temperature sensor is designed and fabricated with 0.6μm standard CMOS process provided by CSMC.It can cut off the power supply of the overheating module according to the setting temperature and also show that circuit's local temperature.It realizes overheating protection and real-time temperature detection.Its greatest feature is that the shutdown temperature can be set by an external adjustable resistance.The thermal-shutdown part is composed of PTAT module,reference module,a buffer and comparator module.PTAT output voltage is defined as proportional to the thermodynamic temperature.Experimental results yield an output PTAT voltage sensitivity 10mV/℃and good linearity(maximum dispersancy is 1.6%)over the range of 30～130℃.The PSRR of reference is 37.5dB and the temperture coefficient is 137ppm/℃.Shutdown temperature can be set by an exterior resistor and under 85℃the gap between simulation and experimental result is less than 5℃while up to 10℃over 85℃.In the power supply range of 4.5～5.5 volt,fluctuations of the output port of PTAT temperature measurement module named Vptat₂ is 35mV,representing a nominal value of 0.89%.Sensitivity of output Vptat₂ is 9.88 mV/℃over 26～55℃and have good linearity.But during 55～80℃,performance has declined.The sensor we talked above has simple structure,easy to transplant and can be applied to many fields such as LED illuminance drive and power supply management circuits with temperature detecting and thermal-shutdown.It also constitutes power device modules with self thermal-shutdown when packged with MOS power devices.