Design Of CMOS Temperature Sensor Circuit

In recent years,temperature has become a more important parameter in chip design.This is because,with the development of the VLSI,the characteristics of the CMOS chip technology are decreasing and the integration degree is increasing year by year,which leads to the increase of the power density in the integrated circuit and the reduction of the reliability of the system.For this reason,on chip temperature detection becomes more and more important.In the case of temperature rising,the performance of components in CMOS process is more serious.Therefore,with the rise of temperature,the study of the change of components'performance is also being more important.The case researched and designed a temperature sensor chip.The chip is made up of CMOS elements and is used to sense the chip temperature.The output is eleven bit digital signal.The chip is designed through the linear reduction of the threshold voltage of MOSFET with the increase of temperature.In this paper,the threshold voltage and mobility of MOSFET are modeled and deduced.The temperature range of the linear change of the threshold voltage and the change of MOSFET mobility with the temperature are determined.Based on this,the change of the threshold voltage is chosen as the temperature sensing principle to design the temperature sensor.At the same time,compared with the traditional chip of transistor base emitter voltage difference?V_be as the basic physical quantity of temperature measurement,the working current is small,the cost of the process is low,and it has higher applicability in the CMOS chip.The circuit consists of three parts:threshold voltage acquisition circuit,VCO and counting circuit.The threshold voltage acquisition circuit is used to ensure that the output voltage is linearly changed in the working range of temperature,and that the nonlinear output changes are not caused by the change in the working area of the MOSFET in the circuit.The VCO is composed of the inverter,which is used to change the threshold voltage to the frequency signal to facilitate the next level circuit.The signal is processed;the counting circuit is used to count the frequency signals,and the eleven bit digital output is obtained.The circuit uses the power supply voltage of 1.8V,and uses Cadence software and tsmc018Technology Library to simulate the design.After the simulation results,the precision of the circuit is 0.15 degrees C,the error rate is 12%,the chip power is less than 10 W,and the chip size is 300?m×590?m in the temperature range of 0?to 150?.The designed circuit chip is expected to be applied to portable instruments.