The Design And Realization Of High Precision Temperature Sensor

With the advancement of process manufacturing technology and the rapid replacement of electronic products,the application systems are becoming more and more complex,focusing on the electronics sensors required for dedicated high-precision temperature sensors,in consumer electronics,medical equipment and industrial control.The field is indispensable.The rapidly growing demand for higher performance temperature sensors makes this study of temperature sensors important.This paper focuses on the design technology of high-precision temperature.Compared with traditional temperature sensors,the architecture is simple,low-power,and easy to integrate.It has a wider application prospect.This paper focuses on the temperature sensor design technology.The paper first summarizes the current status and trends of temperature sensors,and describes the advantages and characteristics of temperature sensors.The traditional temperature sensor is mainly composed of two parts,one is the temperature sensing module,and the other is the analog-to-digital converter ADC,which converts the analog voltage or current linearly related to temperature into a digital quantity.Because the triode's?VBE(PTAT voltage)has good linearity and is not sensitive to the process,it has very good repeatability.Therefore,many temperature sensors are used as modules for temperature sensing.This article also uses the method of sensing temperature by?VBE,but this paper is very different from the traditional way when the voltage obtained by induction is converted into digital.The temperature sensor designed in this paper first generates a band gap reference voltage and a positive temperature coefficient of PTAT(proportional to absolute temperature).Then use two identical voltage-frequency conversion circuits to convert the PTAT voltage and the reference voltage into frequency respectively.Finally,the ratio of the PTAT voltage to the reference voltage is obtained by counting two 13-bit counters,thereby obtaining the temperature value and the temperature resolution.The rate can be adjusted by adjusting the number of bits in the counter to obtain a temperature of any resolution.By analyzing various non-ideal factors in the temperature sensor,Chopper technology,base current compensation,and Trimming calibration circuit are used to eliminate the influence of non-ideal factors and improve the temperature measurement accuracy.The temperature sensor designed in this paper adopts CSMC 0.25um BCD process.With Cadence Spectre simulation tool,the power supply voltage is 3.3V.Six temperature points are selected to verify the whole temperature sensor circuit.The designed temperature sensor is calibrated to achieve±0.2°C accuracy and 0.08°C resolution over the-40°C to 125°C temperature range.The chip consumes 106uA at room temperature and has an average temperature conversion time of 15ms.The chip area is 0.15 mm~2,which meets the design specifications.