Research On High Accuracy CMOS Temperature Sensor Chip Based On Bandgap Voltage

In recent years,with the rapid progress of science and technology,more and more function module can be integrated in the chip,the function of the electronic product becomes more rich,the volume is being reduced gradually,and the power consumption is increasing gradually,so the temperature of the system can not be ignored.As the temperature abnormality affects system function,a temperature sensor is usually integrated into many highly integrated systems to detect the temperature change within the system,which play an important role on protection of the system functions.At present,the research progress on temperature sensor chip is gradually accelerated in China,and the directions of high precision,low power consumption,intelligence,etc.They have become the current research hotspot.Based on the research status of temperature sensor at home and abroad,a high-precision CMOS temperature sensor chip was studied and designed with SMIC 0.35 ?m CMOS process in this paper.A longitudinal parasitic PNP transistor was used to temperature sensing element.The voltage VBE of PNP transistor base-emitter is inversely proportional to temperature.Two PNP transistors base-emitter voltage difference ?VBE which bias at a certain current ratio is proportional to temperature.Those characteristics were used to produce negative temperature coefficient current Isource and positive temperature coefficient current Isink,a temperature sensing circuit with bandgap reference temperature sensing structure was designed;Dynamic matching technique were adopted to decrease the process mismatch which influence positive temperature coefficient voltage ?VBE.The nested chopping technology was adopted to reduce the operational amplifier offset voltage and ficker noise that influence negative temperature coefficient voltage VBE.In order to get the digital output that represent measuring temperature,a high-precision ?-?ADC was designed to quantify the negative temperature coefficient current Isource and positive temperature coefficient current Isink accurately.Based on Cadence software platform,the circuit module design of temperature sensor chip was completed,and AMS and Spectre were used to complete simulation verification.When the power supply voltage is 5 V and the working temperature is-25??100?,the digital-analog hybrid simulation of the whole chip circuit is carried out at each process corner.The temperature measurement accuracy is-2??1?.Virtuoso and Calibre were used to complete the overall layout design of the temperature sensor chip.The total area of the final layout is 1253 x 1145?m2.The post-simulation verification of the whole circuit of the chip with AMS was done.The temperature measurement precision of the post simulation is-2??1.5?.The output of is digital,and its compatibility is good.The high-precision CMOS temperature sensor chip can be used in fields of consumer electronics,household appliances,industrial control,etc.