Design Of Digital Integrated Temperature Sensor Based On BCD Process

With the development of science and technology,as an indispensable sensor in the field of consumer electronics and industrial control,more and more attention has been paid to temperature sensors and the demand for high performance temperature sensors is also increasing.Nowadays,the research on temperature sensor is developing towards digital,low power consumption and high precision.Because of their low power consumption,small area,digital output and integration with other circuits,integrated temperature sensors are widely used.The base-emitter voltage V_BEof a transistor has a negative temperature coefficient relationship with temperature at a certain bias current.And in different bias power flow,the two transistor's base-emitter voltage difference?V_BEvaries with temperature is positive temperature coefficient relations.The?V_BEis amplified by the related technology,so that the amplified voltages??V_BEand V_BEcan form a reference voltage.Through the Sigma-Delta ADC to quantify these two voltages associated with the temperature of??V_BEvaries with the V_BEvaries.Then the output of the modulator is a digital quantity related to temperature.These temperature-related digital quantities can be obtained by linear processing.Transistors can be used as temperature sensors for temperature sensors in the BCD process and it also can be integrated with other circuits on a single chip.All kinds of non-ideal factors in transistors and modulators will lead to errors in temperature output.After analyzing relevant error sources in the circuit,we adopt the current offset structure of the specific structure and dynamic matching technology to reduce the effects of the finite gain in transistors and the non-linearity of the output voltage of the electrical loss pair temperature detection unit.Against the non-ideal factors in the modulator,and the chopper structure in the design of the op-amp,to reduce disturbance voltage and 1/f noise effect the performance of the modulator,complementary CMOS switch adopted to reduce harmonic distortion.Based on Huahong 0.35?m process,the design and simulation of PTAT bias current,gain bootstrap amplifier,chopper operational amplifier,dynamic latch comparator,dynamic matching and other circuits have been completed,and the mapping of the territory have also been completed.Design of digital integrated temperature sensor's scope of work for-45?¹25?,the resolution is about 0.1?,the power consumption is about 1.8 mW.Modulator of the design of the simulation shows that the precision can reach 16 bit,it is fully able to meet the requirements of temperature sensor resolution of 0.1?.The whole circuit simulation results show that the maximum error is about±0.6?.