Design Of Ultra-low Temperature Drift Integrated Voltage Reference Sourc

The voltage reference source is an important module in electronic systems,which is widely used in digital-to-analog converters(DAC),analog-to-digital converters(ADC),DC/DC,automatic control systems,and other scenarios.Input voltage range,output voltage accuracy,and temperature coefficient are the key indicators of the reference source.Wide input voltage range,high precision,and low-temperature drift have always been the goal of this kind of chip.With the expansion of the operating temperature range and the improvement of the accuracy requirements of the electronic information system,the integrated voltage reference source for ultra-low temperature drift becomes more and more important.This paper introduces the development history of ultra-low temperature drift reference sources,the research status and demand of the domestic and foreign markets,and the traditional model.Using the Brokaw bandgap reference model,an integrated voltage reference source with a wide input voltage range and ultra-low temperature drift is designed.After analyzing the parameter requirements,the research objectives and index parameters of the ultra-low temperature drift reference source are formulated,which mainly focus on the two main parameters of the ultra-low temperature drift coefficient of the output voltage and the wide input power supply,as well as 13 main parameter indexes.In the circuit design part,the bias circuit uses the improved base-emitter voltage as the current source,the current mirror is used to supply current to other modules,and the feedback is connected to the clamp op-amp to improve the input voltage range of the circuit.The input stage of the two-stage op-amp used in the circuit is improved to increase the gain and reduce the offset.The core bandgap reference circuit is designed based on the Brokaw model,and the second-order compensation of the temperature drift of the reference is carried out by the compensation method of different resistance temperature coefficients.The operational amplifier adopts a two-stage op-amp structure,and the input stage is optimized to achieve high gain and low offset.The output stage of the reference source adopts a class-B output structure,which can effectively improve the gain and obtain a small node impedance.In addition,it can provide sufficient driving ability.To ensure the high precision and ultra-low temperature drift of the output voltage of the reference voltage source,the tuning resistor is designed in the key branch,and the detailed laser tuning scheme is formulated.After confirming the parameters,based on the 40 V BJT process of a domestic company,the integrated voltage source circuit of ultra-low temperature drift is designed and verified with Cadence as the simulation platform.The simulation results show that the temperature coefficients of 2.5 V and 3 V output voltages are less than 3ppm/℃ in the working voltage range of 4.5 V ～ 36 V.The linear adjustment rate of 2.5V output is 0.0662 μV/m A,the linear adjustment rate of 3 V output is 0.0824 μV/m A,and the load adjustment rate,short circuit current,output resistance,and other parameters of the two output voltages meet the parameter requirements.After the layout design and verification of the chip are completed,the post-layout simulation is carried out,and the post-simulation results of each index parameter meet the expected requirements.