Development Of A Linear Regulator With A Low Noise And High Stability

With the rapid development of the integrated circuit industry,electronic products(such as mobile phones,smart speakers,tablets,electric balance cars,etc.)are becoming more and more intelligent and diverse.To a certain extent,the living standard of people have been improved.At the same time,the requirement of consumers for charging speed,standby and battery life,and volume of electronic products are also growing.Power management chip is considered as a core component of electronic products,which directly affects the performance of electronic products.Currently,the chip occupies a large market share,therefore designers are making efforts to design the chip in the direction of low noise,low power consumption,high power rejection ratio and high integration.In this paper,the author designs a low noise and high stability linear regulator.In order to increase the temperature stability of the reference output voltage,and design a segmented temperature compensation circuit,we develop a high performance piecewise linear compensation CMOS bandgap reference.Besides,we add a noise reduction circuit to the output of the bandgap reference source and provide the ideal reference voltage for the error amplifier,and the clamp output is used in the first stage of the error amplifier that select PMOS as the input stage to achieve the purpose of reducing the output noise of the linear regulator according to the characteristics of the MOS transistor.In the meantime,the buffer stage output is used in the output stage of the circuit to improve the driving capability and response speed of the linear regulator,and the frequency compensation technology is used to compensate the loop system to improve the stability of the linear regulator.There are five essential designs about the chip.Firstly,the under-voltage protection circuit is designed to prevent the circuit from working in an abnormal state and reduce the power consumption of the circuit.Secondly,a current limiting protection circuit is designed to limit the maximum value of the load current to prevent the circuit from being burnt out when the load current exceeds the design value.Thirdly,an over-temperature protection circuit is designed to ensure that the linear regulator is not damaged when the operating temperature of the linear regulator rises and exceeds the maximum temperature for normal operation of the circuit.Fourthly,the chip also has the function of enabling shutdown.Finally,the layout design is carried out.The top-level simulation of the linear regulator is based on the Hua Hong 0.35?mBCD process.Simulation verification is performed under different voltage and full process.The simulation results show that when the input voltage is in the range of2.8V~5.5V,the output voltage is 1.8V,and the output voltage line regulation is less than 0.12%/V.The load regulation rate is less than 0.15mV/mA,and the maximum output current is greater than 100 mA,and the lowest output noise is 15.6?Vrms.when the chip operates at low frequency,the power supply rejection ratio is 74.3dB.Performance of all protection circuits and enabled shutdown circuits meet design specifications.