Design Of A High Precision And Low Noise LDO Circuit

At present,portable electronic products have penetrated into our lives and made our lives colorful.But they have a common drawback that is the flutuation of the external power can cause some of the internal chip functions to fail.In order to resolve this contradiction,power management chips are usually used,which convert the external power supply into a stable and strong anti-interference power supply,and then drive the internal circuit.Under the above background,the paper designs a high-precision,low-noise and low-dropout linear regulater(LDO)circuit by designing a dual trim circuit,a temperature compensation circuit,and a high-gain,low-noise amplifier.The LDO circuit designed in this paper is divided into five sub-modules:bandgap reference circuit,error amplifier(EA),power stage circuit,over-temperature protection circuit and frequency compensation circuit.First of all,the design of the bandgap reference circuit based on the Brokaw bandgap reference circuit structure has better noise performance than other reference circuit structures.By designing a temperature compensation circuit and a digital trimming circuit,the impact of temperature and process deviation on the accuracy of the reference circuit output voltage is reduced,and the accuracy of the overall LDO circuit is indirectly improved;an RC filter is added to the output of the reference circuit to filter out the high frequency noise of the output voltage of the reference circuit.On this basis,the design of other sub-modules of the LDO is carried out,and the structure of the folded cascode amplifier is used for the design of the EA,and a negative feedback resistor is added to the source of the current mirror as the amplifier load to reduce the noise of the amplifier.Use trimming technology to design power-level circuits,trim feedback resistor mismatches,and improve the accuracy of LDO circuits.Design a temperature compensation circuit to avoid damage to the chip caused by misoperation.The adaptive buffer structure is used to design the frequency compensation circuit,which makes the stability of the LDO feedback loop more superior.Based on TSMC 180nm process,using Cadence software to simulate and verify the designed LDO circuit,under 5V power supply voltage,quiescent current consumption is0.454m A,and the temperature coefficient within the range of-40??85?is0.2996ppm/?,linear adjustment rate is 0.0036%/V,load adjustment The rate is0.03278%/V,the Monte Carlo accuracy is±0.8%,and the final accuracy is±0.83%,the low-frequency power supply rejection ratio is 80.03d B,and the integrated noise in the range of 10?100k Hz is 49.97?V_rms,which meets high precision and low noise design requirements for LDO circuits.On this basis,the layout design and post-imitation of the LDO circuit are carried out,so that the designed LDO has more practical application value.The post simulation results are:the linear adjustment rate is 0.004%/V,the load adjustment rate is 0.0334%/V,the temperature coefficient in the range of-40??85?is0.312ppm/?,the Monte Carlo accuracy is±0.87%,and the final accuracy is±0.90%;the low frequency power supply rejection ratio is 78.94d B,the integrated noise in the range of 10?100k Hz is 49.79?V_rms,and the previous simulation is basically the same and meets the design requirements.