Design Of High Precision Bandgap Reference Source Based On Chopper Modulation

Reference voltage source plays an important role in analog circuit,digital circuit and mixed signal circuit.For any system,a stable reference voltage is indispensable.With the development of science and technology,portable electronic devices have been widely permeated into People's Daily life.Circuit modules such as ADC,DAC and power management chips are the basic elements of these devices.The performance of reference source will affect the working state of the above modules,so more strict design requirements for bandgap reference are proposed.In this paper,a high-precision bandgap reference voltage source is designed.Two methods are used to reduce the temperature coefficient:IPTAT2 current compensation method and high-order curvature compensation method.By comparing the performance parameters,the high-order curvature compensation method is finally selected.Considering that the bandgap reference needs to possess a high enough interference suppression ability of the power supply voltage,a negative feedback form of pre-stabilized circuit structure is set up,through which the whole power supply of the core circuit is supplied,so as to greatly improve the power rejection ratio.Secondly,the reasons for the deviation of the reference output are analyzed,including linear error and nonlinear error.In order to reduce the linear error caused by the process mismatch,a two-point resistance repair and adjustment method is proposed.Then,based on the principle of modulation and demodulation,an operational amplifier and a notch filter with a chopper module are designed to greatly reduce the nonlinear error caused by opamp offset voltage Vos and low frequency 1/f noise.In this design,SMIC 0.18?m process and Cadence Spectre platform were used to complete the circuit pre-simulation test,layout drawing,parasitic parameters extraction and post-simulation.The simulation results show that the temperature range is-40??125?,the power supply voltage is 2.5V?4V,the temperature coefficients are all less than 5ppm/?,the power supply rejection ratio is up to 110dB at low frequency,the output reference voltage is 1.1032V,the static current power consumption is less than 100?A under the effect of the full modification and modulation code.Compared with the standard output voltage,the error is-1.5%?1.28%,and the accuracy can be controlled less than±0.6%when the proper modified code is selected.