The Design And Implementation Of A0 High Precision And Low Noise Rail-to-Rail Operational Amplifier

Rail-to-rail operational amplifiers allow input and output signals to be offset very close to the positive and negative supply voltages.The amplifier accepts input signal swings,which may slightly overload the rails at the input?the voltage signal is greater than the rail-to-rail?.It is mainly used in precision signal system transmission amplification occasions,and is used in remote communication equipment and wearable smart devices.It has a very important position,especially in the development of new generation communication systems.Lightweight,miniaturized and highly reliable development must take such basic circuits as an important support.The thesis introduces the theoretical basis of rail-to-rail op amps.The research focuses on high-precision(V_OS<1mV)and low noise?en?10nV/?Hz?parameters.First,the noise advantages of BJT devices are analyzed,and the noise model of the differential amplifier circuit is analyzed.Secondly,it analyzes the main processes and circuit structures that affect low offset parameters,and clarifies the application scope and advantages and disadvantages of fuse?anti-fuse?trimming and laser trimming.This article focuses on the realization of rail-to-rail op amps.In circuit design,a two-stage op amp structure is used.The input stage adopts the input differential pair mode.In order to achieve constant transconductance,a mirror current matching method is adopted.The bias circuit uses a current mirror mode to establish a current operating point and form a stable constant current source.High-gain stage with stable loop using Miller compensation.In order to fulfill the requirements of op amp accuracy and driving capability,a Class AB output structure is designed to compensate the inner-loop feedback effect through capacitance to form a fast feedback channel and suppress output ripple.Aiming at high-precision characteristics,design laser trimming and circuit adjustment schemes to improve the success rate of tape-out.This thesis selects a domestic company's 40V bipolar process to complete the low-noise bipolar transistor process design and optimize the process flow.Detailed simulation verification based on the Cadence platform.The simulation results show that the offset voltage I_OS=1.05?V,slew rate SR=5.67V/?s,gain bandwidth product GBP=3.2MHZ,common mode rejection ratio CMRR=133dB,and voltage noise density:e_n=4.21 nV/?Hz,gain=122dB.Completed the layout design of the op amp,In this thesis,the package and test design of rail-to-rail op amps are adopted.The F08 type ceramic package is used.The vacuum alloy welding technology is used to eliminate the void rate and improve the quality and reliability of the packaged product.The Eagle364 integrated circuit test equipment was used to complete the development of various key parameter test circuits.The nV level noise param/eter test was researched.The product was packaged and selected for key parameter testing.The final verification results meet the design needs.