Design Of High Precision Bidirectional Current Shunt Monitor

Current shunt monitor chip plays an important role in today's complex integrated circuit system.By monitoring the amount of current in electronic equipment,it can be judged whether the circuit is working normally,so that the working state of the circuit can be monitored in real time to avoid instantaneous excessive current and damage to electrical equipment.Therefore,it is necessary to design a high-performance current shunt monitor to detect accurately the current flowing to the load.In this thesis,a novel bidirectional current shunt monitor is designed.The circuit can realize accurate bi-directional current detection in the range of input common mode voltage-4 ? 4 V,and can detect the current flowing through the detection resistor on the premise of ensuring the accuracy.Its core circuit is composed of two comparators,three error amplifiers,some current mirror modules and resistors.One comparator is used to determine the current direction,the other is used to determine the input common mode voltage range,so as to ensure that the circuit can work normally under the condition of positive and negative input common mode voltage.The dissertation has completed all the work from the determination of the system architecture,the analysis of the circuit structure,and the calculation of the circuit parameters.The overall circuit uses the SMIC 0.18 ?m CMOS process.After completing the analysis and design of each sub-module and overall module,the overall circuit was simulated and verified by spertre,and the layout was verified by DRC and LVS using Calibre.The layout design and layout also met the process design requirements.It can be verified through simulation that when the input(Vin)is 5 ? 16 V,and a 5 V(Vdd)is generated by the LDO,the current shunt monitoring is performed when the common-mode input voltage changes within the range of-4 to 4 V.The device can accurately detect the voltage difference of 4 ? 40 m V and can amplify it by 100 times for output.The gain error of the system is less than 0.65% in the whole temperature range(-25 ° C to 100 ° C).The CMRR of the system is simulated at different process angles(tt,ss,ff,sf,fs),and the output results are all greater than 130 d B.In addition,Monte Carlo simulation is also performed on the overall circuit.Through simulation verification,the output results can accurately amplify the detected voltage by 100 times for output.Simulation results show that the detection voltage and output voltage of the circuit have a good linear relationship.The test results show that the chip can work normally in different situations and can achieve the expected designed function.In summary,this article has carried out relevant research on the design of high-precision bidirectional current shunt monitor chips,and discussed the principles and methods from circuit modules,system architecture,layout,and testing.The final test results show that the current shunt monitor chip meets related design requirements.