| Integrated circuit has become the material foundation of the modern information society,and occupies an important position in all fields of the national economy and the people's livehood.Especially in recent years,with the development of mobile Internet and information technology,various electronic products are developing rapidly,and the the demand for power management chips is also rapidly increasing.The power management chip is an important part of the circuit system.Its main responsibility is to control,store and distribute energy.In particular,limited to the stagnation of battery materials,the battary capacity has not been greatly improved.The energy consumption of electronic products is higher and higher,which highlights the importance of power management chips.The highest market share in the battary management chip is LDO(Low Dropout Regulator).Compared with other kinds of power management chips,the LDO has many advantages,such as simple structure,small area,easy integration,low noise,low power consumption.It is suitable for electronic production products such as low power radio frequency tags.The typical structure of the LDO circuit consists of an error amplifier,a bandgap reference circuit,a power transistor,and a feedback network and so on.A typical LDO circuit is usually connected to a large capacitance outside the chip to ensure the stability of the circuit system.With the improvement of circuit integration,it is required to remove off chip capacitance.This paper analyzes the characteristics of the loop stability of the LDO circuit and uses Miller's compensation method to ensure the stability of the LDO circuits and to design an integrated circuit.This circuit is ready to apply to RFID electronic tags,so the transient response is also required to be faster.However,in a typical LDO circuit,the gainbandwidth product of the error amplifier is a constant,so the response speed and gain are constradictory.Therefore,in order to improve the response speed,this paper proposes a pushpull circuit structure.In this paper,a push-pull circuit structure is proposed,which can effectively improve the circuit's response speed,and the transient response speed of the simulation circuit is about 100 ns.Besides,this paper also proposes an overshoot protection circuit.When the current on the load increases instantly,the overshoot protection circuit can work quickly and release the excess current,thus protecting the nomal operation of the circuit.The LDO circuit has a stable output voltage of 0.9V and consumes approximately 829 mW.The operational amplifiers of this paper uses a two-stage operational amplifier by comparing and analyzing the common two-stage operational amplifiers,sleeve casecode operational amplifiers and folded cascode operational amplifiers.The first stage of the operational amplifier is a differential pair circuit,and the second stage is a common souce circuit.Through design optimization,the gain of the proposed operational amplifier is 64.7dB,the phase margin is 61.3°,the ideal phase magin is 60°,and the 0dB bandwidth is 25 MHz.Today's electronic products,because of battery limitation,are increasingly demanding for low power consumption.One of the most effctive ways is to reduce power consumption is to reduce the voltage.In this paper,several typical structures of bandgap reference circuit are introduced.Finally,two kinds of bandgap reference circuit with output voltage less 1V are proposed.One is a bandgap reference circuit based on bipolar transistors,and the other is a reference circuit based on CMOS transistor.Finally,through simulation comparison,the temperature coefficient of the reference circuit with the bipolar transistor as the core is 3.7ppm/°C,and the temperature coefficience of the reference circuit with the CMOS transisitor is 11.68ppm/°C,and the output voltage of the former is lower.Therefore,the bipolar transistor-based bandgap reference circuit is used in this paper.Its circuit power consumption is about 62 uW. |
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