Research And Design Of AOT Control Buck Converter Based On On-chip Ripple Compensation

With the advent of wireless Internet of Things(IoT)applications such as wireless sensor networks and consumer electronic products(such as wearable devices),how to prolong the standby time of devices has become a big challenge.At the same time,wireless sensor networks,surveillance and security systems also require the power management chip has a fast load transient response.This requires new power architecture.In view of the above problems,considering that the ripple-based control mode has a fast load transient response,a new Buck converter is proposed in this thesis.The converter combines the COT control and V2 control topology,including a high gain ECP(Error Correction Path)with compensation network and an error amplifier,as well as a high-speed FFP(Feed-Forward Path)with the RC ripple compensation network,which improves the output precision of the voltage while ensuring a fast load response of the system.Besides,the system adopts AOT(Adaptive On Time)control strategy to keep the system's switching frequency constant under different input conditions,reduce the influence of EMI(Electromagnetic Interference).It could automatically convert the frequency to light load mode,effectively improve the system full load efficiency.At the same time,in order to reduce the power consumption,extend battery life,each module of the chip is designed with low power consumption.For the issue of system stability that brought by the commonly used external low ESR ceramic capacitors,the method of using RC filter network to achieve on-chip ripple compensation is put forward to solve the problem that sub-harmonic oscillation occurs when the duty cycle is greater than 50%,and the circuit structure is simple and easy to design.The application circuit of the designed Buck converter is simple.In this thesis,Cadence/Specter is used to design and simulate the system and its sub-modules under the Global Foundry 0.18?m CMOS technology.The results show that the system has good stability under low ESR conditions.In the input voltage range of 2.5?5.5V,the output voltage is constant 1.8V.The switching frequency is 1MHz.It has good output accuracy and fast transient response.The static current of control loop is as low as 1.14?A.The maximum output current is 600mA.In the 10-600mA load range,its efficiency is up to 92.03%.