Research And Design Of An Aot-based Buck Converte With High Accuracy And On-chip Ramp Compensation

With the increasing perfermance of the modern electronic system, power supply’s perfermance is facing more stringent demand. Because of its high efficiency, safety and flexibility, switching converter technology has been widely applied as the power of the communication, automobile, and industry equipment, etc. High accuracy, fast transient, higher integration level and excellent electromagnetic compatibility are the future targets of high performance switching converter. The control strategy applied into the converter mainly decides its performance, so it’s necessary to optimize the traditional control method in order to realize switching converter with higher performance. Recently, COT-control Buck DC-DC converter has been used widely by its simplicity and fast transient, but its ripple-based feature results in some drawbacks, such as output voltage DC offset, dependency on output capacitance ESR and operation frequency variation. In order to solve the above problems, this article researches on the advanced control strategy for high performance switching converter with high accuracy, fast transient, high stability with low ESR and excellent electromagnetic compatibility(EMC).Based on the existing control theories, this article proposes an AOT-based Enhanced-V2 Control Buck Convertor with Remote Differential Sensing. By applying the remote differential sensing function, the accuracy of the remote load point voltage is been improved effectively. By on-chip ramp compensation technology, the Enhanced-V2 control optimizes the accuracy and solves the pulse bursting phenomenon caused by the low ESR of the output capacitance at the same time. The operation frequency setting by one external resistence is approximately constant by adopting the adaptive constant on-time modulation so that the system achieves better EMC. Furthermore, a transient enhanced circuit is designed for boosting the system’s transient recovery speed.Firstly, this article introduces the research trends and the basic theories of the DC-DC converter briefly, then analyses the critical factor influencing the converter’s performance and corresponding solutions in detail. And the derivation result of the system’s control model is accomplished. The system is implemented based on 0.6um CD process by Cadence and verified by Hspice. The simulation results show that the proposed system achieved the expected performance such as high accuracy, fast transient, high stability with low ESR and excellent EMC.