Research And Design On Control Loop Of Buck Converter With Adaptive Compensation

Mobile phones,SoC,motherboards and other electronic devices need high-quality power supply with important specifications of voltage regulation,load regulation and transient recovery time.Nowadays,because the load range of electronic equipments is large,the instability resulted from load changes is likely to lead to the malfunction of the load device or performance deterioration.Therefore,in order to obtain a stable supply voltage very quickly,and it is expected that the power supply has a better load regulation,better voltage regulation and faster transient recovery time.This thesis focuses on the research and design of an adaptive compensated peak current mode Buck converter loop.Based on the analysis of the traditional compensation scheme of the current mode buck converter combined with the difference of the step response of the single pole system and the “single pole” system with a doublet,a voltage loop compensation circuit which can realize the zero tracking compensation and a slope compensation circuit capable of adaptive duty cycle and switching frequency were designed.The new voltage loop compensation circuits make full use of the detected load information to adjust the compensation resistor,which can realize zero movement and a more accurate doublet cancellation.In addition,this thesis uses current-type Miller compensation effect to achieve the capacitance doubling.As a result,the introduction of adaptive compensation circuits make it possible to achieve not only on-chip integrated compensation network but also a better load transient response.This thesis introduces the modulation mode and loop control strategy specifically,especially for the requirements of the current/voltage loop compensation circuit.Then,from the point of view of stability and dynamic performance,the process of load transients is analyzed in detail.The thesis used MATLAB and SIMPLIS to analyze the problems of the settling time and anti-jamming analysis which is important in the the design of the adaptive loop compensation circuits.After that,the loop compensation circuits,oscillator and PWM comparator circuit were introduced.The simulation shows that the designed circuits can realize the improvement of the transient response performance as well as the on-chip integration of the compensation network.