Design And Research Of One-cycle-controlled Feedforward Buck DC-DC Convertor

As the market of portable applications developing constantly, the demand on high efficiency, high reliability and fast transient response becomes the new design challenge to switching power supply IC.Based on the knowledge of the operation theory and control mode of the Buck converters, the close-loop control methods are studied deeply, then a new one-cyle feedforward control method are given, and the working principles and performance are explained, then the Buck convertor using this new control method is given. Firstly, the whole architecture of the Buck convertor is put, and the working principles and working process are discussed. Secondly, the design procedure of some subblocks are presented, and validated by HSPICE simulation.Finally, the fuction of whole chip is simulated by HSPICE, the results of the simulation are dicussed followly.As bad rejection to load perturbation is the most drawback of traditional One-cycle control, then a new nonlinear control method without this disadvantage called One-cycle Feedforward control is proposed. The new strategy sampling both of the output voltage and the input source voltage of the convertor, and put them two into integral and control the pulse width of the control signal. Using the control method, with better rejection to power source, the Buck convertor has better rejection to load perturbation also.The simulations for this design are implemented based on the 0.6μm BCD process. The results indicate that the converter has a fast transient response, a good line regulation, a good load regulation and a good soft start performance.