Research And Design Of DC-DC Converters Based On Time Domain Control Technology

With the promotion and popularization of distributed power systems and the rapid development of battery powered mobile electronic devices,the demand for DC-DC power modules in electronic systems is becoming increasingly strong,and the performance requirements for them are also increasing.In addition to pursuing conventional electrical performance indicators,DC-DC converters are developing towards small size,fast frequency,low power consumption,and high efficiency.This article focuses on the research of buck DCDC converters,consulting a large number of literature and combining with the current development trend of DC-DC converters,a buck DC-DC converter based on time-domain current control method is designed.Through a detailed discussion and analysis of the conduction mode,modulation mode,and control mode of the buck DC-DC converter,this thesis found that there are serious drawbacks and shortcomings in achieving high frequency and efficiency DC-DC converters under existing control modes such as analog voltage control mode,analog current control mode,and digital PWM control mode.Combining the advantages of digital control mode and analog control mode,and following a top-down design philosophy,a buck DC-DC converter system based on time-domain current mode control mode as the core was designed.The use of differential transconductance voltage controlled oscillators and differential transconductance voltage controlled delay lines as core control circuits provides lossless integration and proportional functions,resulting in a smaller ripple in the output voltage of the DC-DC converter.The use of an RS trigger with a cycle skip detector in the PWM generation circuit not only improves the transient response ability of the DC-DC converter,but also greatly increases the switching frequency of the DC-DC converter due to its small delay,playing a crucial role in reducing the output voltage ripple of the DC-DC converter and the size of the chip peripheral components.In response to issues such as increasing the switching frequency and reducing the conversion efficiency of the power supply,the on chip LDO using dynamic bias shunt feedback technology ensures the stability of the LDO and reduces the working voltage of the internal circuit of the DC-DC system,thereby reducing some static losses of the system;The dead time control circuit adopts the technology of dynamically adjusting the dead time to reduce the conduction loss of high-end power transistors and lowend transistors.The system has also designed a comprehensive protection circuit and an on chip soft start circuit to ensure that the chip can work normally at different temperatures and power voltages.The above module circuit construction,system circuit connection,and simulation verification were all completed on the Cadence platform,and the layout was designed and drawn.The DC-DC converter based on time-domain current mode control method introduced in this thesis is designed based on the TSMC 0.18μm process.Through simulation results,it can be concluded that under the conditions of ambient temperature of-40 ℃-125 ℃ and input voltage of 1.8V-2.0V,the output voltage is 1.2V,and the voltage ripple is less than 143.5μV;Load current 240 m A,peak efficiency up to 88.9%;The switching frequency is 8MHz,and the external inductance L and capacitance C are only 220 n H and 20μF,respectively,greatly reducing the area of the chip’s peripheral devices.All the above indicators meet the design requirements.