电子设备的高速发展对电源管理芯片设计提出了更高的要求，而基于电感器的降压型直流变换器 (BUCK) 作为电源管理芯片的重要组成部分有着极为广泛的用途。近年来，由于高频 BUCK 体积小、响应快等特点顺应时代潮流，因此高频BUCK 的研究热度持续上升，尤其是电压模式高频 BUCK，因为输出电压纹波小而备受青睐。高频高性能电压模式 BUCK 的设计难点在于，如何在确保其可靠性的前提下提升其输出电压范围。这是因为传统电压模式 BUCK 所采用的电压到占空比（Voltage-to-duty-cycle, V2D）转换器中含有比较器，虽然比较器延时的影响在低频时可以忽略，但是在高频时将变得显著。该延时不仅会使高频 BUCK 的频率偏低，还会压缩高频 BUCK 的输出电压范围。本文研究的重点在于设计一款适用于高频 BUCK 的 V2D 转换器，使其能够扩大高频 BUCK 的输出电压范围，令 BUCK 在动态电压缩放的场合中有更广泛的应用。为了实现新型无比较器的线性 V2D 转换器的设计，本文详细分析了现有 V2D转换器技术的优劣，并对 V2D 转换器进行了创新： 1) 不再改变输入比较器的参考电压，而是改变输入比较器的斜坡电压的初值来实现 V2D 的转换，一方面使比较器能够被反相器所取代，令输出占空比范围不再受到比较器延时的限制，由此提升了 BUCK 的输出电压范围，另一方面使转换器的传输函数能够保持线性，从而降低频率补偿的难度； 2) 利用运放负反馈及采样技术设计电流校准电路，自适应地产生偏置电压来控制电流源的充放电电流，确保斜坡电压幅值和斜率固定，从而使转换器免受工艺、电压和温度的影响； 3) 对一款甲乙类 (class-AB) 电压缓冲器的结构加以改进，通过为其添加互补的镜像结构提高了其摆率，并降低了其功耗，确保 BUCK 有较快的瞬态响应及较高的功率效率。以 V2D 转换器为核心，本文采用 180nm CMOS 工艺设计了一款高频高性能电压模式 BUCK，目前已完成了流片。后仿结果显示，该 BUCK 在输入电压为 3.3V、开关频率为 10M～40MHz 的频率范围内，都可以正常工作。其中，在 30HMz 的开关频率下， BUCK 的输出电压范围相比前沿设计至少提升 9%，输出电压纹波约2.7mV，瞬态响应的恢复时间约 1.5?s，最大负载电流达到 1A，峰值效率达到 92%。
The rapid development of electronic devices has put forward higher requirements for the design of power management chips, and inductor based BUCK DC converters, as an important component of power management chips, have extremely wide applications. In recent years, due to its small size and fast response, high-frequency BUCK is in line with the trend of the times. And the research heat of high requency BUCKs has continued to rise, especially voltage mode high frequency BUCKs, which are favored due to their small output voltage ripple. The design diffculty of high frequency and high performance voltage mode BUCK lies in how to improve its output voltage range while ensuring its reliability. This is because the voltage-to-duty-cycle (V2D) converter used in traditional voltage mode BUCK contains comparators. Although the effect of comparator delay can be ignored at low frequencies, it will become significant at high frequencies. This delay not only causes the frequency of the high frequency BUCK to be low, but also compresses the output voltage range of the high frequency BUCK.The focus of this thesis is to design a linear V2D converter without comparators suitable for high frequency BUCK to expand the output voltage range of high frequency BUCK and make the BUCK have a wider application in dynamic voltage scaling. In order to achieve the design of a new type of linear V2D converter without comparators, this thesis analyzes in detail the advantages and disadvantages of existing V2D converter technologies, and innovates V2D converter: 1) no longer changing the reference voltage input to the comparator, but changing the initial value of the ramp voltage input to the comparator to achieve V2D conversion. On the one hand, by enabling the comparator to be replaced by an inverter, the output duty cycle range is no longer limited by the comparator delay, thereby the output voltage range of BUCK improves. On the other hand, the transmission function of the converter can remain linear, so the diffculty of frequency compensation is reduced. 2) Designing a current calibration circuit using the negative feedback and sampling techniques to adaptively generate bias voltage to control the charging and discharging current of the current source, ensuring that the amplitude and slope of the ramp voltage are fixed, thereby protecting the converter from the influence of process, voltage, and temperature. 3)Improving the structure of a class AB voltage buffer by adding complementary mirror structures to increase its slew rate and reduce its powerconsumption, ensuring fast transient response and high power effciency of the BUCK.Based on the V2D converter, a high frequency and high performance voltage mode BUCK has been designed using the 180nm CMOS process in this paper. And the design has been fabricated. The post-layout simulation results show that the BUCK can operate normally within the frequency range of 10M～40MHz with 3.3V input voltage. At a switching frequency of 30MHz, the output voltage range of BUCK is improved by at least 9% compared to the cutting-edge design, the output voltage ripple is about 2.7mV, the transient response recovery time is about 1.5 ?s, the maximum load current reaches 1A, and the peak effciency reaches 92%.
