近年來,可攜式移動裝置的需求日益增高,相關居家型人體醫療量測儀器普及化,加上大眾對於可攜式產品日漸依賴,使得可攜式產品對於功能性及規格的要求日漸受重視,然而對於考量現在可攜式產品的發展,趨勢於高效率、低成本。 現今類比數位轉換器(Analog-to-Digital-Converter;ADC)已廣泛的用於系統中。功率消耗是主要的需求,所以低功率耗成為一個熱門話題。本篇論文主要設計降壓轉換器(Buck Converter)控制系統架構,其控制電路的架構主要採用離散時間二階三角積分調變器(Sigma-Delta Modulator;SDM),利用同步整流的方式,減少功率損耗並降低電路的複雜度,提升整體效能。 三角積分調變器藉由超取樣(Over Sampling)與雜訊移頻(Noise Shaping)之機制,可有效降低轉換器輸出的雜訊準位,簡化後的開關電容架構,來提升效率與降低系統功耗。本論文所研製之轉換器具有好的雜訊抑制能力及高轉換效率。模擬結果顯示,雜訊準位低於-75dB,在2.8V的輸出,負載電流250mA可提供最大效率可達到95%。
In recent years, with the rapid development and innovation of the portable products become increasingly rigorous are not only the development of portable products, but also the popularization of home-used human body bio-sensing equipment and the dependence of human. Nevertheless, for the portable products, each design relies on the consideration of the product development always tending to high-efficiency and low-cost standard. Analog-to-Digital Converters (ADCs) play an important role as the band with analog and digital circuit. Power consumption as one of the significant factors is requested lower and lower, so lower power has become a hot topic. This thesis presents the design and research of buck converter whose control circuit architecture uses discrete-time second-order one-bit Delta-Sigma modulator. The architecture is base on the concept of current mode operation, which using synchronous rectification to reduce the power loss and improve the total efficiency. Over-sampling and Delta-Sigma modulation techniques have advantages in low bandwidth and high resolution, and it can effectively reduce the noise level of the converter output. By using simplified switched-capacitor integrator architecture, the proposed circuit achieves high efficiency and low-power. The simulated results show the noise level less than -75dB and efficiency which output voltage is 2.8V achieves 95% with a load current up to 250mA.