| Summary: | 碩士 === 國立交通大學 === 電機工程學系 === 104 === Constant-on-time (COT) control with an additional current feedback path in conventional buck converter has the advantage of using low equivalent series resistance (ESR) output capacitor. Unfortunately, the disadvantage is output voltage regulation accuracy is greatly deteriorated by its DC offset voltage from the current feedback. More seriously, opposite reaction between output voltage and the additional current feedback signal deteriorates transient response. Therefore, in this paper, pseudo wave tracking technique is proposed to reduce load-dependent DC offset voltage for improving load regulation. Furthermore, this technique improves the instantly opposite reaction between output voltage and inductor current. In addition, this technique extends on-time and the off-time periods in case of light-to-heavy and heavy-to-light load change, respectively. Test chip fabricated in UMC 28nm CMOS process demonstrated that offset voltage is improved from 42mV to 4mV. Besides, the transient response can be improved to 4μs and 5μs when load changes from 0.3 to 1.7A and vice versa, respectively. The advantages of compact size, low cost, and high performance power management can maintain wearable electronics small volume, light, and sustainable.
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