28奈米製程虛擬波跟蹤技術的固定導通時間 控制型降壓電源轉換器

Abstract

在傳統固定導通時間控制降壓轉換器中附加電流回授路徑具有使用低等效串聯電,的輸出電容的優點，不幸的是，在引入一個額外的電流回授路徑的情況下會產生一個偏移電壓而影響輸出電壓的精確值。更嚴重的是，當負載變化時，輸出電壓和額外的電流回授路徑之間有相反的趨勢，此趨勢會嚴重的劣化固定導通時間控制的暫態響應。因此，在此提出虛擬波跟蹤技術來減少與附載有關的直流偏移電壓量用於改善輸出電壓的精準值，此外這種技術在負載變化時消除了輸出電壓與電感電流之間相反的趨勢來達到快速的暫態響應，並且在負載由輕載到重載和重載到輕載時分別延長了導通時間和非導通時間。本論文中提及的架構實現於二十八奈米製程並驗證了偏移電壓從42毫伏特改善到4毫伏特，除此之外，在負載由0.3安培到1.7安培的抽載範圍內，暫態反應時間也分別縮短至4微秒及5微秒。在本文中所提出的控制方式具有小巧的尺寸、低成本和高效能電源管理適用於穿戴是電子裝置應用中的體積小、輕薄和長使用時間等需求。

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.