雙向電流模式電容放大器應用於電源轉換器之晶片整合

Abstract

在手持式電子商品大行其道的趨勢之下，高整合性的電子產品除了可以減少電路板的面積，進而達到小型化、減輕重量、低成本的目標，而同時寄生元件的減少也能夠提升效率、並且避免其對電路特性造成的不良影響，增加精確度。 以電流模式控制的直流-直流功率轉換器能夠在不同的負載情形下提供較為準確的輸出電壓，使負載端電路之工作特性受負載變化的影響最小化。其回授補償方式較簡單但相對地其控制電路也較電壓模式控制複雜，除了外部的一個電壓回授迴路之外，還必須包含內部的一個電流回授迴路，因此晶片整合的難度較高。為了完成電流模式控制直流-直流功率轉換器的晶片整合並且減少外部腳位的數目，必須將電感電流感測、功率電晶體以及控制電路、系統補償電路全部以有限面積的互補式金氧半場效電晶體電路以及被動元件實現。 本論文提出一個嶄新的雙向電流模式電容放大器，針對如何將補償電路之中構成極點、零點的被動元件部分以主動電路的型式取代提出方法，其中包含單端及雙端放大兩種型式的電容倍乘器以分別配合兩種不同形式的直流-直流電源轉換器系統補償電路，根據利用TSMC 0.35 μm mixed signal 2P4M 製程模擬並且實驗的驗證結果，可以知道其響應特性與傳統使用被動元件之直流-直流電源轉換器響應非常近似。

With the increasing the demands of the portable devices, high integration not only reduces the physical area on the printed circuit board, but also reaches the goals of smaller size, lighter weight and lower cost. By the way, the reduction of the parasitic components results in the increment of the efficiency and accuracy of the chip. Current-mode controlled DC-DC converters could provide a more accurate output voltage for a wide loading range because of the easy compensation. Besides, both the line regulation and load regulation of the current-mode controlled DC-DC converters are better than those of the voltage-mode controlled DC-DC converters because of dual loops. However, the complexity of the current-mode controlled DC-DC converter is higher than that of the voltage-mode controlled DC-DC converter. In addition to an outer voltage feedback loop, there exists an inner current feedback loop to construct the current-mode control architecture. Therefore, the design of the current-mode controlled DC-DC converters are more difficult than that of the voltage-mode controlled DC-DC converters. In order to reduce the number of the pins, the current-mode controlled DC-DC converter, including on-chip current-sensing, power MOS transistors, control architectures and compensator, are necessary to integrate on a chip. This thesis proposes a novel architecture of bidirectional current-mode capacitor multiplier for on-chip DC-DC converter compensation. Single-ended and two-ended capacitor multipliers are invented for implementing two types of compensators. Based on TSMC 0.35μm mixed signal 2P4M technology, the simulations and experimental results show that the performance of the DC-DC converter is the same as that of the conventional DC-DC converter.