本論文分析一項與提出二項直流-直流降壓轉換器的快速負載暫態響應技術，含分析先前最先進的輸出電容電流偵測器校正技術，提出背景式電容電流偵測器校正技術與補償電流源校正技術，共實現三個晶片。
直流-直流降壓轉換器須具備快速負載暫態響應，以對負載供電並滿足效能與能源效率的需求，當大且快的負載電流暫態發生時，轉換器輸出電壓過衝與下衝小且穩定時間短。輸出電容電流可立即反映步階上升/下降的負載電流，並可被用來精確控制功率開關的導通時間與關斷時間，以在一次開關動作即穩定輸出電壓，但輸出電容阻抗受製程、輸出電壓準位、溫度與老化影響，使輸出電容電流偵測器不準確，可能使負載暫態響應變慢。本論文探討先前最先進的輸出電容電流偵測器校正技術：降低切換頻率讓輸出電容與電容電流偵測器的阻抗分別被電感、電容與電阻支配，再校正讓二者的電感性、電容性與電阻性阻抗比例相同，使電容電流偵測器產生的電流與輸出電容電流呈比例；分析校正誤差對負載暫態響應的影響，並歸納此技術適用於前景校正。
本論文提出背景電容電流偵測器校正技術，以事件/週期性致能校正因應短期/長期的輸出電容阻抗變異，根據電容電流偵測器輸出偵測準穩態以觸發校正，若遭遇負載暫態或動態電壓調節可立即中斷校正，並在下次偵測到準穩態時繼續或重新開始校正。此外，不改變切換頻率即可偵測電容電流偵測器與輸出電容的阻抗不匹配並校正，以維持校正時的輸出電壓品質，包含穩態漣波與暫態抖動；量測效能與現有一流文獻的降壓轉換器比較，本成果在校正過程產生的額外輸出電壓穩態漣波與暫態抖動皆可忽略，校正時間較短，在快且大的負載暫態變動時輸出電壓下衝、過衝與穩定時間分別最接近其理論最小值。
為突破標準直流-直流降壓轉換器負載暫態響應速度的先天限制，本論文提出背景校正的暫態輸出電流穩定器，包含與輸出電感並聯的補償電流源及其校正電路，以快速地在負載電流變動時穩定輸出電壓，另包含一個背景校正電路，以確保補償電流在製程、電壓與溫度變異時仍可準確。量測結果顯示，在負載電流暫態變動0.45 A與1 A下，輸出電壓維持在其標稱值的1% 內，下衝與過衝小於18 mV，故穩定時間視為可忽略。與現有一流文獻比較，本成果達到最快負載暫態響應速度，輸出電壓過衝與下衝最小且穩定時間最短。

This dissertation analyzes one and proposes two fast load-transient response techniques for DC-DC buck converters, including an analysis of prior state-of-the-art capacitor-current-sensor (CCS) calibration technique, and proposals of a background CCS calibration technique and a transient output-current regulator (TOCR) with calibration. Three chips are implemented.
DC-DC buck converters featuring fast load-transient response is essential for powering loads to meet their performance and energy-efficiency requirements. Hence, when a large and rapid load-current Iload transient occurs, the converter’s output voltage VO has small undershoot VUS and overshoot VOS as well as short settling time tS. The output-capacitor current ICo can instantly reflect a step-up/down Iload transient, and then be used to precisely control the power-switch on-time and off-time to settle VO in a one on-off switching. However, the output capacitor’s impedance ZCo varies with fabrication process, different VO levels, temperature drifts, and aging, causing an inaccurate CCS thus potential slowdown of load-transient response. This dissertation discusses prior state-of-the-art CCS calibration, which decreases switching frequency to make ZCo and CCS’ impedance ZCs dominated by their respective inductive, capacitive, and resistive parts, calibrates ZCs to ensure the same ratio in the inductive, capacitive, and resistive parts of ZCs/ZCo. Thus, the CCS output current ICs emulates a scaled replica of ICo. This dissertation also analyzes the calibration error effects on load-transient response and concludes the calibration is suitable for foreground operation.
This dissertation proposes a background CCS calibration technique. This calibration is event/periodically enabled for short/long-term ZCo variations, activated when a quasi-steady state (QS) is detected according to ICs, interrupted by a load-transient or dynamic-voltage-scaling event, and reactivated in the next QS. Besides, this calibration identifies mismatches between ZCo and ZCs in steady state with an unaltered switching frequency and then calibrates ZCs, leading to maintained VO quality including steady-state ripples and transient fluctuations during calibration. Compared with other state-of-the-art buck converters, this work achieves less VO steady-state error and transient fluctuations during calibration, less calibration period, and VUS, VOS and tS closer to their respective theoretical minima.
To break the inherent limitation of load-transient response in standard dc-dc buck converters. This dissertation proposes a TOCR with background calibration. The TOCR includes a compensation current source (CompCS) in parallel with the output inductor to rapidly regulate VO during Iload transients, and a calibration circuit to ensure an accurate compensation current under process-voltage-temperature variations. Under 0.45-A and 1-A Iload transients, the measured VO remains within 1% of its nominal 1.8 V, with VUS and VOS both being less than 18 mV and a negligible tS. Compared with other state of the arts, this work achieves the fastest load-transient response with the smallest VUS/VOS and shortest ts.

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