一個具有電流補償路徑的快速暫態反應直流降壓式轉換器

Abstract

本論文闡述一個使用電流補償技術來加速暫態反應的直流電壓轉換器，並利 用台積電0.35μm 2P4M 3.3V/5V Mixed Signal CMOS製程製作晶片。我們另外加上一組補償電流源推挽電流來縮短暫態反應的時間。當負載電流發生暫態變化時，控制器會將控制信號維持在飽和的狀態並且打開其中一個補償電流源來抽出電流或灌入電流藉以加速暫態反應。而在穩定狀態的時候，控制器的控制信號操作在 脈衝寬度調變控制下，並且將補償電流源關閉以維持轉換效率。 根據量測的結果，本晶片的切換頻率操作在1MHz，暫態回復的時間可以降到9 μs，同時暫態漣波電壓減少到130 mV。在負載電流為420 mA時有最高轉換效率為82.21 %。輸入電壓穩定度與負載穩定度分別為0.0184 V/V與0.0633 V/A，而 其他的量測結果與細節包含在本論文內。

In this thesis, a buck converter with current compensation path technique is designed and implemented. The converter utilizes a voltage signal detecting technique such that during transient, the controller saturates the PWM signal and turns on the current compensation path to enhance the load transient response. Detailed analysis was performed and the circuit was implemented with a standard 0.35 μm CMOS process. Measurement results show that the transient response is 9 μs for a minimum to maximum load current step change. The peak converting efficiency of this work is 82.21 %. Therefore, the buck converter is suitable for portable devices. The proposed architecture was successfully implemented as a chip. However, there are some room for improved system performance. The soft start and the over current protection circuits are needed in the converter to ensure safe operation and protect the loading devices from damage. A current sensing circuits is needed to compensate the feedback loop with current mode control method and to better control the current compensation path. Adding these considerations, the buck converter will be much reliable in a practical application.