本論文實現漣波回授導通時間控制之降壓轉換器並操作於固定頻率。漣波回授方面結合電流與電壓回授，有別於傳統電流回授是對於電感電流的感測，本研究採用低通濾波器產生偽電感電流訊號，使其具相同相位之交流訊號與較不受負載電流影響之直流訊號，根據上述回授訊號可以有效降低輸出電容之等效串連電阻且降低穩態誤差。控制方面採取適性式導通時間控制，藉由可調整的導通時間以因應受電路寄生參數影響之頻率變異，使電路之系統頻率定頻。此外使用暫態加速機制改善加入電流回授後造成較慢的暫態響應。
本研究利用PCB佈局建立功率級電路與其回授電路，並以FPGA實現數位導通時間控制法，完成實際電路功能驗證。在數位控制方面亦透過CIC晶片下線進一步驗證其功能。功率級電路輸入與輸出電壓分別為4.2V及1.2V，使用具較低等效串連電阻之積層陶瓷電容實現較小的輸出電壓漣波，在穩態時仍可在不同負載狀況下使系統頻率維持定頻，並於負載變化時，使暫態時間從12μs 減少至6μs。

This thesis presents the ripple-based on-time control on the Buck converter for constant frequency operation. The proposed ripple-based control contains current and voltage loops. Different from the traditional current loop which detects the inductor current, the low pass filter is implemented for reflecting the pseudo inductor current, whose AC signal is in phase with the switching signal and the DC signal is not vulnerable to the variation of load current. With the proposed control loops, there is no need to use the output capacitor with high equivalent series resistance and the steady state error of the output voltage can be effectively reduced. The adaptive on-time control is also introduced to restrain the frequency variation caused by the load current with parasitic elements inside the Buck converter. Besides, the transient boosting mechanism is used to improve the slower transient response that is caused by the introduction of the current feedback loop.
In real implementation, the power stage and the peripheral circuits were built on PCB. The proposed digital constant frequency on time control was validated by both FPGA and tape-out circuit by TSMC 0.18μm manufacturing process. The input and output voltages of the power stage were 4.2V and 1.2V, respectively. The experimental result showed that the operating frequency was fixed at 1MHz in the steady state for the use of MLCC capacitor under various loading conditions. The settling time of transient response was reduced from 12μs to 6μs.

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