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This paper presents a capacitor current based adaptive hysteresis controlled DC-DC converter. This controller avoids wide range frequency band filter or complicated compensation. Based on that capacitor current reflects the load current directly and fast, the proposed system uses a simple analog differentiator to sense the voltage capacitor current. Meanwhile, a PI compensation loop is added to improve loop accuracy. The adaptive hysteresis control is implemented by a frequency regulator. The adaptive hysteresis controller ensures the hysteresis comparator work at a fixed frequency. Also, the system is optimized by introducing a ramp generator. The ramp generator is the combination of the PI compensation and the differentiator. This optimization simplifies and minimizes the controller. The system is designed in TSMC 0.35 um standard CMOS process. Simulation results show that when load current changes from 1 A to 10 A (10% to 100% of full load) at 1A/ns, the restore time is 8.93 us.
Date of Conference: 28-31 March 2010