A fast-transient-response buck converter with Split-Type III compensation and charge-pump circuit technique

In order to achieve fast transient response and high efficiency on a CMOS DC-DC buck converter, Split-Type III (ST3) compensation technique and a charge-pump circuit would be proposed and presented in this paper. The proposed buck converter has been fabricated with a TSMC 0.35-μm CMOS 2P4M process. This compensation design tries to add a charge pump circuit into the compensator for improving its transient response time. The operating frequency of the proposed buck converter is 1MHz for input voltage 3.3V and output voltage range 1.0V-2.5V applications. The proposed structure using charge pump circuit technique can achieve fast transient response when load current changes between light load and heavy load, and vice versa. Compared with conventional Type III compensator, ST3 can reduce unnecessary area and power consumption of passive components. Measured result shows that the settling time of the converter output is less than 2 μs for a load current step of 200 mA. Peak power efficiency of 90.8% is obtained at 100 mA load current. The whole chip area is 1.49 mm×1.46 mm(include PADs).