Pseudo-Type-III Compensation Integrated in a Voltage-Mode Buck Regulator

A pseudo-type-III compensation circuit integrated in a 2.25-MHz voltage-mode dc-dc buck regulator is presented. By summing high- and low-frequency signal paths at the outputs of an error amplifier, two zeros are generated to counteract the pair of complex LC poles. Comparing with traditional and various reported type-III compensation, the proposed scheme is compact, and the area of the compensation capacitor is reduced by about 37%. The addition of a high-frequency path also helps to improve the transient response. Experimental results show that the fabricated regulator with the proposed scheme achieves good stability and fast load-step response. The output is settled within 10 μs for a load current step of 400 mA. In addition, the measured load regulation and line regulation is 0.2%/A and 0.2%/V, respectively. The current consumption of the compensator is 120 μA and the measured maximum efficiency is up to 96%.