A 10-[Formula Omitted] Transient Recovery Time Low-EMI DC-DC Buck Converter With [Formula Omitted]-[Formula Omitted] Modulator

This paper presents a 10-[Formula Omitted] transient recovery time and a low electromagnetic interference dc-dc buck converter with a second-order delt-sigma ([Formula Omitted]-[Formula Omitted] modulator. The proposed buck converter employs the techniques of oversampling, noise shaping, fast-transient path, mode selector, and second-order [Formula Omitted]-[Formula Omitted] modulator to achieve spur reduction and to improve transient recovery time. As a result, the noise tones of the output voltage are less than the other conventional pulsewidth modulation converters. In addition, the fast-transient path could correct output voltage immediately, and the mode selector controls the duty cycle of the converter to limit overshoot voltage and undershoot voltage. The chip was implemented using a 0.35-[Formula Omitted] Taiwan Semiconductor Manufacturing Company CMOS process. The measured results show that the transient recovery time is 10 [Formula Omitted] from heavy load to light load and from light load to heavy load, and the noise power spectrum demonstrates a -64-dBm peak noise when the output voltage is 2 V and the output current is 300 mA. A maximum efficiency of 89% is measured at 3 V output voltage and at 3.6 V supply voltage.