0.293-mm2 Fast Transient Response Hysteretic Quasi-<inline-formula> <tex-math notation="LaTeX">$V^{2}$ </tex-math> </inline-formula> DC–DC Converter With Area-Efficient Time-Domain-Based Controller in 0.35-<inline-formula> <tex-math notation="LaTeX">$\mu$ </tex-math> </inline-formula>m CMOS

Abstract

A time-domain-control-based quasi- $V^{2}$ buck converter with small area, fast transient response, wide load current range, and constant switching frequency is proposed in this paper. The proposed time-domain-based controller achieves compact core area and simplified constant switching frequency control by replacing the conventional voltage-domain comparator with a phase detector having an adaptive detection window. Moreover, a coupling-based inductor current emulator is also proposed to support the discontinuous conduction mode operation in the light load. The proposed buck converter is implemented using 0.35- $\mu \text{m}$ CMOS process. The core area of the proposed buck converter is only 0.293 mm2. The measured peak efficiency in the continuous conduction mode is 92% and the end-to-end efficiency in the load current range of 25–700 mA is 73%. The undershoot/overshoot and recovery time with the up/down load current steps of 510 mA are 38/20 mV and 2.5/2.6 $\mu \text{s}$ , respectively.