A dual-mode 1.8 V-output DC-DC buck converter with on-chip capacitor multiplier in 0.18 um CMOS

Abstract

This paper presents a dual-mode DC-DC buck converter with on-chip multiplier capacitor-based compensation scheme for portable applications. The proposed converter consists of a power stage and an monolithic CCM/CDM controller that operates with a high clock frequency of 1 MHz. A dual modulation technique is utilized to improve the power conversion efficiency over a wide range of load conditions. In order to reduce chip area the controller, external capacitors are replaced with the on-chip multiplier capacitor-based compensation scheme. Additionally, protection blocks such as over voltage protection (OVP), under voltage lock-out (UVLO) and thermal shutdown (TSD) block are also integrated on the chip. The proposed buck converter was designed and implemented using a 0.18 um CMOS process. The measured results of the fabricated circuit showed a peak efficiency of 94.8%, a ripple voltage of 13.29 mV ripple and an 1.8 V output voltage with a supply voltage ranging from 2.7 to 3.3 V.