A Single-Inductor Multiple-Output Buck/Boost DC–DC Converter With Duty-Cycle and Control-Current Predictor

Abstract

A single-inductor multiple-output (SIMO) buck/boost dc-dc converter with average-current control is presented in this article. With the proposed duty-cycle and control-current predictor, fast and robust reference tracking of inductor current is achieved. The conventional charge-balance method is modified together with an auto-tuning-divider-based duty generator to release the cross-regulation to the last channel. Moreover, an anti-right-half-plane zero method is also proposed to suppress cross-regulation during large loading transient when the SIMO dc-dc converter operating in the boost mode. The proposed SIMO buck/boost dc-dc converter has four output channels which are adaptive to both boost and buck operations and is implemented in a standard 0.35-μm CMOS process. Measurement results show that the proposed dc-dc converter achieves a peak efficiency of more than 89% at a total output power of about 0.5 W, load transient's response time of less than 40 μs, cross-regulation within 0.05 V/A when a 300-mA loading transient is applied to a boost channel.