Wide-Supply-Voltage-Range Buck-Boost Single-Inductor Dual-Output DC-DC Converter with Pulse-Frequency-Modulation Control

An integrated pulse-frequency-modulation controlled buck-boost single-inductor dual-output dc-dc converter with wide supply voltage range is proposed. In addition, the all-comparator feedback control technique is used, which means that error amplifiers are replaced by comparators to monitor the output voltage. By using this technique, the converter can achieve fast transient response, and has no stability problem. Moreover, no external compensation components are needed. In fact, the proposed PFM-controlled converter is suitable for low-power applications, such as powering biomedical sensing chips. The proposed converter chip was fabricated by a 0.35-mu m CMOS process, and its input voltage range may ranges from 1.8 V to 4.2 V. There are two outputs in the proposed converter, 1.8 V and 3.3 V, and their maximal output currents are 120 mA and 90 mA. The load-regulations of these two outputs are 0.0066 %/mA and 0.008 %/mA, and the cross-regulations are 0.001 %/mA and 0.0004 %/mA.