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In this paper, a sub-1 V input single-inductor dual-output (SIDO) DC-DC converter with an adaptive load-tracking control (ALTC) technique is proposed for single-cell-powered portable devices. The ALTC technique adaptively and accurately adjusts storage charge in form of the inductor current according to actual load condition without wasting surplus charge and increasing cross-regulation through the use of minimized the number of switch and optimum current sequence. A current-mode ring oscillator with a self-bias current source (SBCS) circuit is proposed to replace conventional startup oscillator to produce a nearly constant system clock. The test chip was fabricated by TSMC 0.25 mum 2.5 V/5 V BCD process and experimental results show a high efficiency of 92 % and a cross- regulation smaller than 10 mV.