A Simultaneous Energy Transferring SIBO Converter Achieving Low Ripple and High Efficiency for AMOLED Applications

This article presents a single-inductor bipolar-output (SIBO) converter for active-matrix organic light-emitting diode (AMOLED) displays to reduce output ripples and enhance power conversion efficiency (PCE). We propose the simultaneous energy transferring SIBO (SETSIBO) converter, which generates bipolar outputs with only a two-phase operation and does not require additional switching. The hybrid power stage with a flying capacitor and two-phase operation reduces the dc value of the inductor current, which mitigates conduction losses and output ripples; moreover, the hybrid power stage allows the high-voltage switches in the conventional converters to be replaced by low-voltage switches. The inductor current reduction and the low-voltage power switch use improve the PCE. This article analyzes the proposed converter’s output ripple reduction and the PCE improvements; furthermore, the load imbalance is effectively compensated with the proposed SETSIBO converter. The prototype of the proposed SETSIBO is fabricated in a 0.5-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process. The measured ripples at positive and negative outputs are 24.5 and 28 mV, respectively, with a 300 mA load current <inline-formula> <tex-math notation="LaTeX">$I_{\mathrm {o}}$ </tex-math></inline-formula>. The measured peak PCE is 94.1%, and the active area is 1.46 mm2.