A single-inductor bipolar-output converter with 5 mV positive voltage ripple for active matrix OLED

Abstract

This paper proposed a single inductor bipolar outputs (SIBO) switching converter for the active matrix Organic Light-Emitting Diode (AMOLED). The negative voltage is generated by the inverting buck-boost converter, which is regulated by the high signal-to-noise ratio comparator. Moreover, the boost converter is utilized to provide the positive output voltage. The proposed switching converter uses the switch sequential to reduce the positive voltage ripple to about 5 mV with the proportional-integral (PI) compensator to guarantee good line and load-regulation. Simulation results show the positive output voltage is regulated to 5 V and the negative output voltage is -7 V for driving the AMOLED. When the load current is 25 mA and the ESR is 30 mΩ, the output voltage ripples are equal to 5 mV and 11 mV for positive and negative voltages, respectively. Besides, the load and line regulations of positive output voltage are 0.24 mV/mA and 5 mV/V, respectively. The maximum efficiency is 88.5% when the input voltage is 4.5 V and the load current is 50 mA.