A Power-Efficient Hybrid Single-Inductor Bipolar-Output DC-DC Converter with Floating Negative Output for AMOLED Displays

Abstract

This paper presents a hybrid single-inductor bipolar-output (SIBO) DC-DC converter for active-matrix organic light-emitting diode (AMOLED) displays which are relatively more sensitive to the supply noises on their positive supply. This design significantly improves the display quality by achieving a near-zero voltage ripple at the positive output thanks to the negative output floating and the use of low-power shunt regulators. In addition, with the hybrid topology and the proposed cross-coupled bootstrap-based level-shifter with a dual-PMOS inverter buffer, low-voltage devices without deep-N-well are used, reducing the chip area and cost. The proposed converter is implemented in a 0.35-µm CMOS process with 5-V devices. The targeted output voltages are 5.3V and -4.7V. Operating at 1MHz, the measured positive output ripple is lower than 1mV in all the conditions. The measured peak power efficiency is 89.3% at 1.1W output power. The maximum output power is 3.5W.