A Hybrid Single-Inductor Bipolar Triple-Output DC–DC Converter With High-Quality Positive Outputs for AMOLED Displays

Abstract

This paper presents a hybrid single-inductor bipolar triple-output (SIBTO) DC-DC converter for active-matrix organic light-emitting diode (AMOLED) displays. Generating the bipolar rails V OP and V ON for the pixel array and the analog rail AV DD for the source driver with a single inductor greatly reduces the system size and cost. This work adopts the floating negative output topology for an ultra-clean positive output. In addition, we propose a push-pull charge balancer to compensate and regulate the V OP , improving the line and load regulation with continuous currents and acceptable power consumption. This work also proposed a slow-comparator based ordered power distributive control (SC-OPDC) to regulate the AV DD with a pulse-skipping scheme to reduce the power loss. The designed power transistor buffers with adaptive deadtime control improve power conversion efficiency and decrease the required minimum load current of AV DD . The proposed SIBTO converter, implemented in 0.18-µm BCD process, operates at 1.67 MHz. It achieves a peak efficiency of 94.1% at 0.88 W output and a maximum output power of 3.67 W with an efficiency of 87%. The maximum output voltage ripples are 5 mV, 17 mV, and 7.5 mV for V OP , V ON , and AV DD , respectively.