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

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 $V_{\mathrm {OP}}$ and $V_{\mathrm {ON}}$ for the pixel array and the analog rail AVDD 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 $V_{\mathrm {OP}}$ , 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 AVDD 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 AVDD. The proposed SIBTO converter, implemented in 0.18- $\mu \text{m}$ 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 $V_{\mathrm {OP}}$ , $V_{\mathrm {ON}}$ , and AVDD, respectively.