A Low Transient Overshoot Voltage Single Inductor Bipolar Output for AMOLED Applications

This paper presents a novel adaptive constant on-time control mode for the single inductor bipolar output (SIBO) converter for active-matrix organic light-emitting diode (AMOLED) displays to improve the load transient response. The proposed SIBO converter generates bipolar output with only a two-phase operation without additional phase adjustment. The adaptive current structure (ACC) eliminates the mismatch between positive and negative outputs and ensures the converter to operate stably under the control of ACOT. The proposed converter is implemented using HHGBCD 0.18µm CMOS process. The simulation results show that SIBO can provide stable 4.6V positive output and -6V negative output at 1.25MHz operating frequency, and the maximum output current is 300mA. In the ACOT control mode, when the output current varies between 50mA and 300mA, the overshoot voltage is 42mV and the undershoot voltage is 48mV, which effectively reduces the transient overshoot voltage of SIBO.