Highly Integrated 2-Ch DC-DC Converter with Wide-Input Voltage Range for Wearable AMOLED Display

In this paper, we propose a highly integrated 2-ch DC-DC converter with a wide-input voltage range for wearable AMOLED displays, which generates a normal output voltage even if the over-input voltage is applied. The proposed DC-DC converter generates a positive voltage V_POS and a negative voltage V_NEG for wearable AMOLED displays. The positive voltage V_POS is generated in a boost converter with an over-charged voltage permissible circuit (OPC) which operates in SPWM-PWM dual mode with power transistor width scaling (PTWS) to increase power efficiency. The boost converter has an OPC which generates a stable output voltage even if an over-charged battery input voltage of up to 5.6V is applied. A negative voltage V_NEG is designed using a 0.5 x regulated inverting charge pump to decrease chip size and increase power efficiency. The proposed circuit was designed using a 0.18-μm BCDMOS process. Simulation results show that the proposed DC-DC converter generates V_POS voltages of 4.6V and V_NEG voltage of-0.6 V to -2.3 V for input voltage of 2.9 V to 5.6 V. In addition, it has a maximum power efficiency of 89% and output voltage ripple less than 20 mV for load current range of 1 mA to 70 mA.