High-capacity DC-DC converters for active matrix OLED display

摘要

Two DC-DC converters for bipolar outputs is implemented which are suitable for large-size AM-OLED (Active-Matrix Organic Light Emitting Diode) display. The positive output voltage is regulated by a buck DC-DC converter, and the negative one is regulated by a inverting buck-boost DC-DC converter. Both DC-DC converters operate in a current mode in order to enhance the transient responses. The improved discrete-mode detection circuit is proposed to achieve high-efficiency and accurate output voltages when converters operate in discontinuous-conduction mode. Compensation blocks such as artificial ramp and PI-compensator are incorporated for maintaining stability. The DC-DC converters are fabricated in a 0.35-um BCD technology. For typical operating conditions, maximum efficiencies of buck and inverting buck-boost converters are 92% and 83.1%, respectively.