| Multiple output power management units can decrease the power loss of the electronic system while guaranteeing the performance of the electronic components. Single inductor multiple output (SIMO), one kind of this unit, is an important direction for the development of the multiple output power management unit. Due to the advantage of softness, transparence, high resolution and pigmentation, energy-saving, and green characteristic, organic light-emitting diode (OLED) is regarded as the next generation of the novel plane display technology. OLED needs a positive and a negative power supply. On the base of the characteristics of the SIMO and OLED drive circuit, a SIMO switching converter is proposed, which is applied in the OLED plane.This design owns an input ranging from 2.3 to 5.5V, and the maximum output power is 750 mW, meanwhile, the positive voltage is 4.6V, the maximum of the negative supply can be as low as -6V. The proposed structure has good linear regulation. Furthermore, by changing between different modes, this circuit can keep high efficiency in the wide range of load. Besides, the inside compensation is adopted in order to reduce the peripheral area. Firstly, the types of the SIMO as well as the relevant working mode are discussed, then the idea of the whole system and the topology of the circuit is also analyzed. The loop stability of the whole chip is emphasized, including loop gain, loop compensation, and the methods to improve the characteristics of the system such as efficiency, etc.Secondly, based on the whole function of the chip, sub-modules are designed, in which the circuits I took charge of are particularly discussed, which contain the compensator and error amplifier, adjustable delay circuit, as well as the start-delay module. In the end, in terms of the HSPICE, the functions and the characteristics of the sub-modules are validated under different corners. The function of the whole circuit were simulated and verified by all the sub-circuits combined together, and met the orginal design object well. |
