In this paper, we design a DC-DC boost converter with RF noise immunity to supply a stable positive output voltage for OLED displays. For RF noise immunity, an input voltage variation reduction circuit (IVVRC) is adopted to ensure display quality by reducing the undershoot and overshoot of output voltage. The boost converter for a positive voltage Vpos operates in the SPWM-PWM dual mode and has a dead-time controller using a dead-time detector, resulting in increased power efficiency. A chip was fabricated using a 0.18 um BCDMOS process. Measurement results show that power efficiency is 30% ~ 76% for load current range from 1 mA to 100 mA. The boost converter with the IVVRC has an overshoot of 6 mV and undershoot of 4 mV compared to a boost converter without that circuit with 18 mV and 20 mV, respectively.