Abstract: High speed serial interface-MDDI (Mobile Display Digital Interface),due to its many advantages such as high transmission speed,low power consumption,high reliability,fewer cables and low EMI (Electro-Magnetic Interference),is widely used in the portable mobile display equipments such as mobile phones.This paper presents a physical layer circuit design of MDDI which is used in AM-OLED (Active Matrix-Organic Light Emitting Diode) driver IC.The circuit is designed in a TSMC 0.35 μm CMOS technology,the circuit supports both the normal operation and low power operation modes.The simulation results show that,the circuit can operate at the rate of 400 Mb/s for per transition line,which is completely satisfied with the MDDI standard,and in the low power operation mode,the static power consumption is only 0.75 mW.