A compact rail-to-rail buffer with current positive-feedback for LCD source driver

A new compact rail-to-rail buffer amplifier for active matrix liquid crystal display source driver applications is proposed. Two complementary buffer amplifiers driving a pair of column lines are used to realize a rail-to-rail driver. The compact buffer amplifier has a large driving capability with the function of charge and discharge provided by the current positive-feedback (CPF). The CPF can increase the charge capability in conventional class-A pMOS input buffer amplifiers and increases the discharge capability in conventional class-A nMOS input buffer amplifiers. The compact rail-to-rail buffer amplifier is implemented using 0.35 mum CMOS 2-poly 4-metal process technology. The quiescent current consumed is 2.8 muA and 3 muA for a pMOS input buffer amplifier and an nMOS input buffer amplifier, respectively.