A constant current OLED array driver with an auto-clamped precharge circuit

摘要

A constant current organic LED driver with an auto-clamped precharge circuit includes a reference bias generator 12 and a plurality of column driver cells 11, each being connected to the reference bias generator to form a respective current mirror. Each cell 11 has a PMOS switch transistor MPS, a PMOS current source transistor MPO, and an NMOS precharge transistor MNST. When the driver is turned on, the precharge transistor MNST provides an additional large current to rapidly precharge the OLED. The precharge transistor MNST turns itself off as the voltage on the output node rises. The precharge transistor may be replaced by a diode stack (figure 4). No precharge control signal is required.