Fast Threshold Voltage Compensation AMOLED Pixel Circuit Using Secondary Gate Effect of Dual Gate a-IGZO TFTs

We report a fast threshold voltage (VTH) compensation pixel circuit for active-matrix organic light-emitting diode displays. The circuit utilizes the secondary gate effect in amorphous-indium-gallium-zinc-oxide thin-film transistors (TFTs) with the dual-gate (DG) (bottom and top gate) structure and consists of three single-gate TFTs, one DG driving TFT, and two capacitors. It compensates the initial VTH variation after fabrication and takes into account the carrier mobility differences between the top and bottom channels of a DG TFT by using a correction TFT that enables VTH sampling via the channel with the higher mobility, the bottom channel. This achieves very short VTH sampling time, below 10 μs. Experimental results are consistent with those from Silvaco SmartSpice simulations.