Patent ID: 8502751

Claim:
A pixel drive circuit for use in a display, the pixel drive circuit comprising: switching circuitry for providing a reference current input; a current mirror for providing a drive current to a light emitting device based on the reference current, the current mirror including: a drive thin film transistor for conveying the drive current through the light emitting device, the drive thin film transistor being connected in series with the light emitting device; a reference thin film transistor for receiving the reference current, the reference thin film transistor having a gate connected to a gate of the drive transistor, the reference thin film transistor having a reference node coupled to a biasing potential for balancing the current mirror, wherein a first node of the drive thin film transistor corresponding to the reference node is not connected to the biasing potential, thereby preventing a mismatch between the reference thin film transistor and the drive thin film transistor over time; and a capacitor for storing a program voltage independent of a transistor threshold voltage, the program voltage settling on the capacitor while the reference current is conveyed through the reference thin film transistor, the capacitor having a terminal coupled to both the gate of the drive thin film transistor and the gate of the reference thin film transistor.