Charged-based compensation and parameter extraction in AMOLED displays

A method of extracting a circuit parameter from a pixel circuit and providing in-pixel compensation for variation or aging of the pixel circuit, the pixel circuit including a light emitting device, a drive transistor to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal, the method comprising the steps of:

• causing an in-pixel compensation of the pixel circuit by
• applying a reference voltage from a first line to a storage device in the pixel circuit and
• redirecting to a second line current from a first node between the drive transistor and the light emitting device
• to charge the storage device based on the reference voltage to self-compensate for a variation or aging of the drive transistor or the light emitting device or both in the pixel circuit;
• extracting, using a circuit external to the pixel circuit, the circuit parameter from the pixel circuit;
• and
• subsequently driving the pixel circuit using programming information that has been compensated based on at least the extracted circuit parameter.