System and methods for extraction of threshold and mobility parameters in AMOLED displays

A data extraction system for an organic light emitting device (OLED) based display, the system comprising:

• a pixel circuit including an organic light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input to provide a programming signal, and a storage device to store the programming signal;
• a charge-pump amplifier having a current input and a voltage output, the charge-pump amplifier including an operational amplifier in negative feedback configuration, wherein the feedback is provided by a capacitor connected between the output and the inverting input of the operational amplifier, a common-mode voltage source to drive the non-inverting input of the operational amplifier, and an electronic switch coupled across the capacitor to reset the capacitor;
• a switch module including the input coupled to the output of the pixel circuit and an output coupled to the input of the charge-pump amplifier, the switch module including a plurality of electronic switches to steer current in and out of the pixel circuit, provide a discharge path between the pixel circuit and the charge-pump amplifier, and isolate the charge-pump amplifier from the pixel circuit;
• and
• a controller coupled to the pixel circuit, charge-pump amplifier and the switch module, the controller controlling input signals to the pixel circuit, charge-pump amplifier and switch module in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including providing a program voltage to the programming input to either:
• pre-charge an internal capacitance of the pixel circuit to a charge level and transfer the charge to the charge-pump amplifier via the switch module to generate the output voltage value;
• or
• provide a current from the pixel circuit to the charge-pump amplifier via the switch module to produce the output voltage value by integration over a certain period of time.