Stable current source for system integration to display substrate

A method of sourcing or sinking current to provide a bias current for programming pixels of a light-emitting display, comprising:

• initiating a calibration operation of a current source or sink circuit by activating a calibration control line to cause a reference current to be supplied to the current source or sink circuit;
• during the calibration operation, storing the current supplied by the reference current in one or more storage devices in the current source or sink circuit;
• deactivating the calibration control line while activating an access control line to cause sinking or sourcing of an output current corresponding to the current stored in the one or more storage devices;
• and
• applying the output current to a column of pixels in an active matrix area of the light-emitting display.

A high output impedance current source or sink circuit for a light-emitting display, the circuit comprising:

• an input that receives a fixed reference current and provides the reference current to a node in the current source or sink circuit during a calibration operation of the current source or sink circuit;
• a first transistor and a second transistor series-connected to the node such that the reference current adjusts the voltage at the node to allow the reference current to pass through the series-connected transistors during the calibration operation;
• one or more storage devices connected to a common reference potential and to one or the other or both of the first and the second transistors;
• and
• an output transistor connected to the node to source or sink an output current from current stored in the one or more storage devices to drive an active matrix display with a bias current corresponding to the output current.