Driver circuit for light-emitting device

A driver circuit for a light-emitting device, comprising:

• a light-emitting device controlled by a driving current to emit light;
• a first transistor for transmitting a data signal;
• a second transistor coupled between the light-emitting device and the first transistor, wherein the second transistor is coupled to the first transistor to form a node and generate a divided voltage at the node;
• a third transistor for transmitting the divided voltage;
• a capacitor for storing a capacitor voltage, wherein the capacitor voltage is substantially equal to the divided voltage;
• and
• a fourth transistor coupled to the second transistor and the light-emitting device, wherein the fourth transistor has a threshold voltage, the threshold voltage is equal to a compensating voltage of the second transistor, and the fourth transistor is controlled by the capacitor voltage to generate the driving current;
• wherein, during a data written period, the first transistor, the second transistor and the light emitting device form a loop, the divided voltage in the loop is in proportion to a voltage of the data signal and is substantially equal to the sum of the compensating voltage of the second transistor and the voltage across the light-emitting device, and the divided voltage is adjusted according to a voltage variation in the threshold voltage of the fourth transistor and the voltage across the light-emitting device.