Patent ID: 7675562

Claim:
An image sensor, comprising: a plurality of row lines; a plurality of column lines crossing the plurality of row lines; a plurality of pixels, each of the pixels formed at a respective crossing of one of the plurality of row lines with one of the plurality of column lines, each of the pixels generating a charge based on light incident thereon and selectively transferring the charge to the respective column line in response to a single signal without receiving additional control signals, the single signal being received from the respective row line, and each of the pixels including only a photoelectric transformation element and a switching element; and a plurality of column driver circuits, each column driver circuit associated with one of the column lines and configured to generate an output voltage based on the charge on the associated column line, each of the plurality of column driver circuits including, a driver circuit including a drive transistor having a first electrode, a second electrode and a gate, the first electrode being connected to a supply voltage, the second electrode connected to a start circuit, and the gate controlling operation of the drive transistor based on the charge on the associated column line; the start circuit including a start transistor connected between the drive transistor and an active load, with an output of the start transistor to the active load serving as an output of the column driver circuit; and the active load including a load transistor connected between the start transistor and ground, wherein the drive transistor, the load transistor and the start transistor are enhancement mode transistors, and the start transistor is larger in size than the drive transistor and the load transistor.