NEW LOW-NOISE OUTPUT AMPLIFIER FOR HIGH-DEFINITION CCD IMAGE SENSOR

A new low-noise CCD output amplifier, the "RJG detector," has been developed. The RJG detector incorporates a JFET which has an electrically floating ring-junction gate (RJG). The operating principle of the amplifier is that signal charges, transferred from the CCD into the RJG, directly modulate the drain current in the detection JFET. Performance of the detector was evaluated by operating test devices under 37-MHz clock frequency, which is the same frequency as that for the horizontal CCD operation in the recently developed 2 million pixel high-definition CCD image sensor. It was found that 1/f noise was reduced by introducing the JFET, and that reset noise was completely eliminated by achieving complete charge transfer through the reset operation. As a result, input referred noise equivalent electrons within the 18.5-MHz baseband were reduced to 17 (electrons). The RJG detector is confirmed to be suitable for a high-definition CCD image sensor.