JFET LBCAST (Nikon)

JFET LBCAST (Nikon)

The LBCAST (Lateral Buried Charge Accumulator and Sensing Transistor array) developed by Nikon realises a new concept in image sensors. Compared to conventional CCD or CMOS image sensors, it delivers faster image signal read, better sensitivity and colour reproduction, and lower power consumption.

Nikon's JFET LBCAST sensor appears to be similar to CMOS in the way its electrical charge is transferred to the image processing engine. It is capable of outputting data at a far higher speed however, because the signal is read through two signal lines which are differentiated by colour. The Green signals are output through one line, and all Red and Blue signals are output through another. The reason for dedicating a single channel to green is because human eyes are most sensitive to green, making the green signal the most important for setting contrast and sharpness. (this is also why the RGB colour filter ratio is usually 1:2:1)

The JFET used in the LBCAST sensor (Junction Field Effect Transistor, the amplifier for each pixel who raises the voltage of the signal to be sent through), has a simpler structure than the one used on CMOS sensors, with only three transistors for improved efficiency and fewer layers for better optical matching with the photographic lens.

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