A Programmable Compact Control Mechanism for Ultra-Low Power Current-Mediated CMOS Imager

A novel ultra-low power control mechanism is presented for Mega-pixels current-mediated CMOS imagers. Within the proposed technique, the operating read-out pixel and reset pixel are located in the same column, controlled by only 2-bit lines/pixel compared with 4-bit in previous reported design. The number of transistors for each pixel is reduced from the standaxd 6 transistors to 4 in the current design. Because the read-out and reset modes axe separated into two phases in series for the proposed mechanism, only one reference current source is used, by which the power consumption can further be saved and also the chip area would be shrunk. Minimum wiring overhead is required in the proposed pixel as two control lines are removed. Furthermore, a programmable electronic shutter is adopted to adjust the integration time. The proposed design is simulated using TSMC 0.18um technology, with more than 80% fill factor for a 17 x 17um(2) pixel dimension.