Random line selected charge accumulation readout structure for random access infrared imager application

A 512 x 512 monolithic platinum silicide focal plane array with random line selection was proposed. The device was modified from an interline transfer charge couple device configuration by adapting a random line selected char ge accumulation structure on a vertical register and four-tap readout struc ture on a horizontal register to achieve a high fill factor, high charge ha ndling capacity, and high frame rate operation. An on-chip 9-bit decoder wa s used to select a particular line to transfer charges to their associated vertical charge coupled device (CCD) register. Accompanied with the vertica l reset drain circuitry, 1-512 lines can be selected and read out by the ve rtical CCD registers. The dummy charges on the unselected lines are then tr ansferred to the vertical CCD channel and dumped to the vertical reset drai n. In this unique readout structure, a frame rate of upto 240 frames/s can be obtained to select 128 x 128 of Schottky barrier detectors for 5 MHz clo ck frequency operation. By changing the selection pattern on a 9-bit decode r, the device can be operated in either interlaced or non-interlaced format , and the charge integration time can be varied which results in variable e xposure control. This architecture not only maintains the advantages of CCD structure for its low noise and excellent signal to noise ratio, but also provides readout capability of any portion of the array like MOS structure does. (C) 2000 Elsevier Science Ltd. All rights reserved.