SOCS058 - JUNE 1996
The Texas Instruments (TITM) TC281 is a frame transfer charge coupled device (CCD) image sensor that provides very high-resolution image acquisition for image-processing applications such as robotic vision, medical X-ray analysis, and metrology. The image format measures 8 mm horizontally by 8 mm vertically; the image area diagonal is 11.3 mm. The image area pixels are 8-um square. The image area contains 1000 active lines with 1000 active pixels per line. Ten additional dark reference lines give a total of 1010 lines in the image area with 36 additional dark reference pixels per line for a total of 1036 pixels per horizontal line.
The storage section of the TC281 contains 1010 lines with 1036 pixels per line. This area is protected from exposure to light by an aluminum light shield. Photoelectric charge that is generated in the image area of the TC281 can be transferred into the storage section in less than 200 us. After image capture (integration time), the readout is accomplished by transferring the charge, one line at a time, into two serial registers located below the storage area, each of which contains 518 pixels and 4 dummy pixels. The typical serial register data rate is 20 megapixels per second for each serial register. If the storage area needs to be cleared of all charge, charge may be quickly transferred across the serial registers and into the clearing drain located below the serial register section.
Gated floating-diffusion detection structures are used with each serial register to convert charge to signal voltage. The outputs are further buffered by low-noise, two-stage, source-follower amplifiers. These two serial registers are combined to give one output at a data rate of 40 megapixels per second. An output of 30 frames per second with one field per frame is typical.
The blooming protection feature of the sensor is based on an advanced lateral-overflow-drain concept. Antiblooming is achieved by providing a dc bias to the overflow-drain bias pin, which provides a typical protection level of 1000:1. It is also possible to clear the image area by providing a single pulse of at least 1 us in duration to the overflow-drain pin.
The TC281 is built using TI-proprietary advanced virtual phase (AVP) technology, which provides devices with high blue response, low dark signal, good uniformity, and single-phase clocking. The TC281 is characterized for operation from -10°C to 45°C.
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