A TDI imager synchronizes linear motion of the scene with multiple samplings of the same object to obtain an increased signal-to-noise ratio. The image sensor is based on IMEC's proprietary embedded charge-coupled device (CCD) technology and it was developed by IMEC for the French Space Agency, CNES, which plans to utilize the technology for space-based earth observation.
The sensor combines a light sensitive CCD-based TDI pixel array with CMOS readout electronics.The CCD pixel structure delivers low-noise TDI performance in the charge domain, while CMOS technology enables low-power, on-chip integration of fast and complex circuitry readouts. The CMOS technology enables on-chip readout electronics, such as clock drivers and analog-to-digital convertors (ADCs), operating at higher speeds and lower power consumption not possible with traditional CCD technology.
The prototypes were fabricated using a 130nm CMOS manufacturing process with an additional CCD process module at IMEC's 200-mm wafer fab. A charge transfer efficiency of 99.9987 percent has been measured ensuring almost lossless transport of charges in the TDI array, and guaranteeing high image quality.
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