Selecting an Analog Front-End for Imaging Applications

INTRODUCTION Every imaging system starts with an image sensor. The signal from the sensor must be processed in the analog domain, converted to digital, and further processed in the digital domain. This allows the image to be analyzed, manipulated, and enhanced, prior to storage, display, transmission, and/or further processing. Imaging applications typically involve three chips—an image sensor, an analog front-end (AFE), and a digital ASIC. The AFE conditions the analog signal received from the image sensor and performs the analog-to-digital (A/D) conversion. The digital ASIC contains image-processing and timing-generation circuitry. Figure 1 shows a block diagram of a typical imaging system. Additional application-specific circuitry following the digital imageprocessing ASIC depends upon whether the imaging system is a camera, scanner or copier.