The fundamental nature of image systems favors a large sensor array in order to collect more light, resulting in image reproductions that captures a high level of detail. However, in image applications today, the physical size of the camera module is tightly constrained requiring small pixel sensors. For example, in order to use 1/4” optics for slim profile camera phones, a 2.2µm pixel size is required for 2 Megapixel resolution and a 1.75µm pixel size is required for 3 Megapixel resolution. At these pixel sizes and resolutions, the sensor must be able to balance several design elements to obtain the highest sensitivity and dynamic range.   

The challenges of small pixel applications have led to innovations in CMOS image sensor design that continue push the boundary of image quality performance. The adoption of 4-transistor (4T) pixel design have significantly improved dark current and reset noise performance. However, to maintain the highest level of sensitivity, care must be taken to minimize noise and parasitic capacitance from the photodiode and read out circuit. For small pixels, read noise is one of the key limiting factors for low-light sensitivity requiring low noise designs (for large pixels the limiting factor is photon shot noise) . The entire pixel readout process is also performed at a high rate in order to minimize the artifacts and motion blur of the image. This is especially important for higher speed video quality. If all of these design elements are done right, minimal digital compensation is required, resulting in accurate reproduction that is true-to-life.

To meet the challenges of small pixel design,  Himax Imaging is developing a series of sensor products based on a new generation of proprietary designs. With proven experience in designing CMOS image sensors and SoC solutions for high volume imaging applications, Himax Imaging utilizes the latest technology in CIS process, optics modeling, mixed-signal design and image processing to deliver the right size, power, cost and convenience required for high resolution sensors in extremely small form factor.  Himax Imaging sensors are highly integrated to minimize system cost and space for a wide variety of applications.