An Over 90 dB Intra-Scene Single-Exposure Dynamic Range CMOS Image Sensor Using a 3.0 μm Triple-Gain Pixel Fabricated in a Standard BSI Process
Sensors 2018, 18(1), 203
To respond high demand on high dynamic range imaging suitable for moving objects with less artifacts, we have developed a single-exposure dynamic range image sensor by introducing a triple gain pixel and a low noise dual gain readout circuit. The developed 3m pixel is capable of having three conversion gains. Introducing a new split pinned photodiode structure, linear full well reaches 40ke-. Readout noise under the highest pixel gain condition is 1e- with a low noise readout circuit. Merging two signals, one with high pixel gain and high analog gain and the other with low pixel gain and low analog gain, a single exposure dynamic rage (SEHDR) signal is obtained. Using this technology, a 1/2.7”, 2M-pixel CMOS image sensor has been developed and characterized. The image sensor also employs an on-chip linearization function, yielding a 16bit linear signal at 60fps, and intra-scene dynamic range of higher than 90dB was successfully demonstrated. This SEHDR approach is inherently free from artifacts from moving objects or the time varying light sources, which could appear in the multiple exposure high dynamic range (MEHDR) approach.