4 research outputs found
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High Dynamic Range Pinned Photodiode Pixel with Floating Gate Readout and Dual Gain
This paper presents a pixel based on the pinned photodiode (PPD) with high dynamic range achieved via in-pixel dual conversion gain. The pixel operates with a single exposure and a single charge transfer out of the PPD. The signal charge is first converted to voltage non-destructively with low gain using capacitive coupling to a floating gate. A second conversion with high gain follows at a pn junction-based sense node after another charge transfer. An increased dynamic range is achieved due to the sensing of the same charge with two different conversion gains. The results from a prototype 10 μm pitch pixel, manufactured in a 180 nm CMOS image sensor process, demonstrate conversion gain ratio of 3:1, dynamic range of 93.5 dB, 2.4 e⁻ RMS readout noise, and negligible image lag. The pixel can operate in global shutter mode with the same low noise as in rolling shutter due to the intermediate signal storage under the floating gate
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Pinned Photodiode Imaging Pixel With Floating Gate Readout and Dual Gain
We present an imaging pixel featuring dual conversion gain in a single exposure based on the pinned photodiode (PPD). The signal charge is first converted to voltage nondestructively using a floating gate, and a second conversion is done at a p-n junction-based sense node (SN). Higher signal dynamic range (DR) is achieved due to the sensing of the same charge with two different conversion gains. The results from a prototype 10- μ m-pitch pixel manufactured in a 180-nm CMOS image sensor process demonstrate a gain ratio of 3, DR of 90 dB, 3.6 e − rms readout noise, and negligible image lag
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
To respond to the high demand for high dynamic range imaging suitable for moving objects with few 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 3 μm pixel is capable of having three conversion gains. Introducing a new split-pinned photodiode structure, linear full well reaches 40 ke−. Readout noise under the highest pixel gain condition is 1 e− 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 16-bit linear signal at 60 fps, and an intra-scene dynamic range of higher than 90 dB was successfully demonstrated. This SEHDR approach inherently mitigates the artifacts from moving objects or time-varying light sources that can appear in the multiple exposure high dynamic range (MEHDR) approach