A Gate-Controlled Lateral Thyristor-Based Pixel With Low-Light-Level Extension for High Dynamic Range Applications

Abstract

A pixel configuration based on a gate-controlled lateral thyristor (GC-LT) is proposed to achieve low-light-level extension with a high dynamic range (HDR). Our previous work has demonstrated that the GC-LT has a high sensitivity in low-light-level conditions, and the trigger time is sensitive to the optical power ranging from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 10^{-{9}}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5\times 10^{-{6}}$ </tex-math></inline-formula> W/cm2. In this article, a sampling circuit and a slope following method are implemented to obtain the light-sensitive trigger time. A multiple short-period slopes method is proposed to compensate for the leakage current effects in long exposure time. By elaborately designing the operating scheme, the GC-LT can also be shifted as a conventional photodiode. Also, the GC-LT-based pixel can be operated in thyristor, linear, and logarithmic modes to extend the dynamic range. Simulation is performed to validate the newly proposed device and pixel circuit. The results show that by combining the three modes, the dynamic range of the pixel is higher than 160 dB, and the minimum detectable signal is as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 10^{-{9}}$ </tex-math></inline-formula> W/cm2.