A new unit cell design with automatic input stage selection capability for increased SNR


This paper presents novel unit cell architecture for short wave infrared (SWIR) imaging applications. It has two input stages which are CTIA and SFD covering for both respectively low and high light levels and automatic input stage selection circuitry that chooses best input stage. A user can select 2 modes for FPA manual and automatic mode. In manual mode, user can set CTIA or SFD for all pixels according to user needs. In automatic mode, each pixel selects input stage itself according to light level. Automatic input stage selection for each pixel brings high SNR level and low noise along with highest possible dynamic range. Standard CMOS 0.18µm TSMC technology is used to realize unit cell. In the architecture of unit cell, circuit level techniques are used to optimize layout size.