A CMOS TDI image sensor for Earth observation

Abstract

Time Delay and Integration (TDI) is used to increase the Signal to Noise Ratio (SNR) in image sensors when imaging fast moving objects. One important TDI application is in Earth observation from space. In order to operate in the space radiation environment, the effect that radiation damage has on the performance of the image sensors must be understood.This work looks at prototype TDI sensor pixel designs, produced by e2v technologies. The sensor is a CCDlike charge transfer device, allowing in-pixel charge summation, produced on a CMOS process. The use of a CMOS process allows potential advantages such as lower power consumption, smaller pixels, higher line rate and extra on-chip functionality which can simplify system design. CMOS also allows a dedicated output amplifier per column allowing fewer charge transfers and helping to facilitate higher line rates than CCDs.In this work the effect on the pixels of radiation damage from high energy protons, at doses relevant to a low Earth orbit mission, is presented. This includes the resulting changes in Charge Transfer inefficiency (CTI) and dark signal.

Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors

“…CMOS Image Sensors (CIS) [1][2][3], also called Active Pixel Sensors (APS), have become the main detector technology for optical imaging systems [1][2][3][4][5][6] in consumer and high-end scientific applications [4][5][6]. These optical sensors are exposed to harsh radiation environments in a wide variety of imaging applications (medical imaging [4][5][6][7], space remote sensing [8,9], nuclear power plant monitoring, inertial confinement fusion plasma diagnostics [10,11]). These radiation environments contain particles (e.g.…”

“…Because state-of-the-art CIS are becoming the main technology for future optical imaging applications in space [8,9,26,27] or nuclear environments [10,28,29], it is important to develop tools for the prediction of the radiation-induced dark current in CIS. In particular, the number, spatial distribution and dark current amplitude of the highest dark current increases need to be anticipated for various optical imagers and irradiation conditions in order to select an appropriate mitigation strategy.…”

The operational characteristics and potential applications of a low voltage EMCCD in a CMOS process

“…This can lead to an incomplete transfer of charge and poor CTE. The CTE performance of sensors implemented in a CMOS process is still often worse than in modern CCDs [14]. Atlas, a commercial software provided by Silvaco, was utilised to simulate the charge transfer in the EM pixel structures.…”