Pixel level suppression of dark current in gate modulation input ROIC for IRFPAs

A modified gate modulation input (GMI) readout circuit has been proposed for pixel level suppression of dark current. We propose using a current memory circuit connected in parallel with the standard GMI stage. The GMI stage is kept unconnected initially and the current flowing through the detector...

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Bibliographic Details
Published in:Microsystem technologies : sensors, actuators, systems integration actuators, systems integration, 2024-02, Vol.30 (2), p.177-183
Main Authors: Dangi, Manik, Saxena, Raghvendra Sahai, Niranjan, Vandana
Format: Article
Language:English
Subjects:
Dark current
Efficiency
Electronics and Microelectronics
Energy dissipation
Engineering
Equivalent circuits
Instrumentation
Linearity
Mechanical Engineering
Modulation
Nanotechnology
Photodiodes
Pixels
Sensors
Simulation
Technical Paper
Transistors
Unit cell
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Summary:A modified gate modulation input (GMI) readout circuit has been proposed for pixel level suppression of dark current. We propose using a current memory circuit connected in parallel with the standard GMI stage. The GMI stage is kept unconnected initially and the current flowing through the detector gets injected into the memory circuit. Due to the memory effect, the same current keeps flowing there even when the GMI stage is connected. Thus, only the variations in the current pass in to the GMI stage and get integrated on the integration capacitor. This allows suppression of dark current, resulting in the improvement of dynamic range, linearity and maximum integration time, leading to lower noise and improved image performance. To demonstrate these improvements, we have simulated a unit cell in PSPICE using 180 nm CMOS technology models, connected with the equivalent circuit model of an HgCdTe photodiode. The proposed circuit has been found to work well with suppression of dark current, 99.9% linearity and one order of magnitude less noise compared to standard GMI cell at the cost of a little increase in power dissipation. The proposed technique is generic and equally suitable for other types of ROIC unit cell and other photo detectors as well.
ISSN:0946-7076
1432-1858
DOI:10.1007/s00542-023-05584-w