Abstract
This paper proposes a CMOS front-end readout-integrated circuit (ROIC) with on-chip non-uniformity compensation technique for a diode-based uncooled infrared image sensor. Two techniques are adopted to achieve on-chip non-uniformity compensation: a reference dummy metal line is introduced to alleviate the dominant non-uniformity with IR-drop presented in large pixel array, and a current splitting architecture-based variable current source for diode bias is proposed to compensate other residual non-uniformity. A differential integrator is chosen as the main amplifier of readout circuit for its superior noise performance. For low power design, a pulse-powered row buffer is designed in this work. The proposed ROIC for 384 × 288 diode-based detector array is fabricated with a 0.35-m CMOS process. It occupies an area of 4.4 mm × 15 mm, and the power consumption is 180 mW. The measured result shows that with the proposed on-chip non-uniformity compensation, the output voltage variation is greatly reduced from 2.5 V to 60 mV.
Highlights
Compared with narrow bandgap photon-based detectors, uncooled thermal-based infrared sensors without cryogenic cooling equipment are getting popular, and expanding their application in many civil fields, because they provide the advantages of lower weight, lower cost and system complexity [1,2,3,4]
We propose a hybrid non-uniformity-compensated readout-integrated circuit (ROIC) for diode-based uncooled infrared sensors
Due to a limited available pad, in testing mode, only 16 row channels are connected to the diode array by bonding wires for rapid evaluation of the ROIC
Summary
Compared with narrow bandgap photon-based detectors, uncooled thermal-based infrared sensors without cryogenic cooling equipment are getting popular, and expanding their application in many civil fields, because they provide the advantages of lower weight, lower cost and system complexity [1,2,3,4]. Lower relative temperature sensitivity means smaller signal voltage, and non-uniformity-induced voltage variation possibly compromises dynamic range or even saturates the readout circuit. In a diode-based sensor, reference pixels and dummy metal line are two classic techniques to calibrate the IR-drop, but other non-uniformity factors are often left un-compensated [17,18]. In a microbolometer, these similar residual non-uniformities are calibrated by applying corrected bias voltage with the help of sub-DAC (Digital-to-Analog Converter) [19,20,21,22].
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