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This brief proposes employing each of the classical 4 transistor (4T) pinned photodiode (PPD) CMOS image sensor (CIS) pixels, for both imaging and temperature measurement, intended for compensating the CISs' dark current, and dark signal non-uniformity (DSNU). The proposed temperature sensors rely on the thermal behavior of MOSFETs working in subthreshold region, when biased with ratiometric currents sequentially. Without incurring any additional hardware or penalty to the CIS, they are measured to have thermal curvature errors less than ±0.3 °C and 3sigma process variations within ±1.3 °C, from 108 sensors on 4 chips, over a temperature range from -20 °C to 80 °C. Each of them consumes 576 nJ/conversion at a conversion rate of 62 samples/s, when quantized by 1 st-order 14 bit delta-sigma ADCs and fabricated using 0.18mu text{m} CIS technology. Experimental results show that they facilitate digital compensation for average dark current and DSNU by 78% and 20%, respectively., Accepted author manuscript, Electronic Instrumentation

A deep subelectron temporal noise CMOS image sensor (CIS) with a Gm-cell based pixel and a correlated-double charge-domain sampling technique has been developed for photon-starved imaging applications. With the proposed technique, the CIS, which is implemented in a standard 0.18-μm CIS process, features pixel-level amplification and achieves an input-referred noise of 0.5 e−rms with a correlated double sampling period of 5μs and a row read-out time of 10 μs. The proposed structurealso realizes a variable conversion gain (CG) with a period-controlled method. This enables the read-out path CG and the noise-equivalent number of electrons to be programmable according to the application without any change in hardware. The experiments show that the measured CG can be tuned from 50 μV/e- to 1.6 mV/e- with a charging period from 100 ns to 4μs. The measured characteristics of the prototype CIS are in a good agreement with expectations, demonstrating the effectiveness of the proposed techniques., Accepted Author Manuscript, Electronic Instrumentation

In this work, a novel approach is presented for measuring relative temperature variations inside the pixel array of a CMOS image sensor itself. This approach can give important information when compensation for dark (current) fixed pattern noise (FPN) is needed. The test image sensor consists of pixels and temperature sensors pixels (=Tixels). The size of the Tixels is 11 μm × 11 μm. Pixels and Tixels are placed next to each other in the active imaging array and use the same readout circuits. The design and the first measurements of the combined image-temperature sensor are presented., Electronic Instrumentation

In a 4T pixel, the transfer gate (TG) “OFF” surface potential is one of the important parameters, which determines the pinned photodiode (PPD) full well capacity. The feed-forward effect measurement is a powerful tool to characterize the relationship of the PPD injection potential and the feed-forward electrons. In this paper, a parameter Vb is introduced to characterize the TG “OFF” surface potential and Vb can be extracted from the feed-forward measurement result. Using this characterization method, the pixel design and application parameters will be investigated. To better understand and control the full well capacity of the PPD, these effects and parameters will be investigated in this paper. Two test chips, using different technologies, were implemented. Further, the different mechanisms of the feedforward effect will be discussed., Microelectronics, Electrical Engineering, Mathematics and Computer Science

Microelectronics, Electrical Engineering, Mathematics and Computer Science

In a 4T pixel, the transfer gate (TG) “OFF” surface potential is one of the important parameters, which determines the pinned photodiode (PPD) full well capacity. The feed-forward effect measurement is a powerful tool to characterize the relationship of the PPD injection potential and the feed-forward electrons. In this paper, a parameter Vb is introduced to characterize the TG “OFF” surface potential and Vb can be extracted from the feed-forward measurement result. Using this characterization method, the pixel design and application parameters will be investigated. To better understand and control the full well capacity of the PPD, these effects and parameters will be investigated in this paper. Two test chips, using different technologies, were implemented. Further, the different mechanisms of the feedforward effect will be discussed., Microelectronics, Electrical Engineering, Mathematics and Computer Science

A micro-digital sun sensor (?DSS) is a sun detector which senses a satellite’s instant attitude angle with respect to the sun. The core of this sensor is a system-on-chip imaging chip which is referred to as APS+. The APS+ integrates a CMOS active pixel sensor (APS) array of 368×368??pixels , a 12-bit analog-to-digital converter, and digital signal processing circuits. The ?DSS is designed particularly for microsatellite applications, thus low power consumption is the major design consideration. The APS+ reduces power consumption mainly with profiling and windowing methods which are facilitated by the specific active-pixel design. A prototype of the APS+ which is designed in a standard 0.18-?m CMOS process is presented. The APS+ consumes 21 mW at 10 fps, which is 10 times less than the state of the art. In order to improve noise performance, a reset noise reduction method, quadruple sampling (QS), is implemented. QS reduces the effect of the reset noise compared to the conventional delta double sampling method, even in a 3-transistor active pixel structure. The APS+ obtains an accuracy of 0.01 deg with the QS method., Microelectronics, Electrical Engineering, Mathematics and Computer Science

A micro-digital sun sensor (?DSS) is a sun detector which senses a satellite’s instant attitude angle with respect to the sun. The core of this sensor is a system-on-chip imaging chip which is referred to as APS+. The APS+ integrates a CMOS active pixel sensor (APS) array of 368×368??pixels , a 12-bit analog-to-digital converter, and digital signal processing circuits. The ?DSS is designed particularly for microsatellite applications, thus low power consumption is the major design consideration. The APS+ reduces power consumption mainly with profiling and windowing methods which are facilitated by the specific active-pixel design. A prototype of the APS+ which is designed in a standard 0.18-?m CMOS process is presented. The APS+ consumes 21 mW at 10 fps, which is 10 times less than the state of the art. In order to improve noise performance, a reset noise reduction method, quadruple sampling (QS), is implemented. QS reduces the effect of the reset noise compared to the conventional delta double sampling method, even in a 3-transistor active pixel structure. The APS+ obtains an accuracy of 0.01 deg with the QS method., Microelectronics, Electrical Engineering, Mathematics and Computer Science

Micro-Digital Sun Sensor (?DSS) is a sun detector which senses the respective angle between a satellite and the sun. It is composed of a solar cell power supply, a RF communication block and a CMOS Image Sensor (CIS) chip, which is called APS+. The paper describes the implementation of a prototype of the ?DSS APS+ processed in a standard 0.18?m CMOS process. The ?DSS is applied for micro or nano satellites. Power consumption is a very rigid specification in this kind of application, thus the APS+ is optimized for low power consumption. This character is realized by a specific pixel design which implements profiling and windowing during the detection process. The profiling is completely fast and power efficiently by a “Winner Take ALL (WTA)” principle. The measurement results shows that the APS+ achieves a reduction of power consumption by more than a factor 10 compared to state of-the-art. Besides the low power consumption, the APS+ also proposes a quadruple sampling method which improves thermal noise with 3-T Active Pixel image Sensor (APS) structure., Microelectronics, Electrical Engineering, Mathematics and Computer Science

This paper presents a low noise CMOS image sensor (CIS) using 10/12 bit configurable column-parallel single slope ADCs (SS-ADCs) and digital correlated multiple sampling (CMS). The sensor used is a conventional 4T active pixel with a pinned-photodiode as photon detector. The test sensor was fabricated in a 0.18 colonm CMOS image sensor process from TSMC. The ADC nonlinearity measurement result shows totally 0.58% nonlinearity. Using the proposed column-parallel SS-ADC with digital CMS technique, 65% random noise reduction is obtained. The significant noise reduction enhances the sensor's SNR with 9 dB., Microelectronics, Electrical Engineering, Mathematics and Computer Science

We analyze the “ageing” effect on image sensors introduced by neutrons present in natural (terrestrial) cosmic environment. The results obtained at sea level are corroborated for the first time with accelerated neutron beam tests and for various image sensor operation conditions. The results reveal many fascinating effects that these rays introduce on image sensors., Microelectronics, Electrical Engineering, Mathematics and Computer Science

Micro-Digital Sun Sensor (?DSS) is a sun detector which senses the respective angle between a satellite and the sun. It is composed of a solar cell power supply, a RF communication block and a CMOS Image Sensor (CIS) chip, which is called APS+. The paper describes the implementation of a prototype of the ?DSS APS+ processed in a standard 0.18?m CMOS process. The ?DSS is applied for micro or nano satellites. Power consumption is a very rigid specification in this kind of application, thus the APS+ is optimized for low power consumption. This character is realized by a specific pixel design which implements profiling and windowing during the detection process. The profiling is completely fast and power efficiently by a “Winner Take ALL (WTA)” principle. The measurement results shows that the APS+ achieves a reduction of power consumption by more than a factor 10 compared to state of-the-art. Besides the low power consumption, the APS+ also proposes a quadruple sampling method which improves thermal noise with 3-T Active Pixel image Sensor (APS) structure., Microelectronics, Electrical Engineering, Mathematics and Computer Science

This paper presents a low noise CMOS image sensor (CIS) using 10/12 bit configurable column-parallel single slope ADCs (SS-ADCs) and digital correlated multiple sampling (CMS). The sensor used is a conventional 4T active pixel with a pinned-photodiode as photon detector. The test sensor was fabricated in a 0.18 colonm CMOS image sensor process from TSMC. The ADC nonlinearity measurement result shows totally 0.58% nonlinearity. Using the proposed column-parallel SS-ADC with digital CMS technique, 65% random noise reduction is obtained. The significant noise reduction enhances the sensor's SNR with 9 dB., Microelectronics, Electrical Engineering, Mathematics and Computer Science

We analyze the “ageing” effect on image sensors introduced by neutrons present in natural (terrestrial) cosmic environment. The results obtained at sea level are corroborated for the first time with accelerated neutron beam tests and for various image sensor operation conditions. The results reveal many fascinating effects that these rays introduce on image sensors., Microelectronics, Electrical Engineering, Mathematics and Computer Science

This paper presents a CMOS imager sensor with pinned-photodiode 4T active pixels which use in-pixel buried-channel source followers (SFs) and optimized row selectors. The test sensor has been fabricated in a 0.18-mum CMOS process. The sensor characterization was carried out successfully, and the results show that, compared with a regular imager with the standard nMOS transistor surface-mode SF, the new pixel structure reduces dark random noise by 50% and improves the output swing by almost 100% without any conflicts to the signal readout operation of the pixels. Furthermore, the new pixel structure is able to drastically minimize in-pixel random-telegraph-signal noise., Electronic Instrumentation Laboratory, Electrical Engineering, Mathematics and Computer Science

Charge Coupled Devices (CCDs) optically coupled to scintillation crystals can be used to construct high resolution gamma cameras. Previously, several groups have reported intrinsic detector spatial resolutions below 100 microns. When the CCD images can be read out fast enough, the energy and interaction position of individual gamma quanta can be estimated by a real-time image analysis of the scintillation light flashes. The Electron-Multiplying CCD (EMCCD) is well-suited for fast read out, since even at high frame rates it has extremely low readout noise. However, due to the often very low light levels present in scintillation gamma cameras, further reduction of noise is desirable. Here, the EMCCD is optically coupled to a 1000- µ-thick columnar CsI(Tl) crystal for Tc-99m and I-125 imaging.We investigate noise reduction through summing of signals in pixels before the gain register and readout circuit of the EMCCD (“pixel binning”). We compare the energy and spatial resolution, photopeak efficiency (PE) and signal-to-noise ratio (SNR) of an EMCCD-based gamma camera for the case of binning vs. non-binning. When pixels were read out simultaneously in groups of 4 the spatial resolution is slightly worse in the direction of binning, but the number of false-positive counts resulting from background noise for I-125 was reduced by 74% compared to the no binning case. We conclude that the use of charge binning when reading out EMCCDs may significantly improve the energy spectra and noise properties of CCD-based high-resolution gamma cameras., Radiation, Radionuclides and Reactors, Applied Sciences

This paper presents a CMOS imager sensor with pinned-photodiode 4T active pixels which use in-pixel buried-channel source followers (SFs) and optimized row selectors. The test sensor has been fabricated in a 0.18-mum CMOS process. The sensor characterization was carried out successfully, and the results show that, compared with a regular imager with the standard nMOS transistor surface-mode SF, the new pixel structure reduces dark random noise by 50% and improves the output swing by almost 100% without any conflicts to the signal readout operation of the pixels. Furthermore, the new pixel structure is able to drastically minimize in-pixel random-telegraph-signal noise., Electronic Instrumentation Laboratory, Electrical Engineering, Mathematics and Computer Science

Charge Coupled Devices (CCDs) optically coupled to scintillation crystals can be used to construct high resolution gamma cameras. Previously, several groups have reported intrinsic detector spatial resolutions below 100 microns. When the CCD images can be read out fast enough, the energy and interaction position of individual gamma quanta can be estimated by a real-time image analysis of the scintillation light flashes. The Electron-Multiplying CCD (EMCCD) is well-suited for fast read out, since even at high frame rates it has extremely low readout noise. However, due to the often very low light levels present in scintillation gamma cameras, further reduction of noise is desirable. Here, the EMCCD is optically coupled to a 1000- µ-thick columnar CsI(Tl) crystal for Tc-99m and I-125 imaging.We investigate noise reduction through summing of signals in pixels before the gain register and readout circuit of the EMCCD (“pixel binning”). We compare the energy and spatial resolution, photopeak efficiency (PE) and signal-to-noise ratio (SNR) of an EMCCD-based gamma camera for the case of binning vs. non-binning. When pixels were read out simultaneously in groups of 4 the spatial resolution is slightly worse in the direction of binning, but the number of false-positive counts resulting from background noise for I-125 was reduced by 74% compared to the no binning case. We conclude that the use of charge binning when reading out EMCCDs may significantly improve the energy spectra and noise properties of CCD-based high-resolution gamma cameras., Radiation, Radionuclides and Reactors, Applied Sciences