• Journal of Sensor Science and Technology
• /
• v.14 no.4
• /
• pp.272-277
• /
• 2005

A CMOS active pixel sensor has been designed and fabricated using standard 2-poly and 4-metal $0.35{\mu}m$ CMOS processing technology. The CMOS active pixel sensor has been made up of a unit pixel having a highly sensitive PMOSFET photo-detector and electronic shutters that can control the light exposure time to the PMOSFET photo-detector, correlated-double sampling (CDS) circuits, and an 8-bit two-step flash analog to digital converter (ADC) for digital output. This sensor can obtain a stable photo signal in a wide range of light intensity. It can be realized with a special function of an electronic shutter which controls the light exposure-time in the pixel. Moreover, this sensor had obtained the digital output using an embedded ADC for the system integration. The designed and fabricated image sensor has been implemented as a $128{\times}128$ pixel array. The area of the unit pixel is $7.60{\mu}m{\times}7.85{\mu}m$ and its fill factor is about 35 %.

• Journal of Sensor Science and Technology
• /
• v.27 no.3
• /
• pp.160-164
• /
• 2018

In this paper, a wide dynamic range complementary metal-oxide-semiconductor (CMOS) image sensor with the adjustable sensitivity by using cascode metal-oxide-semiconductor field-effect transistor (MOSFET) and inverter is proposed. The characteristics of the CMOS image sensor were analyzed through experimental results. The proposed active pixel sensor consists of eight transistors operated under various light intensity conditions. The cascode MOSFET is operated as the constant current source. The current generated from the cascode MOSFET varies with the light intensity. The proposed CMOS image sensor has wide dynamic range under the high illumination owing to logarithmic response to the light intensity. In the proposed active pixel sensor, a CMOS inverter is added. The role of the CMOS inverter is to determine either the conventional mode or the wide dynamic range mode. The cascode MOSFET let the current flow the current if the CMOS inverter is turned on. The number of pixels is $140(H){\times}180(V)$ and the CMOS image sensor architecture is composed of a pixel array, multiplexer (MUX), shift registers, and biasing circuits. The sensor was fabricated using $0.35{\mu}m$ 2-poly 4-metal CMOS standard process.

• Journal of Sensor Science and Technology
• /
• v.20 no.1
• /
• pp.14-18
• /
• 2011

An analytical pinning-voltage model of a pinned photodiode has been proposed and derived. The pinning-voltage is calculated using doping profiles based on shallow- and exponential-junction approximations. Therefore, the derived pinning-voltage model is analytically expressed in terms of the process parameters of the implantation. Good agreement between the proposed model and simulated results has been obtained. Consequently, the proposed model can be used to predict the pinning-voltage and related performance of a pinned photodiode in a CMOS active pixel sensor.

• Journal of Sensor Science and Technology
• /
• v.23 no.2
• /
• pp.87-93
• /
• 2014

In this paper, we propose a block-based low-power complementary metal oxide semiconductor (CMOS) image sensor (CIS) with a simple pixel structure for power efficiency. This method, which uses an additional computation circuit, makes it possible to reduce the power consumption of the pixel array. In addition, the computation circuit for a block-based CIS is very flexible for various types of pixel structures. The proposed CIS was designed and fabricated using a standard CMOS 0.18 ${\mu}m$ process, and the performance of the fabricated chip was evaluated. From a resultant image, the proposed block-based CIS can calculate a differing contrast in the block and control the operating voltage of the unit blocks. Finally, we confirmed that the power consumption in the proposed CIS with a simple pixel structure can be reduced.

• Journal of Sensor Science and Technology
• /
• v.27 no.6
• /
• pp.357-361
• /
• 2018

This paper presents an averaging current adjustment technique for reducing the pixel resistance variation in a bolometer-type uncooled infrared image sensor. Each unit pixel was composed of an active pixel, a reference pixel for the averaging current adjustment technique, and a calibration circuit. The reference pixel was integrated with a polysilicon resistor using a standard complementary metal-oxide-semiconductor (CMOS) process, and the active pixel was applied from outside of the chip. The averaging current adjustment technique was designed by using the reference pixel. The entire circuit was implemented on a chip that was composed of a reference pixel array for the averaging current adjustment technique, a calibration circuit, and readout circuits. The proposed reference pixel array for the averaging current adjustment technique, calibration circuit, and readout circuit were designed and fabricated by a $0.35-{\mu}m$ standard CMOS process.

• Broadcasting and Media Magazine
• /
• v.5 no.1
• /
• pp.59-71
• /
• 2000

This paper presents a survey of the CMOs-based image sensor and its applications to various real field digital camera. CMOS image sensor, called active pixel sensor (APS), has many interesting properties such ash I회 sensitivity, high speed readout, random access and lower power consumption when it is compared with CCd. this paper also addresses the state-of-the-art of CMOS image sensor, and gives some examples of its application to digital camera and special-purpose cameras. with the advancement of semiconductor technology, CMOS image sensor is a future technology for imaging system, and will be widely used in the filed of image capturing for consumer electronics and scientific measurements.

• Journal of Sensor Science and Technology
• /
• v.12 no.4
• /
• pp.149-155
• /
• 2003

A PMOSFET photodetector for highly-sensitive active pixel sensor(APS) is presented. This sensor uses 5V power supply and has been designed and fabricated using I-poly and 2-metal $1.5{\mu}m$ CMOS technology. The feature of a PMOSFET photodetector is that the polysilicon gate of the PMOSFET was connected to n-well, in order to increase the photo sensitivity. The designed MOS photodetector has similar $I_{DS}-V_{DS}$ characteristics with a standard MOSFET. One dimensional image sensor with 16 pixels based on the PMOSFET photodetector has also been designed and fabricated. Unit pixel of the designed sensor consists of a PMOSFET photodetector and 4 NMOSFETs. Unit pixel area is $86{\mu}m{\times}90.5{\mu}m$ and its fill factor is about 12%.

• Journal of Sensor Science and Technology
• /
• v.24 no.2
• /
• pp.79-82
• /
• 2015

This paper proposes a novel complementary metal oxide semiconductor (CMOS) active pixel sensor (APS) and presents its performance characteristics. The proposed APS exhibits a linear-logarithmic response, which is simulated using a standard $0.35-{\mu}m$ CMOS process. To maintain high sensitivity and improve the dynamic range (DR) of the proposed APS at low and high-intensity light, respectively, two additional nMOSFETs are integrated into the structure of the proposed APS, along with a photogate. The applied photogate voltage reduces the sensitivity of the proposed APS in the linear response regime. Thus, the conversion gain of the proposed APS changes from high to low owing to the addition of the capacitance of the photogate to that of the sensing node. Under high-intensity light, the integrated MOSFETs serve as voltage-light dependent active loads and are responsible for logarithmic compression. The DR of the proposed APS can be improved on the basis of the logarithmic response. Furthermore, the reference voltages enable the tuning of the sensitivity of the photodetector, as well as the DR of the APS.

• Journal of Sensor Science and Technology
• /
• v.17 no.2
• /
• pp.114-119
• /
• 2008

Wide dynamic range active pixel sensor(APS) using a charge pump circuit has been designed by using 2-poly 4-metal $0.35{\mu}M$ standard CMOS technology. The structure of the proposed APS is similar to the structure of the conventional 3-Tr APS. The proposed unit pixel consists of one photodiode and three MOSFETs. Using a charge pump circuit, the dynamic range of the proposed APS is increased, compared to the conventional 3-Tr APS.

• Journal of Sensor Science and Technology
• /
• v.18 no.6
• /
• pp.475-484
• /
• 2009

In this paper, an analysis of the complementary CMOS active pixel and readout circuit is carried out. Complementary pixel structure which is different from conventional 3TR APS structure consists of photo diode, reset PMOS, several NMOSs and PMOSs sets for complementary signals. Proposed CMOS image sensors pixel has been fabricated using 0.5 standard CMOS process. Measured results show that the output signal range is from 0.8 V to 3.8 V. This output signal range increased 125 % compared to conventional 3TR pixel in the condition of 5 V power supply.