Brookman Technology Inc.

Shizuoka-shi, Japan

Brookman Technology Inc.

Shizuoka-shi, Japan
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Brookman Technology Inc., Ikegami Tsushinki Co. and Japan Atomic Energy Agency | Date: 2017-01-23

A radiation tolerant optical detection element includes: a p-type base-body region; a gate insulating film provided on an upper surface of the base-body region; an n-type buried charge-generation region buried in an upper portion of the base-body region; an n-type charge-readout region buried in an upper portion of the base-body region on the inner-contour side of the buried charge-generation region; an n-type reset-drain region buried on the inner-contour side of the charge-readout region; a transparent electrode provided on the gate insulating film above the buried charge-generation region; and a reset-gate electrode provided on a portion of the gate insulating film between the charge-readout region and the reset-drain region.


Seo M.-W.,University of Shizuoka | Wang T.,University of Shizuoka | Jun S.-W.,Brookman Technology Inc. | Akahori T.,Brookman Technology Inc. | And 2 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2017

In the past several years, CMOS image sensors (CISs) with sub-single-electron noise level, particularly, deep sub-electron read noise (less than 0.5e-rms), have been reported. Such an ultra-low noise level is realized with a reduced floating diffusion (FD) node capacitance for attaining the high pixel conversion gain (CG) [1,2], and a high-gain readout circuitry with noise-reduction capabilities [3,4]. Recently, a reset-gate-less (RGL) CMOS image sensor has been reported [5]. It shows an excellent read noise performance using an optimized pixel structure for high CG and high-gain column ADC with multiple sampling. In this technique, however, a very high pulsed voltage of approximately 25V for the FD reset is essential to cause a punch-through effect. It is not suitable for image sensors with high pixel resolution and high-speed signal readout. © 2017 IEEE.


Watabe T.,NHK Science and Technical Research Laboratories | Kitamura K.,NHK Science and Technical Research Laboratories | Sawamoto T.,University of Shizuoka | Kosugi T.,Brookman Technology Inc. | And 10 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2012

There has been increasing demand for high-reality video systems. Thus, there has been research and development into ultra-high-definition television (UDTV) schemes for the next-generation television broadcasting system called "Super Hi-Vision" (SHV). This system aims to improve viewing experience using higher-resolution pictures. A pixel count of 7680x4320 and frame rate of 120fps are defined as full-spec parameter values for the SHV video signal. The total pixel data output rate of full-spec SHV image sensors will be 48Gb/s or greater. Several image sensors have been developed for UDTV or digital cinema applications [1-4], but they still do not fulfill SHV specifications. © 2012 IEEE.


Seo M.-W.,University of Shizuoka | Sawamoto T.,Brookman Technology Inc. | Akahori T.,Brookman Technology Inc. | Liu Z.,Brookman Technology Inc. | And 8 more authors.
IEEE Transactions on Electron Devices | Year: 2012

A 1.3-megapixel CMOS image sensor (CIS) with digital correlated double sampling and 17-b column-parallel two-stage folding-integration/cyclic analog-to-digital converters (ADCs) is developed. The image sensor has 0.021e rms- vertical fixed pattern noise, 1.2e rms- pixel temporal noise, and 85.0-dB dynamic range using 32 samplings in the folding-integration ADC mode. Despite the large number of samplings (32 times), the prototype image sensor is demonstrated at the video rate operation of 30 Hz by the new architecture of the proposed ADCs and the high-performance peripheral logic (or digital) parts using low-voltage differential signaling circuit. The developed 17-b CIS has no visible quantization noise at very low light level of 0.01 lx because of high grayscale resolution where 1 LSB = 0.1 e-. The implemented CIS using 0.18-mum technology has the sensitivity of 20 V/lx cdot s and the pixel conversion gain of 82 muV/e-. © 2012 IEEE.


Seo M.-W.,University of Shizuoka | Suh S.,University of Shizuoka | Iida T.,Brookman Technology Inc. | Watanabe H.,Sanei Hytechs | And 7 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2011

Low-noise CMOS image sensors (CIS) employing column-parallel amplifiers that significantly reduce temporal noise, as well as electron-multiplication CCD (EM-CCD) image sensors are becoming popular for very-low-light-level imaging. These low-noise imagers with high-gain amplification in either the charge or voltage domains sacrifice the intra-scene dynamic range. Scientific applications of solid-state imagers strongly require very low temporal noise and wide intra-scene dynamic range as well as very high gray-scale resolution. A column-parallel analog-to-digital converter (ADC) and column-level signal processing in CISs are key techniques to meet these requirements. Single-slope [1,2], successive-approximation [3] and cyclic ADCs [4] are widely used for the column-parallel ADC in CMOS imagers. However, these ADCs require additional gain enhancements to achieve very low temporal noise. A recently reported [5] delta-sigma (ΔΣ) ADC has an attractive feature that low temporal noise and high resolution can be simultaneously attained by an oversampling technique. However, for very high resolution, a high number of samplings per pixel output, e.g., more than 360 samplings for 16b, is required. © 2011 IEEE.


Han S.-M.,University of Shizuoka | Takasawa T.,University of Shizuoka | Akahori T.,Brookman Technology Inc. | Yasutomi K.,University of Shizuoka | And 3 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2014

Time-of-Flight (ToF) range imagers have a wide range of applications, such as 3D mice, gesture-based remote controllers, amusement, robots, security systems, and automobiles. Numerous ToF range imager developments have been reported [1-4]. Recent developments are often based on CMOS image sensor technology with pinned photodiode options [5-7], which are suitable for cost-effective mass production. Reported CMOS ToF range imagers use single-tap or two-tap lock-in pixels; to cancel the influence of background light, two or four sub-frames are used to produce a background-canceled range image. These architectures, however, have difficulty with precise range measurements of moving objects, because background light cancelation is not guaranteed for moving objects. Lock-in pixels without any charge-draining gate suffer from background light during the readout time of the operation. Another important issue with CMOS ToF range imagers for high range resolution is the speed of lock-in pixels, which must be improved to use high-modulation-frequency light or short-duration light pulses. © 2014 IEEE.


Seo M.-W.,University of Shizuoka | Suh S.-H.,University of Shizuoka | Iida T.,Brookman Technology Inc. | Takasawa T.,University of Shizuoka | And 6 more authors.
IEEE Journal of Solid-State Circuits | Year: 2012

A low temporal noise and high dynamic range CMOS image sensor is developed. A 1Mpixel CMOS image sensor with column-parallel folding-integration and cyclic ADCs has 80μVrms (1.2e-) temporal noise, 82 dB dynamic range using 64 samplings in the folding-integration ADC mode. Very high variable gray-scale resolution of 13b through 19b is attained by changing the number of samplings of pixel outputs. The implemented CMOS image sensor using a 0.18-μm technology has the sensitivity of 10-V/lx·s, the conversion gain of 67- μV/e-, and linear digital code range of more than 4 decades. © 1966-2012 IEEE.


Seo M.-W.,University of Shizuoka | Sawamoto T.,Brookman Technology Inc. | Akahori T.,Brookman Technology Inc. | Iida T.,Brookman Technology Inc. | And 4 more authors.
IEEE Sensors Journal | Year: 2013

An extremely low temporal noise and wide dynamic range CMOS image sensor is developed using low-noise transistors and high gray-scale resolution (17b) folding-integration/cyclic analog-to-digital converter (ADC). Two types of pixel are designed. One is a high conversion gain (HCG) pixel with removing the coupling capacitance between the transfer gate and the floating diffusion, and the other is a pixel for wide dynamic range (WDR) CMOS imager with a native transistor as a source follower amplifier. The CMOS image sensor that is in combination with the proposed pixels and the high performance column ADC has achieved a low pixel temporal noise of 1.1 e- rms, a wide dynamic range of 87.5 dB with the video rate operation (30 Hz) and the vertical fixed pattern noise of 1.08-μ Vrms. The implemented HCG CMOS imager and WDR CMOS imager using 0.18 μm technology have the pixel conversion gain of 73.2- and 22.8-μ V e-, respectively. © 2001-2012 IEEE.


Suh S.,University of Shizuoka | Itoh S.,University of Shizuoka | Aoyama S.,Brookman Technology Inc. | Kawahito S.,University of Shizuoka
Sensors (Switzerland) | Year: 2010

For low-noise complementary metal-oxide-semiconductor (CMOS) image sensors, the reduction of pixel source follower noises is becoming very important. Column-parallel high-gain readout circuits are useful for low-noise CMOS image sensors. This paper presents column-parallel high-gain signal readout circuits, correlated multiple sampling (CMS) circuits and their noise reduction effects. In the CMS, the gain of the noise cancelling is controlled by the number of samplings. It has a similar effect to that of an amplified CDS for the thermal noise but is a little more effective for 1/f and RTS noises. Two types of the CMS with simple integration and folding integration are proposed. In the folding integration, the output signal swing is suppressed by a negative feedback using a comparator and one-bit D-to-A converter. The CMS circuit using the folding integration technique allows to realize a very low-noise level while maintaining a wide dynamic range. The noise reduction effects of their circuits have been investigated with a noise analysis and an implementation of a 1Mpixel pinned photodiode CMOS image sensor. Using 16 samplings, dynamic range of 59.4 dB and noise level of 1.9 e- for the simple integration CMS and 75 dB and 2.2 e- for the folding integration CMS, respectively, are obtained. © 2010 by the authors.


Watanabe T.,Brookman Technology Inc. | Park J.-H.,Brookman Technology Inc. | Aoyama S.,Brookman Technology Inc. | Isobe K.,Brookman Technology Inc. | Kawahito S.,University of Shizuoka
IEEE Transactions on Electron Devices | Year: 2010

A negative-bias operation of the transfer gate has revealed a major origin of dark current defects of CMOS image sensors. Charge injection from the photodiode to the substrate at the negative-bias operation has been avoided by an improved well structure. A strong visible light has been observed to cause damage with an increase in the dark current under the normal operating condition, and the damage has been annealed in the power-off mode. This indicates that the strong light possibly causes a threshold voltage shift, which is explained by the photon-assisted tunneling or emission mechanisms. Multiple stress-and-anneal cycles have been found to cause an optical hardening effect, which can be explained by immobile trapped holes. © 2006 IEEE.

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