• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.4
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• pp.318-325
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• 2008

A 1.2 V 7-bit 1 GS/s CMOS flash ADC with an interpolation factor of 4 is implemented by using a $0.13\;{\mu}m$ CMOS process. A digital calibration of DC reference voltage is proposed for the $1^{st}$ preamp array to compensate for the input offset voltage of differrential amplifiers without disturbing the high-speed signal path. A 3-stage cascaded voting process is used in the digital encoder block to eliminate the conescutive bubbles up to seven completely, if the $2^{nd}$ preamp output is assumed to have a single bubble at most. ENOB and the power consumption were measured to be 5.88 bits and 212 mW with a 195 MHz $400\;mV_{p-p}$ sine wave input.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.1 s.343
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• pp.65-70
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• 2006

An image sensor has limited dynamic range while the human eye has logarithmic response over wide range of light intensity. Although the sensor gain can be set high to identify details in darker area on the image, this results in saturation in brighter area. The gamma correction is essential to fit the human eye response. However, the digital gamma correction degrades image quality especially for darker area on the image due to the limited ADC resolution and the dynamic range. This Paper proposes a CMOS image sensor (CIS) with a nonlinear analog-to-digital converter (AU) which performs analog gamma correction. The CIS with the proposed nonlinear analog-to-digital conversion scheme was fabricated with a $0.35{\mu}m$ CMOS process. The analog gamma correction using the proposed nonlinear ADC CIS provides the 2.2dB peak-signal-to-noise-ratio(PSM) improved image qualify than conventional digital gamma correction. The PSNR of the image obtain from the digital gamma correction is 25.6dB while it is 27.8dB for analog gamma correction. The PSNR improvement over digital gamma correction is about $28.8\%$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.9 s.339
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• pp.35-40
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• 2005

A digitally controlled phase-locked loop (DCPLL) is described. The DCPLL has basically the same structure as a conventional analog PLL except for a tracking analog-to-digital converter (ADC). The tracking ADC generates the control signal for voltage controlled oscillator. Since the DCPLL employs neither digitally controlled oscillator nor time-to-digital converter-the key building blocks of digital PLL (DPLL), there is no need for the 03de-off between jitter, power consumption and silicon area. The DCPLL was implemented in a $0.18\mu$m CMOS process and the active area is 1mm $\times$0.35 mm The DCPLL consumes S9mW during the normal opuation and $984\{mu}W$ during the power-down mode from a 1.8V supply. The DCPLL shows 16.8ps ms jitter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.346-349
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• 2017

Digital image processing is widely used in a variety of areas, and noise elimination is used as the preprocessing in all the image processing processes. Degradation is occurred in the image data due to multiple reasons. Degradation is to add the noise in the image signal, and salt and pepper noise is the representative one to cause degradation. Therefore, image restoration algorithm was proposed to process with histogram weight filter and median filter by the noise density of local mask to restore the damaged image in the salt and pepper noise environment, in this article. In addition, it was compared with the existing methods using peak signal to noise ratio(PSNR) as the objective determination factor of improvement effect.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.291-298
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• 2019

In this paper, we propose a Fresnel transform method using various wavelet functions to efficiently decompose digital holograms. After implementing the proposed wavelet function-based Fresnelet transforms, we apply it to the digital hologram and analyze the energy characteristics of the coefficients. The implemented wavelet transform-based Fresnelet transform is well suited for reconstructing and processing holograms which are optically obtained or generated by computer-generated hologram technique. After analyzing the characteristics of the spline function, we discuss wavelet multiresolution analysis method based on it. Through this process, we proposed a transform tool that can effectively decompose fringe patterns generated by optical interference phenomena. We implement Fresnelet transform based on wavelet function with various decomposition properties and show the results of decomposing fringe pattern using it. The results show that the energy distribution of the coefficients is significantly different depending on whether the random phase is included or not.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.965-972
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• 2015

Along with the rapid development in digital times, image media are being used in internet, computer and digital camera. But image deterioration occurs due to various exterior reasons in the procedures of acquisition, processing, transmission and recording of digital image and major reason is noise. Therefore in order to remove salt & pepper noise, this study suggested the algorithm which replaces the noise to original pixel in case of non-noise, and processes the noise with Lagrange interpolation method in case of noise. In case high density noise was added and the noise could not be removed, noise characteristics were improved by processing the noises repeatedly. And for objective judgment, this method was compared with existing methods and PSNR(peak signal to noise ratio) was used as judgment standard.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.2
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• pp.24-29
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• 2014

Digital mammography is the most common technique for the early detection of breast cancer. To diagnose the breast cancer in early stages and treat efficiently, many image enhancement methods have been developed. This paper presents a multi-scale contrast enhancement method in the Laplacian pyramid for the digital mammogram. The proposed method decomposes the image into the contrast measures by the Gaussian and Laplacian pyramid, and the pyramid coefficients of decomposed multi-resolution image are defined as the frequency limited local contrast measures by the ratio of high frequency components and low frequency components. The decomposed pyramid coefficients are modified by the contrast measure for enhancing the contrast, and the final enhanced image is obtained by the composition process of the pyramid using the modified coefficients. The proposed method is compared with other existing methods, and demonstrated to have quantitatively good performance in the contrast measure algorithm.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.3
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• pp.162-168
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• 2013

This paper examines the implementation of automatic compensation modules for digital camera image when a person is closing his/her eyes. The modules detect the face and eye region and then recognize the eye state. If the image is taken when a person is closing his/her eyes, the function corrects the eye and produces the image by using the most satisfactory image of the eye state among the past frames stored in the buffer. In order to recognize the face and eye precisely, the pre-process of image correction is carried out using SURF algorithm and Homography method. For the detection of face and eye region, Haar-like feature algorithm is used. To decide whether the eye is open or not, similarity comparison method is used along with template matching of the eye region. The modules are tested in various facial environments and confirmed to effectively correct the images containing faces.

• Journal of Biomedical Engineering Research
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• v.21 no.3 s.61
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• pp.255-260
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• 2000

This paper presents a radio-telemetry patient monitor. which is used for intensive cal?e units. emergency and surgical operation rooms to monitor continuously patients' vital signs. The radio-telemetry patient monitor consists of a vital sign acquisition unit. wireless data transmission units and a vital sign-monitoring unit. The vital sign acquisition unit amplifies biological signals, performs analog signal to serial digital data conversion using the one chip micro-controller. The converted digital data is modulated FSK in UHF band using low output power and transmitted to a remote site in door. In comparison with analog modulation. FSK has major advantages to improve performance with respect to noise resistance with fower error and the potential ability to process and Improve quality of the received data. The vital sign-monitoring unit consists of the receiver to demodulate the modulated digital data, the LCD monitor to display vital signs continuously and the thermal head printer to record a signal.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.8-16
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• 2020

In this paper, a single-bit 2nd-order delta-sigma modulator with the architecture of cascaded-of-integrator feedforward (CIFF) is proposed for column-parallel analog-to-digital converter (ADC) array used in a low noise CMOS image sensor. The proposed modulator implements two switched capacitor integrators and a single-bit comparator within only 10-㎛ column-pitch for column-parallel ADC array. Also, peripheral circuits for driving all column modulators include a non-overlapping clock generator and a bias circuit. The proposed delta-sigma modulator has been implemented in a 110-nm CMOS process. It achieves 88.1-dB signal-to-noise-and-distortion ratio (SNDR), 88.6-dB spurious-free dynamic range (SFDR), and 14.3-bit effective-number-of-bits (ENOB) with an oversampling ratio (OSR) of 418 for 12-kHz bandwidth. The area and power consumption of the delta-sigma modulator are 970×10 ㎛2 and 248 ㎼, respectively.