• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.769-772
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• 2005

This paper describes a low-voltage and low-power channel selection analog front end with continuous-time low pass filters and highly linear programmable-gain amplifier(PGA). The filters were realized as balanced Gm-C biquadratic filters to achieve a low current consumption. High linearity and a constant wide bandwidth are achieved by using a new transconductance(Gm) cell. The PGA has a voltage gain varying from 0 to 65dB, while maintaining a constant bandwidth. A filter tuning circuit that requires an accurate time base but no external components is presented. With a 1-Vrms differential input and output, the filter achieves -85dB THD and a 78dB signal-to-noise ratio. Both the filter and PGA were implemented in a 0.18um 1P6M n-well CMOS process. They consume 3.2mW from a 1.8V power supply and occupy an area of $0.19mm^2$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.1
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• pp.52-58
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• 2009

A low voltage, low power delta-sigma modulator is proposed for cardiac pacemaker applications. A cascade of delta-sigma modulator stages that employ a feedforward topology has been used to implement a high-resolution oversampling ADC under the low supply. An inverter-based switched-capacitor circuit technique is used for low-voltage operation and ultra-low power consumption. An experimental prototype of the proposed circuit has been implemented in a $0.35-{\mu}m$ CMOS process, and it achieves 61-dB SNDR, 63-dB SNR, and 65-dB DR for a 120-Hz signal bandwidth at 7.6-kHz sampling frequency. The power consumption is only 280 nW at 1-V power supply.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.11
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• pp.9-17
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• 2011

As semiconductor process rapidly developed, the density of chips becomes higher and the space between adjacent lines narrows smaller. This trend increases the capacitance and inductance in interconnects and the coupling-capacitance of adjacent lines grows even bigger than the self-capacitance of themselves, especially in global interconnects. Inductive and capacitive coupling observed in these phenomena may cause serious problems in signal integrity. This paper proposes a codeword generation technique using extra interconnect lines to reduce the crosstalk caused by inductive and capacitive coupling and to reduce dynamic power consumption considering probability of input data. To estimate the performance of the proposed technique, the experimental results have been obtained using FastCap, FastHenry and HSPICE, and it has been shown that the power consumption using the proposed technique has yielded approximately 15% less than the results of the previous technique.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.11
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• pp.48-56
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• 2011

Novel class-A bipolar current conveyor($CCII{\pm}$) with differential current output and its application to output current controllable CCII+ for electronic tuning systems are designed. The $CCII{\pm}$ is consists of conventional CCII+ and complementary cross current sources. The CCII+ with controllable the output current consists of the $CCII{\pm}$ and a current gain amplifier with single-ended current output. The simulation result shows that the $CCII{\pm}$ has current input impedance of $1.9{\Omega}$ and a good linearity for voltage and current follower. The proposed CCII+ has 3-dB cutoff frequency of 10MHz for the range over bias control current $100{\mu}A$ to 10mA. The range of output current control is four decade. The power dissipation of the CCII+ is 4.5mW at supply voltage of ${\pm}2.5V$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.11
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• pp.63-70
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• 2008

In this paper, a smart sensor system for the MEMS pressure sensor was developed. A compensation algorithm and programmable calibration circuits were presented to eliminate errors caused by temperature drift of piezoresistive pressure sensors in itself. This system consisted of signal conditioning, calibration, temperature detection, microprocessor, and communication parts and these were integrated into a SOC. A RS-232 interface was employed for monitoring and control of a smart sensor system. The area of fabricated IC is $4.38{\times}3.78\;mm^2$ and a $0.35{\mu}m$ high voltage CMOS process was used. Compensation error for temperature drift of 50 KPa pressure sensors was measured into ${\pm}0.48%$ in the range of $-40^{\circ}C{\sim}150^{\circ}C$. Total power consumption was 30.5 mW.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.42-48
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• 2007

In x-ray imaging system, two kinds of noises are involved. First, the charge generated from the radiation interaction with the detector during exposure. Second, the signal is then added by readout electronics noise. But, x-ray images are not modeled by Gaussian noise but as the realization of a Poisson process. In this paper, we apply a new approach to remove Poisson noise from medical X-ray image in the wavelet domain, the applied methods shows more excellent results in cone-beam CT.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.86-93
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• 2008

A low-power, low-noise, highly-linear hybrid balun circuit is proposed for 2.4-GHz fully differential CMOS direct conversion receivers. The hybrid balun is composed of a passive transformer and loss-compensating auxiliary amplifiers. Design issues regarding the optimal signal splitting and coupling between the transformer and compensating amplifiers are discussed. Implemented in $0.18{\mu}m$ CMOS process, the 2.4 GHz hybrid balun achieves 2.8 dB higher gain and 1.9 dB lower noise figure than its passive counterpart and +23 dBm of IIP3 only at a current consumption of 0.67 mA from 1.2 V supply. It is also examined that the hybrid balun can remarkably lower the total noise figure of a 2.4 GHz fully differential RF receiver only at a cost of 0.82 mW additional power dissipation.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.69-79
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• 1999

The research and implementation was preformed on high-resolution CCTV camera with CCD exclusive DSP conventional analog signal processor CCTV camera has its limit on auto exposure(AE), auto white balance(AWB), back light compensation(BLC) processing, severe distortion and noise of image, manual control parameter setting, etc. In our study, to resolve the problems in conventional CCTV camera, we made it possible to control AE, AWB, BLC automatically by the use of the DSP, which are used exclusively in the CCD camera produced domestically, and the microcontroller. And we utilized the function of screen display of microcontroller for the user-friendly interface to control CCD camera. And the electronic variable resister(EVR) was used to avoid setting parameters manually in the level of manufacturing process. As the result, It became possible to control parameters of the camera by program. And the cost-down effect was accomplished by improving the reliability of parameter values and reducing the efforts in setting parameters.

• KIISE Transactions on Computing Practices
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• v.23 no.7
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• pp.434-439
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• 2017

More and more people are suffering from sleep disturbance, which can have many different causes. The healthcare industry, which can help people with this disability, is one technology that is currently in the spotlight. However, current services are vulnerable to data concentration, because they are simple telemedicine services that transmit all data to a remote server and process the data on the server. They have a disadvantage in that the data cannot be streamed in real time by synchronizing the biometric data of remotely protected persons. In order to solve this problem, we propose a service structure for streaming biometric data of protected persons to a hospital or guardian in real time, using a self-organizing distributed middleware platform without a central server. We prove that it is possible to provide an effective streaming service by evaluating the service start time and average delay time.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.6-10
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• 2015

RF energy harvesting technology is a promising technology for generating the electrical power from ambient RF signal to operate low-power consumption devices(eg. sensor) in wireless communication networks. This paper, motivated by this and building upon existing CR(Cognitive Radio) network model, proposes a optimal control policy for RF energy harvesting CR networks model where secondary users that have low power consumption harvest ambient RF energy from transmission by nearby active primary users, while periodically sensing and opportunistically accessing the licensed spectrum to the primary user's network. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.