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Minkyu Je

Bio: Minkyu Je is an academic researcher from KAIST. The author has contributed to research in topics: CMOS & Amplifier. The author has an hindex of 32, co-authored 302 publications receiving 3903 citations. Previous affiliations of Minkyu Je include Singapore Science Park & Institute for Infocomm Research Singapore.


Papers
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Journal ArticleDOI
TL;DR: A new wireless power transfer technique using optimal resonant load transformation is presented with significantly improved efficiency at the cost of only one additional chip inductor component, which is suitable for batch production, as well as biocompatible owing to no incorporation of ferromagnetic core.
Abstract: Wireless power transfer provides a safe and robust way for powering biomedical implants, where high efficiency is of great importance A new wireless power transfer technique using optimal resonant load transformation is presented with significantly improved efficiency at the cost of only one additional chip inductor component The optimal resonant load condition for the maximized power transfer efficiency is explained The proposed technique is implemented using printed spiral coils with discrete surface mount components at 1356 MHz power carrier frequency With an implantable coil having an area of 25 mm × 10 mm and a thickness of 05 mm, the power transfer efficiency of 58% is achieved in the tissue environment at 10-mm distance from the external coil Compared to previous works, the power efficiency is much higher and the structure is compact with planar integration, easy to tune, and suitable for batch production, as well as biocompatible owing to no incorporation of ferromagnetic core

276 citations

Journal ArticleDOI
TL;DR: In this paper, a simple and accurate parameter-extraction method of a high-frequency small-signal MOSFET model including the substrate-related parameters and non-reciprocal capacitors is proposed.
Abstract: A simple and accurate parameter-extraction method of a high-frequency small-signal MOSFET model including the substrate-related parameters and nonreciprocal capacitors is proposed. Direct extraction of each parameter using a linear regression approach is performed by Y-parameter analysis on the proposed equivalent circuit of the MOSFET for high-frequency operation. The extracted results are physically meaningful and good agreement has been obtained between the simulation results of the equivalent circuit and measured data without any optimization. Also, the extracted parameters, such as g/sub m/ and g/sub ds/, match very well with those obtained by DC measurement.

134 citations

Journal ArticleDOI
TL;DR: A prototype wireless capsule endoscopy using the proposed transceiver demonstrated in vivo image transmission of 640 × 480 resolution at a frame rate of 2.5 frames/s with 10 Mb/s data rate.
Abstract: An integrated CMOS ultrawideband wireless telemetry transceiver for wearable and implantable medical sensor applications is reported in this letter. This high duty cycled, noncoherent transceiver supports scalable data rate up to 10 Mb/s with energy efficiency of 0.35 nJ/bit and 6.2 nJ/bit for transmitter and receiver, respectively. A prototype wireless capsule endoscopy using the proposed transceiver demonstrated in vivo image transmission of 640 × 480 resolution at a frame rate of 2.5 frames/s with 10 Mb/s data rate.

131 citations

Journal ArticleDOI
TL;DR: In this paper, the design of a novel differentially fed dual-band implantable antenna operating at 402-405 MHz Medical Implant Communication Services (MICS) band and 2.4-2.5 GHz Industrial, Scientific, and Medical (ISM) band is introduced.
Abstract: The design of a novel differentially fed dual-band implantable antenna operating at 402-405 MHz Medical Implant Communication Services (MICS) band and 2.4-2.5 GHz Industrial, Scientific, and Medical (ISM) band is introduced. The proposed implanted antennas are for both planar and flexible implantation scenarios. Biocompatible material parylene-C is adopted to cover the implanted antenna. The size of the proposed antennas including the encapsulation for planar and flexible case is 179.0 mm3 and 186.3 mm3 respectively. The Specific Absorption Rate (SAR) distribution and the radiation pattern at both frequencies induced by the implanted antenna are evaluated. The performance of the communication link between the implanted antenna and an external half-wavelength dipole at two resonant frequencies is also presented. In vitro test in minced pork is performed to test the reliability of the antenna in the real implantation cases.

128 citations

Journal ArticleDOI
TL;DR: A dual sample-and-hold architecture is proposed, which extends the sampling time of the ADC and reduces the average power per channel by more than 50% compared to the conventional multiplexing neural recording system.
Abstract: This paper presents a fully implantable 100-channel neural interface IC for neural activity monitoring. It contains 100-channel analog recording front-ends, 10 multiplexing successive approximation register ADCs, digital control modules and power management circuits. A dual sample-and-hold architecture is proposed, which extends the sampling time of the ADC and reduces the average power per channel by more than 50% compared to the conventional multiplexing neural recording system. A neural amplifier (NA) with current-reuse technique and weak inversion operation is demonstrated, consuming 800 nA under 1-V supply while achieving an input-referred noise of 4.0 μVrms in a 8-kHz bandwidth and a NEF of 1.9 for the whole analog recording chain. The measured frequency response of the analog front-end has a high-pass cutoff frequency from sub-1 Hz to 248 Hz and a low-pass cutoff frequency from 432 Hz to 5.1 kHz, which can be configured to record neural spikes and local field potentials simultaneously or separately. The whole system was fabricated in a 0.18-μm standard CMOS process and operates under 1 V for analog blocks and ADC, and 1.8 V for digital modules. The number of active recording channels is programmable and the digital output data rate changes accordingly, leading to high system power efficiency. The overall 100-channel interface IC consumes 1.16-mW total power, making it the optimum solution for multi-channel neural recording systems.

121 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications, with regard to network applications and discuss open issues and challenges in implementing wireless charging technologies.
Abstract: Wireless charging is a technology of transmitting power through an air gap to electrical devices for the purpose of energy replenishment. The recent progress in wireless charging techniques and development of commercial products have provided a promising alternative way to address the energy bottleneck of conventionally portable battery-powered devices. However, the incorporation of wireless charging into the existing wireless communication systems also brings along a series of challenging issues with regard to implementation, scheduling, and power management. In this paper, we present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications. In particular, with regard to network applications, we review the static charger scheduling strategies, mobile charger dispatch strategies and wireless charger deployment strategies. Additionally, we discuss open issues and challenges in implementing wireless charging technologies. Finally, we envision some practical future network applications of wireless charging.

718 citations

Journal ArticleDOI
TL;DR: The quality of intervention studies intended to increase hand hygiene compliance remains disappointing and although multifaceted campaigns with social marketing or staff involvement appear to have an effect, there is insufficient evidence to draw a firm conclusion.

503 citations

Journal ArticleDOI
Hongchang Li1, Jie Li1, Kangping Wang1, Wenjie Chen1, Xu Yang1 
TL;DR: In this paper, a maximum efficiency point tracking control scheme is proposed to maximize the system efficiency while regulating the output voltage, which is unique and prominent in that it fixes the operating frequency at the receiving-side resonant frequency and converts both the input voltage and the load resistance at the same time.
Abstract: With a good balance between power transfer distance and efficiency, wireless power transfer (WPT) using magnetic resonant coupling is preferred in many applications. Generally, WPT systems are desired to provide constant output voltage with the highest possible efficiency as power supplies. However, the highest efficiency is not achieved by the reported closed-loop WPT systems that maintain constant output voltage against coupling and load variations. In this paper, an efficiency evaluation method is put forward to evaluate the closed-loop control schemes. Furthermore, a maximum efficiency point tracking control scheme is proposed to maximize the system efficiency while regulating the output voltage. This control scheme is unique and prominent in that it fixes the operating frequency at the receiving-side resonant frequency and converts both the input voltage and the load resistance at the same time. Thus, the maximum efficiency point on the constant output voltage trajectory can be tracked dynamically. Therefore the system's output voltage can be maintained constant and its efficiency is always the highest. The experimental results show that the maximum efficiency point is tracked and a very high overall efficiency is achieved over wide ranges of coupling coefficient and load resistance.

463 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a wideband ultra wideband (UWB) communication protocol with a low EIRP level (−41.3dBm/MHz) for unlicensed operation between 3.1 and 10.6 GHz.
Abstract: Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.

452 citations