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이창혁, Changhyuk Lee

Principal Investigator

OFFICE

L7333B

Phone

+82 10-4030-5982

EDUCATION:

Cornell University, Ithaca, NY, USA
Ph.D. in Electrical and Computer Engineering (August 2014)

Korea University, Seoul, Rep. of Korea
B.S. summa cum laude in Electrical and Computer Engineering (March 2001 – February 2005)

RESEARCH CAREER & ACTIVITIES
  • Senior Research Scientist, Center for BioMicrosystems, Brain Science Institute, Korea Institute of Science and Technology (KIST) (Jan 2018 – Present)
  • Postdoc Research Associate, Electrical and Engineering, Columbia University, New York, NY, USA  (Sept 2015 – Jan 2018)
  • Postdoc Research Associate, Electrical and Computer Engineering, Cornell University, Ithaca, NY, USA (Sept 2014 – Aug 2015)
  • Research Assistant, Electrical and Computer Engineering, Cornell University, Ithaca, NY, USA (August 2008 – August 2014)
RESEARCH INTERESTS
  • Integrated Neural Interface
    – Optoelectronic Neural Interface
    • Lens-free Implantable Fluorescence Imaging Device
    • Custom CIS (SPAD, APD) IC for Light-field Imaging
    • μLED and SPAD array on CMOS for in-vivo Fluorescence Imaging on Awake or Freely
  • Behaving Animal
    • Low-power Wireless Data and Power Connectivity for IMD
    – Mixed signal IC design for Low Power IMD
Postdocs

We are Looking For Prospective Postdocs

Postdoctoral Researcher
Graduate Students

Dmytro Kotov

Graduate student

EDUCATION
M.S. Electrical Engineering, Department of Electronics, The National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Ukraine (2017)

B.S. Electrical Engineering, Department of Electronics, The National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Ukraine (2015)

RESEARCH INTERESTS
  • Mixed signal circuit design
  • Brain-computer interface

Chaehyun Kim

Graduate Student

EDUCATION
B.S. Electronics and Electrical Engineering, Department of Engineering, Dongguk University (2018)

RESEARCH INTERESTS
  • Biomedical application of Analog/Mixed signal IC design

YuSoo Jung

Graduate Student

EDUCATION
B.S. Electronic Engineering, Department of EE, Kookmin University (2018)

RESEARCH INTERESTS
  • Bio/Medical application Analog/Mixed signal IC design
Alumni

Daniel Manwiller

Research Intern

EDUCATION
Undergraduate, Electrical Engineering, University of Michigan

RESEARCH INTERESTS
  • Digital signal processing and machine learning
  • Data analytics
Bioelectronics
Imaging Array for Lens-less FLIM

A 72×60, angle-sensitive single photon avalanche diode (A-SPAD) array for lens-less 3D fluorescence lifetime imaging. An A-SPAD pixel consists of a SPAD to provide precise photon arrival time where a time-resolved operation is utilized to avoid stimulus-induced saturation, and integrated diffraction gratings on top of the SPAD to extract incident angles of the incoming light. The combination enables mapping of fluorescent sources with different lifetimes in 3D space down to micrometer scale. Futhermore, the chip presented herein integrates pixel-level counters to reduce output data-rate and to enable a precise timing control.

Voltage Ladder Rectifier

An inductively powered, orthogonal current-reuse multi-channel amplifier for power-efficient neural recording. The power rectifier uses the input swing as a self-synchronous charge pump, making it a fully passive, full-wave ladder rectifier.

Sensors
Image Sensor for Rotation Invariant Measurement

A CMOS image sensor for efficient capture of polar symmetric imaging targets. The array uses circular photodiodes, arranged in concentric rings to capture, for example, diffraction patterns generated by optically probing a revolving MEMS device. The chip is designed with a vacant, central spot to facilitate the easy single-axis alignment of the probing illumination, target device, and detector. Imaging of high-speed rotation (>1 kfps) is made possible by dividing the array into multiple concentric bands with sectorwise addressing control.

Edge Detection Image Sensor

An all digital low-power CMOS edge detection image sensors array. Each pixel contains a voltage-controlled ring oscillator to achieve low power and cost efficient digital only edge detection. While conventional edge detection methods require high computing power as well as large chip area to process intensity maps, this work implements all-digital parallel processing algorithm that detects differences between neighboring pixel pairs on-chip, hence reducing the aforementioned power and cost overheads. In particular, a simple columnshared frequency comparator enables low power operation by eliminating arithmetic computations with large memory requirement. Such simple edge detection algorithm allows the processor area to be less than 16% of the entire image sensor, therefore maximizing the proportion of active optical area.

RF Circuits
Transceiver for FDD and TDD Operation

Although there is much active research on softwaredefined radios (SDRs) with receive (RX) or transmit (TX) functionality, little work has been done on SDR transceivers supporting frequency division duplex (FDD). In this paper, we present a new circuit concept in which a distributed TX circuit cancels the transmitted signal at a reverse RX port through destructive interference while adding signal constructively at a forward TX port. We pair the distributed transmitter with a receiver-tracking PA degeneration technique to suppress the injected noise from TX circuits in the RX band. The system does not require off-chip filters or circulators, but still achieves both SDR flexibility and both FDD and time division duplex function. Measurements from the transceiver implemented in 65-nm CMOS show a frequency tuning range of 0.3–1.6 GHz with TX–RX isolation >23 dB and transmitted power up to 19 dBm.

International Journal
Planned Baseball Outing
January 2018: Lab Opening
Information

We are a team dedicated acheiving the best in brain science research while providing an ideal environment for innovative thinking and career building skills. We are currently seeking exceptional candidates who share our passion to join our team. If you are interested in joining our Lab, please email changhyuk@kist.re.kr