scispace - formally typeset
Search or ask a question
Author

Junghyup Lee

Bio: Junghyup Lee is an academic researcher from Daegu Gyeongbuk Institute of Science and Technology. The author has contributed to research in topics: CMOS & Signal. The author has an hindex of 11, co-authored 34 publications receiving 426 citations. Previous affiliations of Junghyup Lee include Institute for Infocomm Research Singapore & KAIST.

Papers
More filters
Journal ArticleDOI
Junghyup Lee, SeongHwan Cho1
TL;DR: A trim-free low-voltage and low-power CMOS current reference which achieves high current stability to temperature variation and process-insensitive temperature compensation and employs ratio between the process-independent temperature coefficients of resistor and compensation voltage.
Abstract: This paper presents a trim-free low-voltage and low-power CMOS current reference which achieves high current stability to temperature variation. In order to achieve process-insensitive temperature compensation, the proposed circuit employs ratio between the process-independent temperature coefficients of resistor and compensation voltage. The proposed current reference is implemented in 0.18-μm CMOS technology and consumes 1.4 μW from a 1-V supply. It achieves temperature coefficient of 24.9 ppm/°C with 0 °C to 100 °C of temperature variation without trimming, which is the lowest among the recently reported CMOS current references.

75 citations

Proceedings Article
Junghyup Lee1, SeongHwan Cho1
16 Jun 2009
TL;DR: In this article, a 10MHz, 80μW reference clock oscillator is presented in 0.18μm CMOS, which employs a supply-regulated ring-oscillator in a temperature compensated feedback loop, which minimizes the frequency sensitivity to supply and temperature variations.
Abstract: A 10MHz, 80μW CMOS reference clock oscillator is presented in 0.18μm CMOS. The proposed oscillator employs a supply-regulated ring-oscillator in a temperature compensated feedback loop, which minimizes the frequency sensitivity to supply and temperature variations. The clock oscillator achieves frequency variation of less than ±0.05% against supply variation of 1.2V ~ 3V and ±0.4% against temperature variation of −20°C ~ 120°C. In addition, low power consumption is achieved by using sub-threshold bias circuits.

61 citations

Proceedings ArticleDOI
06 Mar 2014
TL;DR: A highly energy-efficient and robust wideband BCC transceiver is presented, which achieves a maximum data rate of 60Mb/s by employing a high input impedance and an equalizer at the RX front-end, and transient-detection RX architecture using differentiator-integrator combination coupled with injection-locking-based clock recovery.
Abstract: Wearable technology is opening the door to future wellness and mobile experience Following the first generation wearable devices in the form of headsets, shoes and fitness monitors, second generation devices such as smart glasses and watches are making an entrance to the market with a great potential to eventually replace the current mobile device platform eventually (Fig 3071) Wearable devices can be carried by users in a most natural way and provide all-round connectivity 24-7 without the hassle of stopping all other activities, which enables a totally different mobile experience For wearable devices, body channel communication (BCC) is an excellent alternative of conventional wireless communication through the air, to obviate the need of high-power transceivers and bulky antennas However, present BCC transceivers [1]-[5] that mainly target biomedical and sensing applications offer rather limited data rates up to 10Mb/s, which is insufficient in transferring multimedia data for emerging wearable smart devices and content-rich information for high-end medical devices (eg multi-channel neural recording microsystems) In this paper, a highly energy-efficient and robust wideband BCC transceiver is presented, which achieves a maximum data rate of 60Mb/s by employing 1) a high input impedance and an equalizer at the RX front-end, 2) transient-detection RX architecture using differentiator-integrator combination coupled with injection-locking-based clock recovery, and 3) 3-level direct digital Walsh-coded signaling at the TX

45 citations

Journal ArticleDOI
01 Nov 2016-PLOS ONE
TL;DR: It is demonstrated that independent mobility can be achieved without first training on prescribed motor movements, opening the door for the implementation of this technology in persons with tetraplegia.
Abstract: Individuals with tetraplegia lack independent mobility, making them highly dependent on others to move from one place to another. Here, we describe how two macaques were able to use a wireless integrated system to control a robotic platform, over which they were sitting, to achieve independent mobility using the neuronal activity in their motor cortices. The activity of populations of single neurons was recorded using multiple electrode arrays implanted in the arm region of primary motor cortex, and decoded to achieve brain control of the platform. We found that free-running brain control of the platform (which was not equipped with any machine intelligence) was fast and accurate, resembling the performance achieved using joystick control. The decoding algorithms can be trained in the absence of joystick movements, as would be required for use by tetraplegic individuals, demonstrating that the non-human primate model is a good pre-clinical model for developing such a cortically-controlled movement prosthetic. Interestingly, we found that the response properties of some neurons differed greatly depending on the mode of control (joystick or brain control), suggesting different roles for these neurons in encoding movement intention and movement execution. These results demonstrate that independent mobility can be achieved without first training on prescribed motor movements, opening the door for the implementation of this technology in persons with tetraplegia.

38 citations

Proceedings ArticleDOI
01 Feb 2016
TL;DR: There is a huge gap between the maximum achievable 1/f2 phase noise FOM (169dBc/Hz) and those achieved by recently proposed low-power relaxation oscillator implementations [1-4].
Abstract: Relaxation oscillators have a profound scope as on-chip reference clock sources or sensor front-ends in comparison to ring oscillators due to their superior frequency stability, control linearity, and wide tuning range. However, despite a better fundamental limit predicted in theory, the phase noise performance of relaxation oscillators trails behind that of ring oscillators. Furthermore, there is a huge gap between the maximum achievable 1/f2 phase noise FOM (169dBc/Hz) [1] and those achieved by recently proposed low-power relaxation oscillator implementations [1–4].

33 citations


Cited by
More filters
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

Journal ArticleDOI
TL;DR: Brain-machine interfaces research has been at the forefront of many neurophysiological discoveries, including the demonstration that, through continuous use, artificial tools can be assimilated by the primate brain's body schema.
Abstract: Brain-machine interfaces (BMIs) combine methods, approaches, and concepts derived from neurophysiology, computer science, and engineering in an effort to establish real-time bidirectional links bet...

373 citations

Journal ArticleDOI
TL;DR: The proposed voltage reference for use in ultra-low power systems, referred to as the 2T voltage reference, which has been demonstrated in silicon across three CMOS technologies, is proposed, showing the design exhibits comparable spreads in TC and output voltage to existing voltage references in the literature.
Abstract: Sensing systems such as biomedical implants, infrastructure monitoring systems, and military surveillance units are constrained to consume only picowatts to nanowatts in standby and active mode, respectively. This tight power budget places ultra-low power demands on all building blocks in the systems. This work proposes a voltage reference for use in such ultra-low power systems, referred to as the 2T voltage reference, which has been demonstrated in silicon across three CMOS technologies. Prototype chips in 0.13 μm show a temperature coefficient of 16.9 ppm/°C (best) and line sensitivity of 0.033%/V, while consuming 2.22 pW in 1350 μm2. The lowest functional Vdd 0.5 V. The proposed design improves energy efficiency by 2 to 3 orders of magnitude while exhibiting better line sensitivity and temperature coefficient in less area, compared to other nanowatt voltage references. For process spread analysis, 49 dies are measured across two runs, showing the design exhibits comparable spreads in TC and output voltage to existing voltage references in the literature. Digital trimming is demonstrated, and assisted one temperature point digital trimming, guided by initial samples with two temperature point trimming, enables TC <; 50 ppm/°C and ±0.35% output precision across all 25 dies. Ease of technology portability is demonstrated with silicon measurement results in 65 nm, 0.13 μm, and 0.18 μm CMOS technologies.

322 citations

Book ChapterDOI
01 Jan 2003
TL;DR: In this paper, an expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems.
Abstract: This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

207 citations

Journal ArticleDOI
01 Apr 2020
TL;DR: The development of neural interfaces, which can provide a direct, electrical bridge between analogue human nervous systems and digital man-made devices, is examined, considering challenges and opportunities created with such technology.
Abstract: Devices such as keyboards and touchscreens allow humans to communicate with machines. Neural interfaces, which can provide a direct, electrical bridge between analogue nervous systems and digital man-made systems, could provide a more efficient route to future information exchange. Here we review the development of electronic neural interfaces. The interfaces typically consist of three modules — a tissue interface, a sensing interface, and a neural signal processing unit — and based on technical milestones in the development of the electronic sensing interface, we group and analyse the interfaces in four generations: the patch clamp technique, multi-channel neural interfaces, implantable/wearable neural interfaces and integrated neural interfaces. We also consider key circuit and system challenges in the design of neural interfaces and explore the opportunities that arise with the latest technology This Review Article examines the development of neural interfaces, which can provide a direct, electrical bridge between analogue human nervous systems and digital man-made devices, considering challenges and opportunities created with such technology.

88 citations