A5031381464- Analog and Mixed-Signal Circuit Design
- Energy Harvesting in Wireless Networks
- Advanced MEMS and NEMS Technologies
- Analytical Chemistry and Sensors
- Radio Frequency Integrated Circuit Design
- CCD and CMOS Imaging Sensors
- Innovative Energy Harvesting Technologies
- Advancements in PLL and VCO Technologies
- Advanced Battery Technologies Research
- Photonic and Optical Devices
- Neuroscience and Neural Engineering
- Advanced Memory and Neural Computing
- Sensor Technology and Measurement Systems
- Low-power high-performance VLSI design
- Mechanical and Optical Resonators
- Speech and Audio Processing
- Acoustic Wave Resonator Technologies
- Modular Robots and Swarm Intelligence
- Image Retrieval and Classification Techniques
- Multimodal Machine Learning Applications
- Advancements in Battery Materials
- Music and Audio Processing
- Wireless Power Transfer Systems
- Gas Sensing Nanomaterials and Sensors
- Domain Adaptation and Few-Shot Learning
Seoul National University
2025
University of Michigan
2015-2024
Pusan National University
2023
Yonsei University
2019-2022
Sun Yat-sen University
2021
Memorial Hospital
2021
Tongji Hospital
2021
Gangnam Severance Hospital
2021
Fujitsu (Japan)
2019
Korea University
2017
We propose a fully-integrated temperature sensor for battery-operated, ultra-low power microsystems. Sensor operation is based on independent/dependent current sources that are used with oscillators and counters to generate digital code. A conventional approach these currents drop sensitive voltage across resistor. Since large resistance required achieve nWs of consumption typical levels (100 s mV 1 V), we introduce new sensing element outputs only 75 save both area. The implemented in 0.18...
The Internet of Things (IoT) is a rapidly emerging application space, poised to become the largest electronics market for semiconductor industry. IoT devices are focused on sensing and actuating our physical environment have nearly unlimited breadth uses. In this paper, we explore space then identify two common challenges that exist across space: ultra-low power operation system design using modular, composable components. We survey recent low techniques discuss bus enables modular design....
Capacitance sensors are widely used to measure various physical quantities, including position, pressure, and concentration of certain chemicals [1-6]. Integrating capacitive into a small wireless sensor system is challenging due their large power consumption relative the total power/energy budget, which can be as low few nW [4]. Typical capacitance-to-digital converters (CDCs) use charge sharing or transfer between capacitors convert sampled capacitance voltage, then measured with an ADC...
This paper presents a new energy-efficient ring oscillator collapse-based comparator, named edge-pursuit comparator (EPC). automatically adjusts the performance by changing comparison energy according to its input difference without any control, eliminating unnecessary spent on coarse comparisons. Furthermore, detailed analysis of EPC in phase domain shows improved efficiency over conventional comparators even scaling, and wider resolution tuning capability with small load capacitance area....
We present a 2×4×4mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> imaging system complete with optics, wireless communication, battery, power management, solar harvesting, processor and memory. The features 160×160 resolution CMOS image sensor 304nW continuous in-pixel motion detection mode. System components are fabricated in five different IC layers die-stacked for minimal form factor. Photovoltaic (PV) cells face the opposite...
This work presents an ultra-low-power oscillator designed for wake-up timers in compact wireless sensors. In a conventional relaxation oscillator, capacitor periodically resets to fixed voltage using continuous comparator, thereby generating output clock. The reset is triggered by comparator and thus the clock period dependent on delay of which therefore needs be fast compared period, making this approach power hungry. To avoid penalty constant charge subtraction scheme proposed paper. As...
Acoustic sensing is one of the most widely used modalities to intelligently assess environment. In particular, ultra-low power (ULP) always-on voice activity detection (VAD) gaining attention as an enabling technology for IoT platforms. many practical applications, acoustic events-of-interest occur infrequently. Therefore, system consumption typically dominated by wakeup detector, while remainder power-gated vast majority time. A previous detector [1] consumed just 12nW but could not process...
This paper presents an ultra-low power acoustic sensing and object recognition microsystem for Internet of Things applications. The is targeted unattended ground sensor nodes where long-term (decades) life time desired without the need battery replacement. system incorporates microelectromechanical systems microphone as a frontend along with active circuitry to identify target objects. We introduce algorithm-circuit cross optimization realize 12-nW stand-alone that integrates analog digital...
Miniaturized computing platforms typically operate under restricted battery capacity due to their size [1]. Due low duty cycles in many sensing applications, sleep-mode power can dominate the total energy budget. Wakeup timers are a key always-on component such sleep modes and must therefore be designed with aggressive consumption targets (e.g., <;10nW). Also, accurate timing generation is critical for peer-to-peer communication between sensor Although 32kHz crystal oscillator provide [2]...
Energy-optimal operation is one of the key requirements Internet-of-Things (IoT) applications to increase battery life. In this article, using a combination dynamic voltage scaling (DVS) and adaptive body biasing (ABB), energy-optimal achieved with given fixed operating frequency determined by application demands. Based on observation that ratio leakage power can be an accurate indicator for optimal point, proposed method dynamically tracks minimum energy points adjusting supply bias very...
This article presents a voice and acoustic activity detector that uses mixer-based architecture ultra-low-power neural network (NN)-based classifier. By sequentially scanning 4 kHz of frequency bands down-converting to below 500 Hz, feature extraction power consumption is reduced by 4×. The NN processor employs computational sprinting, enabling 12× reduction. system also features inaudible signature detection for intentional remote silent wakeup the while re-using subset same components....
As Internet-of-Things (IoT) systems proliferate, there is a greater demand for small and efficient power management units. Fully integrated switched-capacitor (SC) DC-DC converters are promising candidates due to their form factor low quiescent power, aided by dynamic activity scaling [1-3]. However, they offer limited number of conversion ratios, making them challenging use in actual since often require multiple output voltages (to reduce consumption) various input sources maximize...
Wireless power transfer for implantable systems must harvest very low levels due to incident on human tissues and a small receiver coil size. This work proposes resonant current-mode charging reduce minimum harvestable input increase efficiency at levels. Avoiding rectification voltage regulation from conventional voltage-mode methods, this resonates an LC tank multiple cycles build up energy, then directly charges battery with inductor current. A prototype is fabricated in 0.18 μm CMOS...
Continuous health monitoring has become feasible, largely due to miniature implantable sensor systems such as [1]. To recharge batteries of systems, wireless power transfer is a popular option since it non-invasive. However, there are two main challenges: 1) strict safety regulations incident on human tissue; 2) small coil size for better biocompatibility. These issues reduce the received at coil, make difficult obtain sufficient implanted devices, and call high power-efficiency...
A self-sustainable sensing platform powered entirely by small-scale benthic microbial fuel cells (MFCs) for oceanic applications is presented. An ultra-low power chip featuring an ARM Cortex-M0 processor, 3 kB of SRAM, and management unit (PMU) designed to consume 11 nW in sleep mode perpetual operation. The PMU includes a switched-capacitor DC/DC converter efficient energy harvesting step-down conversion wide range input output power. MFC with 21.3 cm <sup...
IoT devices are becoming increasingly intelligent and context-aware. Sound is an attractive sensory modality because it information-rich but not as computationally demanding alternatives such vision. New applications of ultra-low power (ULP), 'always-on' acoustic sensing includes agricultural monitoring to detect pests or precipitation, infrastructure health tracking recognize symptoms, security/safety identify dangerous conditions. A major impediment for the adoption always-on,...
Present cancer treatments using chemotherapy are limited owing to both significant side effects normal cells and high recurrence rates. In this study, we demonstrated cell-targeting nanoparticles that load multiple anticancer agents for specific substantial therapeutic effects. For purpose, hyaluronic acid (HA) was conjugated mesoporous silica (MSNs) specifically targeting cells. Moreover, the prepared HA-MSNs exhibited drug loading potential sustained release. Compared bare MSNs, were...
This article proposes StiMote, an untethered, free-floating and individually addressable stimulator mote designed for visual cortex stimulation, aimed at vision restoration. The system is optically powered by a custom photovoltaic (PV) layer. In addition, the photodiode (PD) layer captures light modulation forwards it to optical receiver (ORX) including tranimpedance amplifier. Translated instructions can assign unique slot, up 1024 available, each within time-division multiple access (TDMA)...
Small form-factor piezoresistive MEMS sensors, often configured in a Wheatstone bridge, are widely used to measure physical signals such as pressure [1-3], temperature [4], force [1], and gas concentration. A common method realize digital output from the bridge involves biasing with DC voltage source using low-noise amplifier followed by an ADC. While measurement can achieve high resolution linearity, it is very power hungry [3] because resistance low (typically 1–10kΩ). Both instantaneous...
Wireless sensors for IoT applications have become a prominent computing class and are typically severely power constrained. devices deployed in wide range of environments low consumption must be guaranteed across temperature range. The combination dynamic voltage scaling (DVS) adaptive body biasing (ABB) can achieve minimum total energy per cycle, where leakage at an optimal trade-off point [1]. However, due to the dependence on workload fluctuations over time, this operating requires...
We propose a temperature sensor using novel process-invariant sensing element and voltage to current converter for battery-operated ultra-low power micro systems. By introducing new temperature-to-voltage that outputs only 75mV, the achieves power. The was implemented in 180nm CMOS process uses 0.09mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of area. Measurements from test chips show 65nW consumption, lowest reported date, with an...
Programmability is one of the most significant advantages a digital phase-locked loop (PLL) compared with charge-pump PLL. In this paper, PLL that extends programmability to include noise introduced. A digitally controlled oscillator (DCO) using switched capacitor for frequency feedback proposed maintain constant figure merit while reconfiguring its performance. The DCO offers an accurate and linear tuning curve insensitive environmental changes. detection circuit statistical property...
Digital PLLs are popular for on-chip clock generation due to their small size and technology portability. Variability tolerance is a key design challenge when designing such in an advanced CMOS technology. Environmental variations, as mismatch, process, supply voltage, temperature (PVT) perturb device characteristics result performance changes, DCO gain noise. Another consideration the wide range of operating modes which modern digital circuits (e.g., processors) operate. For instance,...