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Non-contact Pulse-based Radar with an Excited RF Pulse Generator for Vital-sign Application
(2019-01-01)
Chen, Wei-Hsien
;
Chang, Chia-Hung
;
Kuo, Chien-Nan
;
Hsu, Chia-Chin
;
電子工程學系及電子研究所
This paper presents a pulse-based investigation to generate a serial of sensing pulses for probing the reciprocal movements of heartbeat and chest, respectively. An excited self-contained RF pulse generator with digital assisted controller is used for pulse shaping and performing nanosecond sensing pulses. In addition, the generator is implemented by a common source field-controlled transistor and a contour circuit by micro-strip line. Hence, in this paper, probing pulses and receives the echoes from the investigated subject back and forth by the whole sensing radar based on the monostatic antenna system. The demodulator is utilized to perform the multiplication of the reference probing waves and the return echoes delayed by the time interval between the emitted signal and reflected waves back to the radar module. The following analog baseband processing circuits with 3-stage topology for further amplifying and filtering the received physiological information help to increase the overall signal-to-noise ratio (SNR). The measured results demonstrate that the radiated RF pulses and vital signs are expected.
Long-Term Performance Studies of a LoRaWAN-based PM2.5 Application on Campus
(2018-01-01)
Wang, Shie-Yuan
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Zou, Ji-Jhe
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Chen, Yo-Ru
;
Hsu, Chun-Chia
;
Cheng, Yu-Hsiang
Recently, LoRa/LoRaWAN has been proposed as a promising LPWAN technology for Internet-of-Things (IoT) applications. For monitoring the long-term PM2.5 air quality on our campus, starting from February 1 2017, we have set up a LoRaWAN-based PM2.5 air quality monitoring system on our campus. In total, twenty-two PM2.5 sensor devices have been operating at the rooftop of buildings or on the lamp poles since then. Each of these PM2.5 sensor devices uses a LoRaWAN module to send its most recent PM2.5 value to the LoRaWAN gateway every 72 seconds. After being received successfully by the LoRaWAN gateway, the packets carrying these values were stored into a database with their SNR/RSSI information. With the sequence numbers added by our PM2.5 application running on each device, the packets stored in the database provide many important information about the long-term packet loss rate performance of LoRaWAN on campus. In this paper, we process these data to report real long-term performance of LoRaWAN when used on campus.
Vital-Sign Processing Receiver With Clutter Elimination Using Servo Feedback Loop for UWB Pulse Radar System
(2020-01-01)
Chang, Chia-Hung
;
Chen, Wei-Hsien
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This brief presents a vital-sign processing circuit for simultaneous dc/near-dc elimination and out-of-band interference rejection without any digital signal processing or algorithm assistance for the ultrawideband (UWB) pulse-based radar system. An intrinsic self-balanced MOS diode (SBMD) was proposed as a stable and balanced pseudo resistor applied under a servo feedback loop in a vital-sign receiver of the sensing radar to perform as a high-pass filter (HPF) with an ultralow corner frequency lower than 0.5 Hz for removing undesired clutters of the reflected signals and input dc-offset voltages from innate circuit offsets. A third-order switched-capacitor (SC) Chebyshev low-pass filter (LPF) with leap-frog topology as the subsequent stage was adopted to suppress the out-band noises, thereby establishing an integrated vital-sign processing circuit with bandpass frequency response and incorporating it into a radar module to verify its viability.
A charge accumulation-free voltage-controlled functional electrical stimulator with bi-phasic sinusoidal stimulation
(2019-11-01)
Chen, Wei-Hsien
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Chang, Chia-Hung
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Shih, Horng-Yuan
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Chiu, Tzai-Wen
;
Kuo, Chien-Nan
This paper presents a charge accumulation-free voltage-controlled (VC) bi-phasic sinusoidal functional electrical stimulator (FES) for bioelectronic application. Traditionally, constant current (CC) pulse-shaped FESs with active or passive charge balancers are used to compensate for accumulated charges arise from process, voltage and temperature (PVT) variation as a result of long-term stimulation. Unlike the CC pulse-shaped FES, the VC sinusoidal-shaped FES is adopted here to avoid charge accumulation over time. The charge balancer is not required, substantially reducing system complexity and the chip area of the FES. To demonstrate the feasibility of concept, in this paper, four channels of VC bi-phasic sinusoidal-shaped FESs are integrated with the bio-potential recording circuit to compare with four channels of CC bi-phasic pulse-shaped FESs that are integrated with the same neural recording system for comparison. Measurements indicate an absence of charge accumulation as a result of the VC FESs. In addition, here we adopt the sinusoidal stimulation to reduce transient effects on tissue in comparison to a pulse-shaped method. The bio-potential activities of a cockroach leg that is stimulated for 50 s by the proposed bi-phasic sinusoidal stimulation are recorded. The measured bio-potential activities of a cockroach leg show that no stimulation-evoked leg movement occurs under stimulation by the sinusoidal waveform.
Nanocontact disorder in InP nanowire devices for the enhancement of visible light and oxygen gas sensitivities
(2017-01-01)
Lin, Yen-Fu
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Chang, Chia-Hung
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Hung, Tsu-Chang
;
Liu, Zhaoping
;
Fang, Jiye
InP nanowires, synthesized through a self-seeded growth approach, are used in the fabrication of field-effect transistors which consist of source, drain, and back-gate electrodes. The weak gating voltage dependence implies low carrier concentrations whereas its behavior reveals native n-type doping in InP nanowires. These InP nanowire devices exhibit a vast variation of room-temperature resistance that raises a question about contact resistance. For devices of low room-temperature resistance, electron transport in InP nanowires is investigated using temperature dependent resistance in the temperature range between 80 and 300 K, and it can be analyzed using the model of thermal activation. For other devices of high room-temperature resistance, we take into account nanocontact resistance. Models of both Schottky contact and Mott's variable range hopping (VRH) are considered. The two resistances are connected in parallel to give total contact resistance of InP nanowire devices. After fitting experimental data by the proposed model, we estimate effective Schottky barriers and disorder contributions to nanocontact resistance. The effective Schottky barrier, and the nanocontact Schottky and Mott's VRH resistances are plotted as a function of the device room-temperature resistance which indicates the scale of disorder. Using room-temperature resistance of InP nanowire devices, the devices are classified into nanowire-or contact-dominated devices. The two different class of devices are used to check their photo-and gas-sensitivities. The contact-dominated InP nanowire devices show low dark current and low photocurrent as usual, but these contact-dominated devices give high ratio of photo-to dark-current. That result reveals a high photo-sensitivity for those devices of high nanocontact resistance. On the other hand, for gas sensing experiments, the contact-dominated devices show as well a high ratio of resistance under O-2 to that under N-2 gas exposure. (C) 2017 The Authors. Published by Elsevier B.V.
Nanocontact Disorder in Nanoelectronics for Modulation of Light and Gas Sensitivities
(2015-08-11)
Lin, Yen-Fu
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Chang, Chia-Hung
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Hung, Tsu-Chang
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Jian, Wen-Bin
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Tsukagoshi, Kazuhito
To fabricate reliable nanoelectronics, whether by top-down or bottom-up processes, it is necessary to study the electrical properties of nanocontacts. The effect of nanocontact disorder on device properties has been discussed but not quantitatively studied. Here, by carefully analyzing the temperature dependence of device electrical characteristics and by inspecting them with a microscope, we investigated the Schottky contact and Mott's variable-range-hopping resistances connected in parallel in the nanocontact. To interpret these parallel resistances, we proposed a model of Ti/TiOx in the interface between the metal electrodes and nanowires. The hopping resistance as well as the nanocontact disorder dominated the total device resistance for high-resistance devices, especially at low temperatures. Furthermore, we introduced nanocontact disorder to modulate the light and gas responsivities of the device; unexpectedly, it multiplied the sensitivities compared with the intrinsic sensitivity of the nanowires. Our results improve the collective understanding of electrical contacts to low-dimensional semiconductor devices and will aid performance optimization in future nanoelectronics.
On Investigation of Near-field Antenna for Pulse based Vital-sign Monitoring Application
(2018-01-01)
Chang, Chia-Hung
;
Hung, Wei-Ping
;
電信工程研究所
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Institute of Communications Engineering
This paper presents a pulsed-based vital-sign monitoring system using a comb-shaped antenna for wearable application. Two prototypes of near-field antenna are designed to investigate the performance of the received physiological signal on the wrist artery of a subject. The real-time, non-contact, and compact sensing module is analyzed, designed, and implemented.
Performance of LoRa-based IoT Applications on Campus
(2017-01-01)
Wang, Shie-Yuan
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Chen, Yo-Ru
;
Chen, Tzu-Yang
;
Chang, Chia-Hung
;
Cheng, Yu-Hsiang
To promote smart campus, National Chiao Tung University is deploying several location-based IoT applications based on wireless communications technologies including LoRa and NB-IoT. The applications are indoor/outdoor environment conditions monitoring (such as PM2.5, temperature, and humidity), emergency buttons, and so on. This paper uses PM2.5 measurement application as an example to present the performance of LoRa when it is used on campus. We investigated the LoRa transmission performance from LoRa end-devices to the LoRa gateway. We show how packet losses were affected by the distance between the end-device and the gateway, the transmit power, the payload length, the antenna angle, the time of day, and the weather conditions. The pattern of LoRa packet losses were also measured and we found that in our long-term PM2.5 monitoring application, more than 99% of LoRa packet losses occurred with three or less consecutive packet losses.
Application of Smart Appliances to Wireless Area Network and Module Development
(2017-01-01)
Hung, Wei-Ping
;
Lee, Tsern-Huei
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Chang, Chia-Hung
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, we implement the Wi-Fi hardware architecture. The core chip designed by the MediaTek Corporation is used to develop its peripheral circuits. The chip supports USB Type and can control the lighting circuit through the APP on the mobile phone, so as to simulate the switch of household electrical appliances. In the future, consumers can purchase home appliances with built-in communication modules and integrate them with the Home Energy Management System (HEMS), which can be used to control wireless energy-saving.
V-band Flip-Chip pHEMT Balanced Power Amplifier with CPWG-MS-CPWG Topology and CPWG Lange Couplers
(2017-01-01)
Chang, Wei-Ling
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Su, Jen-Yi
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Meng, Chinchun
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Chang, Chia-Hung
;
Huang, Guo-Wei
A V-band balanced two-stage power amplifier MMICs with Lange couplers is demonstrated using 0.15 mu m GaAs pHEMT technology in this paper. A CPWG-MS-CPWG topology with via holes at the transistors as the transition between coplanar waveguide with backside ground (CPWG) and microstrip (MS) is employed for the two-stage amplifier. CPWG is applied to realize the flip-chip transition interface for both input and output ports of the amplifier and inter-stage MS matching has the advantage of small size. The structure parameters of the CPWG Lange coupler and matching network are designed and optimized for power combining. Finally, a 60-GHz balanced two-stage power amplifier using a CPWG-MS-CPWG structure delivers the small signal gain of 18 dB, OP1dB of 12 dBm and P-sat of 15 dBm.

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