Browsing by Author "Chang, Chin-Wei"

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A Reconfigurable, Pulse-shaping Potentiometric Readout System for Bio-Sensing Transistors
(2019-01-01)
Lu, Shao-Yung
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Shan, Siang-Sin
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Yang, Jiancheng
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Chang, Chin-Wei
;
Ren, Fan
This paper presents a new multi-modality readout system for potentiometric electrochemical sensors. The design adopts a pulse modulation at the gate and drain of the Bio-FET sensors to reduce the effects of charge accumulation between the surface of the electrodes and the ion analytes. The adjustable duration and amplitude of stimuli signals provide flexibility for different biosensing applications and a wide range of detectable concentration. Also, an oscillator-based architecture is proposed for digitization and integration. The counting time can be adjusted to enhance the resolution of the readout system. The proposed potentiometric sensing system was tested with 0.1-10 mM Potassium Ferricyanide (K-3[Fe(CN)(6)]), and the results are interpreted in the micro-LCD on the board. The design offers the opportunity for a handheld medical device with fast and real-time monitoring of biomarkers and ion analytes.
Comprehensive Study of Pi-Gate Nanowires Poly-Si TFT Nonvolatile Memory With an HfO(2) Charge Trapping Layer
(2011-03-01)
Chen, Lun-Jyun
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Wu, Yung-Chun
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Chiang, Ji-Hong
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Hung, Min-Feng
;
Chang, Chin-Wei
This work demonstrates the feasibility of a polycrystalline silicon thin-film transistor (poly-Si TFTs) nonvolatile memory (NVM) that utilizes a Pi-shaped gate (Pi-gate) and multiple nanowire channels with a HfO(2) charge-trapping layer. The TFT NVM with the Pi-gate nanowires (NWs) structure has a higher program/erase (P/E) efficiency than that of the conventional single-channel TFT NVM; the memory window can achieve 2.3 V, only needs a programming time of 1 mu s. This high P/E efficiency follows from the improved gate control of the Pi-gate structure. A Pigate NWs poly-Si TFT NVM with a Si(3)N(4) charge-trapping layer was also fabricated. Since HfO(2) has a deeper conduction band than Si(3)N(4), the device with the HfO(2) charge-trapping layer has a higher programming efficiency and the better retention characteristics than that with the Si(3)N(4) charge-trapping layer. Additionally, the high programming efficiency allows the device with the HfO(2) charge-trapping layer to undergo more P/E cycles than that with the Si(3)N(4) charge-trapping layer.
Comprehensive Study of Pi-Gate Nanowires Poly-Si TFT Nonvolatile Memory With an HfO2 Charge Trapping Layer
(2011-03-01)
Chen, Lun-Jyun
;
Wu, Yung-Chun
;
Chiang, Ji-Hong
;
Hung, Min-Feng
;
Chang, Chin-Wei
This work demonstrates the feasibility of a polycrystalline silicon thin-film transistor (poly-Si TFTs) nonvolatile memory (NVM) that utilizes a Pi-shaped gate (Pi-gate) and multiple nanowire channels with a HfO2 charge-trapping layer. The TFT NVM with the Pi-gate nanowires (NWs) structure has a higher program/erase (P/E) efficiency than that of the conventional single-channel TFT NVM; the memory window can achieve 2.3 V, only needs a programming time of 1 mu s. This high P/E efficiency follows from the improved gate control of the Pi-gate structure. A Pigate NWs poly-Si TFT NVM with a Si3N4 charge-trapping layer was also fabricated. Since HfO2 has a deeper conduction band than Si3N4, the device with the HfO2 charge-trapping layer has a higher programming efficiency and the better retention characteristics than that with the Si3N4 charge-trapping layer. Additionally, the high programming efficiency allows the device with the HfO2 charge-trapping layer to undergo more P/E cycles than that with the Si3N4 charge-trapping layer.
DC and dynamic switching characteristics of field-plated vertical geometry beta-Ga2O3 rectifiers
(2019-01-01)
Yang, Jiancheng
;
Carey, Patrick
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Ren, Fan
;
Chen, Yen-Ting
;
Liao, Y.
Reverse breakdown voltages larger than 1 kV have been reported for both unterminated Ga2O3 vertical rectifiers (1000-1600 V) and field-plated Schottky diodes (1076-2300 V) with an epi thickness of 8-20 mu m. If the doping is in the 10(16) cm range, the breakdown is usually in the 500-800V regime. Furthermore, the switching characteristics of discrete Ga2O3 vertical Schottky rectifiers exhibited reverse recovery times in the range of 20 to 30 ns. Large area (up to 0.2 cm(2)) Ga2O3 rectifiers were fabricated on a Si-doped n-Ga2O3 drift layer grown by halide vapor phase epitaxy on a Sn-doped n(+) Ga2O3 (001) substrate. A forward current of 2.2 A was achieved in single-sweep voltage mode, a record for Ga2O3 rectifiers. The on-state resistance was 0.26 Omega.cm(2) for these largest diodes, decreasing to 5.9 x 10 Omega.cm(2) for 40x40 mu m devices. We detail the design and fabrication of these devices. In addition, an inductive load test circuit was used to measure the switching performance of field-plated, edge-terminated Schottky rectifiers with a reverse breakdown voltage of 760 V (0.1 cm diameter, 7.85 x10(-3) cm(2) area) and an absolute forward current of 1 A on 8 mu m thick epitaxial beta-Ga2O3 drift layers. These devices were switched from 0.225 A to -700 V with t of 82 ns, and from 1 A to -300 V with t of 64 ns and no significant temperature dependence up to 125 degrees C. There was no significant temperature dependence of t(rr)up to 150 degrees C.
Design of dual-band microstrip rat race coupler with circuit miniaturization
(2007)
Hsu, Ching-Luh
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Chang, Chin-Wei
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Kuo, Jen-Tsai
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電信工程研究所
;
Institute of Communications Engineering
Rat race ring coupler with stepped-impedance sections is designed to have a dual-band characteristic. This is realized by attaching open stubs to both ends of each stepped-impedance section to create a phase of 90 degrees at two designated frequencies. Transcendental equations are derived for solving impedance ratio R and lengths of the stepped-impedance sections. Circuit with miniaturized area can be obtained if R > 1. is chosen. Such microstrip ring hybrids operating at 2.45/5.2 GHz with R = 1 and R = 4 are designed and fabricated. Experiments are performed to confirm the theory.
Dynamic Switching Characteristics of 1 A Forward Current beta-Ga2O3 Rectifiers
(2019-01-01)
Yang, Jiancheng
;
Ren, Fan
;
Chen, Yen-Ting
;
Liao, Yu-Te
;
Chang, Chin-Wei
An inductive load test circuit was used to measure the switching performance of field-plated edge-terminated Schottky rectifiers with a reverse breakdown voltage of 760 V (0.1 cm diameter, 7.85 x 10(-3) cm(2) area) and an absolute forward current of 1 A on 8 mu m thick epitaxial beta-Ga2O3 drift layers. The recovery characteristics for these vertical geometry beta-Ga2O3 Schottky rectifiers switching from forward current of 1 A to reverse off-state voltage of -300 V showed a recovery time (trr) of 64 ns. There was no significant temperature dependence of trr up to 150 degrees C.
Implementation of a 900 V Switching Circuit for High Breakdown Voltage beta-Ga2O3 Schottky Diodes
(2019-05-22)
Chen, Yen-Ting
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Yang, Jiancheng
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Ren, Fan
;
Chang, Chin-Wei
;
Lin, Jenshan
This paper presents a switching circuit for high breakdown-voltage Ga2O3 vertical Schottky rectifiers. Field-plated edge-terminated (FPET) vertical Schottky diodes were fabricated on a 20-mu m thick Si-doped n-type Ga2O3 drift layer which was grown on the 650-mu m thick beta-Ga2O3 substrate via halide vapor phase epitaxy (HVPE). The measured reverse recovery time of the proposed Ga2O3 Schottky diode was 81 ns when switched to a reverse bias voltage of -900 V. The implementation of a switching circuit with the novel Ga2O3 diode is the first demonstrated at such a high switching voltage. This paper also provides insights for the practical implementation of the Ga2O3 vertical Schottky rectifiers from device fabrication to circuit design. (C) The Author(s) 2019. Published by ECS.
Miniaturized Dual-Band Hybrid Couplers With Arbitrary Power Division Ratios
(2009-01-01)
Hsu, Ching-Luh
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Kuo, Jen-Tsai
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Chang, Chin-Wei
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電信工程研究所
;
Institute of Communications Engineering
Branch-line and rat-race couplers are designed to have dual-band operation with arbitrary power division ratios. An elementary two-port is proposed to imitate the 90 degrees section at the two designated frequencies with different characteristic impedances. The two-port consists of a stepped-impedance section with open stubs attached to its two ends, and its circuit parameters are determined by the transmission line theory. The use of the stepped-impedance sections also leads to circuit miniaturization. By the standard microstrip technology., investigated also includes the realizable power division ratios and circuit bandwidths in the two bands, the upper limit of the ratio of the two designated frequencies and the miniaturization factor of the proposed circuit. Hybrid couplers operating at 2.45/5.2 GHz with various power division ratios are designed, fabricated and tested. Experiment results are compared with the theory and simulation.
Review-Opportunities for Rapid, Sensitive Detection of Troponin and Cerebral Spinal Fluid Using Semiconductor Sensors
(2019-11-20)
Carey, Patrick H.
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Lobo, Brian C.
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Gebhard, Michael P.
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Leon, Marino E.
;
Flax, Sherri D.
There are opportunities for development of modularized, inexpensive protein biomarker sensors in clinical applications. In this review we focus on two of these, namely early diagnosis of acute myocardial infarction (AMI) and detection of cerebral spinal fluid (CSF). Evaluation of patients with acute chest pain is challenging due to the heterogeneity of the underlying conditions, leading to patients with AMI being mistakenly sent home from emergency rooms or those at low risk for an adverse cardiac event being unnecessarily admitted without precise cardiac biomarker testing. Cardiac troponin I (cTnI) in cardiac muscle tissue is a standard clinical biomarker for AMI, as its concentration rises quickly in the blood during release from myocardial cells following cell death. The time-dependence of the cTnI concentration is the basis of antigen-antibody methodologies such as radioimmunoassay and enzyme-linked immunosorbent assay (ELISA). These methods are time consuming, leading to delays in diagnosis and higher costs. The challenge is to develop a real-time, accurate, low-cost point-of-care heart attack sensor. The coefficient of variation must be precise, within the parameters established by the American College of Cardiology. Similarly, leakage of cerebrospinal fluid (CSF) is a critical condition with a high risk of meningitis and potential mortality. The primary methods of detection for the biomarker beta 2-Transfferin (B2T) are immunofixation electrophoresis (IFE) and ELISA. Consistent IFE results down to 2 mu g/mL can be obtained in patient samples, but requires a minimum 2.5-hour testing period, which is not expedient for real time feedback during surgery in or around the central nervous system. Additionally, to achieve good sensitivity and handle the inherently low concentration of B2T in CSF, lab procedures require samples to be concentrated or run in duplicate to ensure accurate detection. Real time turnaround is on the order of days. To alleviate the slow turn-around times, there is strong interest in electronic detection methods for proteins using biologically functionalized transistors, which provide an electronic readout and are readily integrated with wireless data transmission. (C) The Author(s) 2019. Published by ECS.
Switching Behavior and Forward Bias Degradation of 700V, 0.2A, beta-Ga2O3 Vertical Geometry Rectifiers
(2019-01-30)
Yang, Jiancheng
;
Fares, Chaker
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Ren, Fan
;
Chen, Yen-Ting
;
Liao, Yu-Te
We report the switching recovery characteristics of large area (contact dimension 0.04 x 0.04 cm(2)) vertical geometry beta-Ga2O3 Schottky rectifiers, consisting of Si-doped epitaxial layers on conducting bulk substrates. Devices that were switched from forward current of 0.225 A to reverse off-state voltage of -700 V in an inductive load test circuit showed a recovery time (t(rr)) of 82 ns, with a reverse recovery current (I-rr) of 38 mA and dI/dt of -2.28 A. mu sec(-1). This shows the potential of Ga2O3 rectifiers for power switching applications, provided effective thermal management schemes can be implemented. Devices deliberately tested to failure under forward bias conditions exhibit delamination and cracking of the Ni/Au contact and underlying epitaxial Ga2O3 due to the low thermal conductivity of the Ga2O3. This failure mode is different to that under high reverse breakdown conditions, where pits formed by material failure under the high field generated at the edge of the rectifying contact occurs. (C) The Author(s) 2019. Published by ECS.
VEHICLE DETECTION IN THERMAL IMAGES USING DEEP NEURAL NETWORK
(2018-01-01)
Chang, Chin-Wei
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Srinivasan, Kathiravan
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Chen, Yung-Yao
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Cheng, Wen-Huang
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Hua, Kai-Lung
In today's world, it becomes critical for a self-driving car to detect the vehicles irrespective of it being a day or night. We propose a real-time vehicle detection using a sequence of night-time thermal images. Moreover, the thermal images have the capability of retaining even the minuscule vehicle details in a dim environment. For an efficient vehicle detection, the thermal image dataset collected during the dusk and night is used for training purposes. Subsequently, the contrast enhancement and sharpening of these images are performed using the Thermal Feature Enhancement (TFE). Then the concatenated images are supplied as the input to allow the model to learn more effectively. Besides, we also propose an improved convolution network model entitled as the Thermal Image Only Looked Once (TOLO) model for vehicle detection. Additionally, we propose a method called as Low Probability Candidate Filter (LPCF) to compensate the probability of not-easy-to-detect vehicles. Our proposed method produces better results for the F1-measure in comparison with existing methods.