Browsing by Author "Lin, Jenshan"

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A reconfigurable filter based on doublet configuration
(2007)
Liao, Ching-Ku
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Chang, Chi-Yang
;
Lin, Jenshan
;
電信工程研究所
;
Institute of Communications Engineering
A surrogate model is proposed to model a previously published second-order tunable filter. The surrogate model can be represented by a coupling matrix in a doublet configuration, and a simple method based on the even-odd mode bisection is given to extract the coupling matrix. From the extracted parameters, one can decide how to design a filter with prescribed quasi-elliptic responses and how to adjust varactors to reconfigure the response. Using the proposed methods, the second-order filter can be configured to have a finite transmission zero on either the lower side or the upper side of the passband in a prescribed location even when the center frequency of the filter is tuned. Both simulated and measured results of an example are presented.
A Reconfigurable, Pulse-shaping Potentiometric Readout System for Bio-Sensing Transistors
(2019-01-01)
Lu, Shao-Yung
;
Shan, Siang-Sin
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Yang, Jiancheng
;
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.
A software configurable coupler with programmable coupling coefficient
(2007)
Wang, Shih-Ming
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Chang, Chi-Yang
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Lin, Jenshan
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電信工程研究所
;
Institute of Communications Engineering
A novel microstrip parallel coupler with tunable coupling coefficient is proposed. Two varactors are placed on microstrip parallel-coupled lines to tune the coupling coefficient. With proper combinations of the capacitances of two varactors, the coupling coefficient can be tuned from 10 dB to 6 dB with good return loss and directivity. By using the Labview program and data acquisition component, at software configurable coupler is implemented. This software configurable coupler will be useful in microwave instrumentation.
A vector-fitting formulation for parameter extraction of lossy microwave filters
(2007-04-01)
Liao, Ching-Ku
;
Chang, Chi-Yang
;
Lin, Jenshan
;
電信工程研究所
;
Institute of Communications Engineering
In this letter, a formulation based on the vector fitting is applied to extract the equivalent circuit model from the frequency response of lossy cross-coupled microwave filters. By approximating the lossy response with short-circuit admittance parameters in partial fractional expansion form, the proposed method can evaluate the unloaded quality factor of resonators and extract the transversal coupling matrix simultaneously. The methodology of the vector fitting can identify the poles and residues of the short-circuit admittance parameters even when the poles are on the complex plane. And the extracted transversal coupling matrix can further transform into the prescribed form corresponding to the physical layout. The proposed method can be used in the tuning process of filter designs where the extraction of a coupling matrix is essential. To verify the method, a cross-coupled quadruplet filter is used as an example.
DC and dynamic switching characteristics of field-plated vertical geometry beta-Ga2O3 rectifiers
(2019-01-01)
Yang, Jiancheng
;
Carey, Patrick
;
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.
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
;
Yang, Jiancheng
;
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.
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
;
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.