Han-Yu CHEN Kun-Ming CHEN Guo-Wei HUANG Chun-Yen CHANG
Direct parameter extraction is believed to be the most accurate method for equivalent-circuits modeling of heterojunction bipolar transistors (HBT's). Using this method, the parasitic elements, followed by the intrinsic elements, are determined analytically. Therefore, the quality of the extrinsic elements extraction plays an important role in the accuracy and robustness of the entire extraction algorithm. This study proposes a novel extraction method for the extrinsic elements, which have been proven to be strongly correlated with the intrinsic elements. By utilizing the specific correlation, the equivalent circuit modeling is reduced to an optimization problem of determining six specific extrinsic elements. Converting the intrinsic equivalent circuit into its common-collector configuration, all intrinsic circuit elements are extracted using exact closed-form equations for both the hybrid-π and the T-topology equivalent circuits. Additionally, a general explicit equation on the total extrinsic elements is derived, subsequently reducing the number of optimization variables. The modeling results are presented, showing that the proposed method can yield a good fit between the measured and calculated S parameters.
Sheng-Yu WEN Guo-Wei HUANG Kun-Ming CHEN
In this paper, an accurate and low-cost method for on-wafer noise figure measurement, specifically designed for low-noise amplifiers (LNAs), will be proposed. An experiment conducted on a 5 GHz LNA demonstrates that a good agreement can be reached between the measurement result of the proposed method and that of a commercial noise parameter measurement system.
Shih-Dao WU Guo-Wei HUANG Kun-Ming CHEN Hua-Chou TSENG Tsun-Lai HSU Chun-Yen CHANG
RF MOSFET's are usually measured in common source configuration by a 2-port network analyzer, and the common gate and common drain S-parameters cannot be directly measured from a conventional 2-port test structure. In this work, a 4-port test structure for on-wafer measurement of RF MOSFET's is proposed. Four-port measurements for RF MOSFET's in different dimensions and the de-embedded procedures are performed up to 20 GHz. The S-parameters of the RF MOSFET in common source (CS), common gate (CG), and common drain (CD) configurations are obtained from a single DUT and one measurement procedure. The dependence of common source S-parameters of the device on substrate bias are also shown.
Tzung-Han WU Chinchun MENG Tse-Hung WU Guo-Wei HUANG
This paper demonstrates a small compact 5.7 GHz upconversion Gilbert micromixer using 0.35 µm SiGe HBT technology. A micromixer has a broadband matched single-ended input port. A passive LC current combiner is used to convert micromixer differential output into a single-ended output and doubles the output current for single-ended-input and single-ended-output applications. Thus, a truly balanced operation of a Gilbert upconversion mixer with a single-ended input and a single-ended output is achieved in this paper. The fully matched upconversion micromixer has conversion gain of -4 dB, OP1 dB of -9 dBm and OIP3 of 4 dBm when input IF=0.3 GHz, LO=5.4 GHz and output RF=5.7 GHz. The IF input return loss is better than 18 dB for frequencies up to 20 GHz while RF output return loss is 25 dB at 5.7 GHz. The supply voltage is 3.3 V and the current consumption is 4.6 mA. The die size is 0.90.9 mm2 with 3 integrated on-chip inductors.
Shu-Yu JIANG Chan-Wei HUANG Yu-Lung LO Kuo-Hsing CHENG
Several problems in built-in-jitter-measurement (BIJM) system designs have been identified in recent years. The problems are associated with the external low-jitter sampling clock, chip area, timing resolution, or the measurement range via the process voltage temperature (PVT) variation effect. In this work, there are three proposed approaches and one conventioanl method that improve BIJM systems. For the system level, a proposed real equivalent-signal sampling technique is utilized to clear the requirement of the external low-jitter sampling clock. The proposed Vernier caliper structure is applied to reduce chip area cost for the designated timing resolution. At the circuit level, the proposed auto focus technique eliminates the PVT variation effect for the measurement range. The stepping scan technique is the conventional method that employed to minimize the area cost of counter circuits. All of these techniques were implemented in the 0.35 µm CMOS process. Furthermore, these techniques are successfully verified in 14 ps circuit resolution and a 500*750 µm chip area for the 100-400 MHz measurement range.
Chang RUAN Jianxin WANG Jiawei HUANG Wanchun JIANG
In data center networks, Quantized Congestion Notification (QCN) has been ratified as the standard congestion management mechanism in the link layer. Since QCN nonlinearly switches between the rate increase and decrease stages, it is very difficult to understand QCN in depth and provide theoretical guidelines on setting the buffer size of the QCN switch. This paper gives an explicit formula for the boundary of buffer occupancy of the QCN switch. Specifically, based on the fluid model of QCN, we first derive the uniformly asymptotic stability condition of the QCN system. Then, under the condition that QCN is uniformly asymptotically stable, we analyze the buffer occupancy of the QCN switch theoretically and show that the classic rule-of-thumb for buffer sizing is not suitable for QCN. Finally, simulations validate the accuracy of our theoretical results.
Wei HUANG Essam A. SOUROUR Masao NAKAGAWA
Microcellular radio direct-sequence code division multiple access (DC-CDMA) system using optical link to connect their base stations to a central station is a solution of cost-effective and efficient spectrum reuse to meet the growing demand for mobile communications. In addition to the inherent multiuser interference (MUI) of CDMA signals, the system capacity is significantly reduced by a nonlinear distortion (NLD) due to the nonlinearity of optical link. In this paper, a two-stage cancellation technique is introduced into the system to cancel both the MUI and the NLD. It is performed at the receiver of the central station where the random ingredients of all user signals are estimated, and the MUI and the NLD are rebuilt and removed from the received signal. The validity of the cancellation technique is theoretically analyzed and shown by the numerical results. The analytical method and its results are also applicable to other general nonlinear CDMA.
Kuei-Ann WEN Wen-Shen WUEN Guo-Wei HUANG Liang-Po CHEN Kuang-Yu CHEN Shen-Fong LIU Zhe-Sheng CHEN Chun-Yen CHANG
There is increasing interest using CMOS circuits for highly integrated high frequency wireless telecommunications systems. This paper reviews recent works in transceiver architectures, circuits and devices technology for CMOS RFIC application. A number of practical problems those must be resolved in CMOS RFIC design are also discussed.
Ming-Hsiang CHO Guo-Wei HUANG Chia-Sung CHIU Kun-Ming CHEN An-Sam PENG Yu-Min TENG
In this study, a cascade open-short-thru (COST) de-embedding procedure is proposed for the first time for on-wafer device characterization in the RF/microwave frequency regime. This technique utilizes the "open" and "short" dummy structures to de-embed the probe-pad parasitics of a device-under-test (DUT). Furthermore, to accurately estimate the input/output interconnect parasitics, including the resistive, inductive, capacitive, and conductive components, the "thru" dummy device has been characterized after probe-pad de-embedding. With the combination of transmission-line theory and cascade-configuration concept, this method can efficiently generate the scalable and repeatable interconnect parameters to completely eliminate the redundant parasitics of the active/passive DUTs of various device sizes and interconnect dimensions. Consequently, this method is very suitable for the on-wafer automatic measurement.
Han-Yu CHEN Guo-Wei HUANG Kun-Ming CHEN Chun-Yen CHANG
In this letter, a new computation method for the noise parameters of a linear noisy two-port network is introduced. A new error function, which considers noise figure and source admittance error simultaneously, is proposed to estimate the four noise parameters. The global optimization of the error function is searched directly by using a genetic algorithm.
Weitao JIAN Ming CAI Wei HUANG Shichang LI
Mobility as a Service (MaaS) is a smart mobility model that integrates mobility services to deliver transportation needs through a single interface, offering users flexible and personalizd mobility. This paper presents a structural approach for developing a MaaS system architecture under Autonomous Transportation Systems (ATS), which is a new transition from the Intelligent Transportation Systems (ITS) with emerging technologies. Five primary components, including system elements, user needs, services, functions, and technologies, are defined to represent the system architecture. Based on the components, we introduce three architecture elements: functional architecture, logical architecture and physical architecture. Furthermore, this paper presents an evaluation process, links the architecture elements during the process and develops a three-layer structure for system performance evaluation. The proposed MaaS system architecture design can help the administration make services planning and implement planned services in an organized way, and support further technical deployment of mobility services.
Han-Yu CHEN Kun-Ming CHEN Guo-Wei HUANG Chun-Yen CHANG Tiao-Yuan HUANG
In this work, a simple method for extracting MOSFET threshold voltage, effective channel length and channel mobility by using S-parameter measurement is presented. In the new method, the dependence between the channel conductivity and applied gate voltage of the MOSFET device is cleverly utilized to extract the threshold voltage, while biasing the drain node of the device at zero voltage during measurement. Moreover, the effective channel length and channel mobility can also be obtained with the same measurement. Furthermore, all the physical parameters can be extracted directly on the modeling devices without relying on specifically designed test devices. Most important of all, only one S-parameter measurement is required for each device under test (DUT), making the proposed extraction method promising for automatic measurement applications.
The intermodulation distortion (IMD) due to laser diode (LD) nonlinearity of an asynchronous direct-sequence code division multiple access (DS/CDMA) system in optical transmission is analyzed. A third-order polynomial without memory is used to present LD nonlinearity. In DS/CDMA systems, only one harmonic of the third-order inter-modulation term falls on the signal frequency band and influences the system performance. The average distortion is derived with only the information of autocorrelation functions. The results are useful for CDMA system design and performance analysis. With LD nonlinearity it is necessary to select an optimal modulation index that provides a maximum signal-to-noise ratio (SNR). The analytical method is applicable to other general nonlinearities in CDMA systems.
Xue LEI Wei HUANG Wenqing FAN Yixian YANG
Dynamic analysis is frail and insufficient to find hidden paths in environment-intensive program. By analyzing a broad spectrum of different concolic testing systems, we conclude that a number of them cannot handle programs that interact with the environment or require a complete working model. This paper addresses this problem by automatically identifying and modifying outputs of the data input interface function(DIIF). The approach is based on fine-grained taint analysis for detecting and updating the data that interacts with the environment to generate a new set of inputs to execute hidden paths. Moreover, we developed a prototype and conducted extensive experiments using a set of complex and environmentally intensive programs. Finally, the result demonstrates that our approach could identify the DIIF precisely and discover hidden path obviously.
Wei HUANG Jiro TAKAYANAGI Tetsuo SAKANAKA Masao NAKAGAWA
Atmospheric optical communication (AOC) system using subcarrier PSK modulation is proposed and its superiority to OOK modulation in the presence of scintillation is discussed theoretically. An experimental AOC setup with a subcarrier modulated by 155.52(Mb/s) DPSK at light wave-length λ=0.83(µm) over an 1.8(km) outdoor path is employed to show the performance. Theoretical and experimental results are compared under scintillation in clear weather and a good agreement is observed. Finally, AOC systems using subcarrier M-ary PSK and multiple subcarriers are proposed and discussed.
An integrated slider-suspension system was designed and prototyped. The structure of this system has a full flying air-bearing surface in the leading part with a contamination-resistant feature, and it accommodates a slider with a 5-15 nm head-disk spacing at the trailing part. Performance analysis and simulation were conducted to validate the high performances of the design. Two key issues, the rigid motions (vibrations) and the elastic motions of the slider, were investigated systematically. For the rigid motions, it was found that the natural frequencies of the slider system are dependent on the disk contact stiffness and that the slider vibrations under excitation exhibit various nonlinear resonance. For the elastic motions, the average elastic response of the slider body under the random interaction of the interface was derived and characterized.
The effect of surface roughness is crucial for contact recording and proximity recording. In this paper a probability model is developed for investigation of the influence of surface roughness on flying performance and the contact force of the slider. Simulations are conducted for both the contact recording slider and the proximity recording slider, and the results are well coordinated with the reported experimental results and the self-conducted experimental results. Studies are further extended to the characterization of the roughness of the air bearing surface and the disk surface that may support head/disk spacing between 5 nm and 15 nm.
Load/unload techniques are widely used in mobile hard disk drives which have to endure external shocks frequently. ABS designs must consider both the load/unload performance and the shock resistance performance. Three ABS designs with different positions of the suction force center are studied in simulation. It is observed that when the position of the suction force center moves frontward, the anti-shock performance improves, but the unload performance degrades, and vice versa. A slider is not necessary to be designed to have its suction force center significantly behind of its geometric center, as the traditional load/unload sliders do. Instead, the suction force center can be designed near the geometric center if the hook limiter is used.
Sheng-Lyang JANG Chia-Wei CHANG Yu-Sheng CHEN Jhin-Fang HUANG Jau-Wei HSIEH Chong-Wei HUANG
A novel divide-by-3 injection-locked frequency divider (ILFD) is proposed. The ILFD circuit is realized with a cross-coupled n-core MOS LC-tank oscillator embedded with a push-push signal generator and two injection MOSFETs for coupling the injection signal into the resonator. The ILFD uses the linear mixer to extend the locking range and has been implemented in a standard 0.18 µm CMOS process. The core power consumption of the ILFD core is 3.12 mW. The divider's free-running frequency is tunable from 4.26 GHz to 4.9 GHz by tuning the varactor's control bias, and at the incident power of 0 dBm the locking range of the ILFD used as a divide-by-3 divider is 1.5 GHz, from 12.5 GHz to 14.0 GHz.
Tzung-Han WU Chinchun MENG Tse-Hung WU Guo-Wei HUANG
A 5.2 GHz 1 dB conversion gain, IP1 dB = -19 dBm and IIP3= -9 dBm double quadrature Gilbert downconversion mixer with polyphase filters is demonstrated by using 0.35 µm SiGe HBT technology. The image rejection ratio is better than 47 dB when LO=5.17 GHz and IF is in the range of 15 MHz to 45 MHz. The Gilbert downconverter has four-stage RC-CR IF polyphase filters for the image rejection. Polyphase filters are also used to generate LO and RF quadrature signals around 5 GHz in the double quadrature downconverter.