21 results on '"Yonghyun Shim"'
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2. 29.2 A transmitter and receiver for 100Gb/s coherent networks with integrated 4×64GS/s 8b ADCs and DACs in 20nm CMOS.
- Author
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Jun Cao 0001, Delong Cui, Ali Nazemi, Tim He, Guansheng Li, Burak çatli, Mehdi Khanpour, Kangmin Hu, Tamer A. Ali 0001, Heng Zhang, Hairong Yu, Ben Rhew, Shiwei Sheng, Yonghyun Shim, Bo Zhang 0029, and Afshin Momtaz
- Published
- 2017
- Full Text
- View/download PDF
3. 29.2 A transmitter and receiver for 100Gb/s coherent networks with integrated 4×64GS/s 8b ADCs and DACs in 20nm CMOS
- Author
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Mehdi Khanpour, Shiwei Sheng, Afshin Momtaz, Delong Cui, Tim He, Ali Nazemi, Tamer Ali, Heng Zhang, Burak Catli, Ben Rhew, Yonghyun Shim, Jun Cao, Guansheng Li, Bo Zhang, Kangmin Hu, and Hairong Yu
- Subjects
Engineering ,business.industry ,020208 electrical & electronic engineering ,Transmitter ,020206 networking & telecommunications ,02 engineering and technology ,Phase-locked loop ,CMOS ,Transmission (telecommunications) ,Baud ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Transceiver ,business ,Digital signal processing ,Phase-shift keying - Abstract
At rates of 100Gb/s and above, CMOS DSP-based transceivers integrated with high-sampling-rate data converters are critical to realize the phase-sensitive modulation schemes based on coherent detection that are essential to metro and long-haul networks [1]. To support dual-polarization QPSK format, quad low-power DACs and ADCs are needed and precise phase alignment has to be maintained between XI, XQ, YI, and YQ channels, in order to transmit and extract the phase information in the coherent system, as shown in Fig. 29.2.1. For long-haul transmission at 100Gb/s, because of the FEC overhead, the baud rate per channel can be as high as 32Gb/s. In addition, the receiver often requires double sampling at 64GS/s for robust clock-data recovery and SNR improvement for stressed channels. Double sampling also enables the DSP to implement more complicated equalization schemes and more flexible spectrum engineering at high frequency on the transmitter side. This paper reports the receiver and transmitter fully integrated in a 100G coherent DSP chip, using 4×64GS/s ADCs and DACs with 8b resolution, fabricated in a standard 20nm CMOS process.
- Published
- 2017
4. Multi-modal Transit Station Planning Method Using Discrete Event System Formalism
- Author
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Changbeom Choi, Yonghyun Shim, Seonwha Baek, Jaewoong Choi, Onyu Kang, and Bitnal Kim
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Modeling and simulation ,Formalism (philosophy of mathematics) ,Crowds ,DEVS ,Modal ,Discrete event system ,Computer science ,Simulation modeling ,Real-time computing ,Complex system - Abstract
A multi-modal transit station is a complex system in the urban system and takes important roles in our daily life. Since various transportation systems a large scale of passenger participates to the station, design and analysis of the multi-modal transit station are important problem. This paper presents a modeling and simulation method to support designing the transit station. First, we introduce the modeling method to build a simulation models to capture the behavior of vehicles and the crowds using the Discrete Event System (DEVS) formalism. Then, we introduce a simulation environment for multi-modal transit station which is based on the DEVSim++. In this simulation environment, we support requirement verification method based on the untimed DEVS model, and it checks the requirements by executing the simulation model and the untimed DEVS model altogether.
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- 2016
5. A High-Performance Continuously Tunable MEMS Bandpass Filter at 1 GHz
- Author
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Zhengzheng Wu, Yonghyun Shim, and Mina Rais-Zadeh
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Radiation ,Materials science ,business.industry ,Low-pass filter ,Electrical engineering ,Condensed Matter Physics ,Band-pass filter ,Insertion loss ,Optoelectronics ,Prototype filter ,Electrical and Electronic Engineering ,Center frequency ,Mechanical filter ,business ,High-pass filter ,Active filter - Abstract
This paper reports a continuously tunable lumped bandpass filter implemented in a third-order coupled resonator configuration. The filter is fabricated on a Borosilicate glass substrate using a surface micromachining technology that offers hightunable passive components. Continuous electrostatic tuning is achieved using three tunable capacitor banks, each consisting of one continuously tunable capacitor and three switched capacitors with pull-in voltage of less than 40 V. The center frequency of the filter is tuned from 1 GHz down to 600 MHz while maintaining a 3-dB bandwidth of 13%-14% and insertion loss of less than 4 dB. The maximum group delay is less than 10 ns across the entire tuning range. The temperature stability of the center frequency from -50°C to 50°C is better than 2%. The measured tuning speed of the filter is better than 80 s, and the is better than 20 dBm, which are in good agreement with simulations. The filter occupies a small size of less than 1.5 cm × 1.1 cm. The implemented filter shows the highest performance amongst the fully integrated microelectromechanical systems filters operating at sub-gigahertz range.
- Published
- 2012
6. Miniaturized UWB Filters Integrated With Tunable Notch Filters Using a Silicon-Based Integrated Passive Device Technology
- Author
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Mina Rais-Zadeh, Yonghyun Shim, and Zhengzheng Wu
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Radiation ,Materials science ,business.industry ,Condensed Matter Physics ,Band-stop filter ,Inductor ,Die (integrated circuit) ,Band-pass filter ,Filter (video) ,Return loss ,Electronic engineering ,Optoelectronics ,Insertion loss ,Prototype filter ,Electrical and Electronic Engineering ,business - Abstract
This paper reports on the implementation of miniaturized ultra-wideband filters integrated with tunable notch filters using a silicon-based integrated passive device technology. An ultra-wideband bandpass filter is realized on a micromachined silicon substrate, showing an insertion loss of 1.1 dB, return loss of better than 15 dB, and attenuation of more than 30 dB at both lower and upper stop-bands, with a spurious-free response up to 40 GHz. The filter occupies only 2.9 mm 2.4 mm of die area. To address the in-band interference issues associated with ultra-wideband communication, very compact tunable notch filters are monolithically integrated with the bandpass filters. A two-pole tunable notch filter integrated with an ultra-wideband filter provides more than 20 dB rejection in the 5-6 GHz range to reject U-NII interferences, with a total footprint of 4.8 mm 2.9 mm. The power handling, linearity, and temperature stability of filters are characterized and presented in this paper.
- Published
- 2012
7. A Low-Loss Directly Heated Two-Port RF Phase Change Switch
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Muzhi Wang, Yonghyun Shim, and Mina Rais-Zadeh
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Microelectromechanical systems ,Fabrication ,Materials science ,business.industry ,Electrical engineering ,Port (circuit theory) ,Cutoff frequency ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,RF switch ,chemistry ,Low-power electronics ,Optoelectronics ,Insertion loss ,Electrical and Electronic Engineering ,business ,Germanium telluride - Abstract
In this letter, we report on the design, fabrication, and measured results of a directly heated phase change RF switch (or via) using germanium telluride in a four-terminal configuration. The switch is heated using a separate heater path combining the advantages of directly heated vias, such as low power dissipation for phase transition, and indirectly heated vias, such as high power handling capability. The phase change switch shows an insertion loss of less than 0.6 dB and an isolation of higher than 20 dB at frequencies up to 20 GHz, indicating a cutoff frequency of more than 3.7 THz. The switch area is only 4 μm× 6 μm, which is smaller than RF MEMS switches with similar insertion loss performance. To the best of our knowledge, this is the first report on a four-terminal, directly heated, RF phase change switch.
- Published
- 2014
8. Non-Linearity Analysis of RF Ohmic Switches Based on Phase Change Materials
- Author
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Mina Rais-Zadeh and Yonghyun Shim
- Subjects
Materials science ,business.industry ,Electrical engineering ,Phase-change material ,Electronic, Optical and Magnetic Materials ,Power (physics) ,Nonlinear system ,Electrical resistance and conductance ,Thermoelectric effect ,Radio frequency ,Electrical and Electronic Engineering ,business ,Joule heating ,Ohmic contact - Abstract
We report on a thermoelectric model that can be used to analyze the nonlinearity and power handling capability of RF switches based on phase change (PC) materials. To analyze the nonlinear behavior of the PC switches, the Poole-Frenkel effect, the variation of thermal and electrical conductance with temperature, and the effect of Joule heating with increased RF signal power are all taken into account. The simulated input third-order intercept point and the 1-dB compression point (P1dB) are compared with measured results of directly heated PC switches, showing a good agreement. Using this model, we provide insights into the effect of electrical resistance, and thermal properties, as well as the operation frequency on the switch nonlinearity and power handling capability.
- Published
- 2014
9. RF MEMS Passives on High-Resistivity Silicon Substrates
- Author
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Mina Rais-Zadeh, Yonghyun Shim, Jean-Pierre Raskin, and Cesar Roda Neve
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Microelectromechanical systems ,Frequency response ,Materials science ,Passivation ,Silicon ,business.industry ,Silicon dioxide ,chemistry.chemical_element ,Substrate (electronics) ,Condensed Matter Physics ,chemistry.chemical_compound ,chemistry ,Q factor ,Electronic engineering ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Layer (electronics) - Abstract
Diverse RF passive devices and microelectro- mechanical systems (MEMS) can be monolithically integrated on a high-resistivity silicon (HR-Si) substrate. However, parasitic surface conduction (PSC) at the interface of HR-Si and a silicon dioxide (SiO2) passivation layer reduces the effective substrate resistivity, which in turn results in deterioration of the device quality factor (Q) and non-linearity. Trap-rich HR-Si has been proposed as a low substrate loss alternative, eliminating the problems associated with PSC. However, the full potential of trap-rich HR-Si as a common platform for implementing MEMS passives is not fully explored. In this letter, we evaluate the effectiveness of the trap-rich layer by comparing the frequency response of a number of RF passive devices fabricated on standard and trap-rich HR-Si substrates. In addition, we suggest an electromagnetic (EM) simulation setup that can be used to efficiently and accurately simulate the device performance.
- Published
- 2013
10. Non-linear characteristics of passive elements on trap-rich high-resistivity Si substrates
- Author
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Mina Rais-Zadeh, C. Roda Neve, K. Ben Ali, Yonghyun Shim, and Jean-Pierre Raskin
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Total harmonic distortion ,Materials science ,Silicon ,business.industry ,Electrical engineering ,chemistry.chemical_element ,Substrate (electronics) ,Inductor ,Harmonic analysis ,chemistry ,Electrical resistivity and conductivity ,Optoelectronics ,Wafer ,Radio frequency ,business - Abstract
RF losses and non-linear behavior of RF passive elements such as coplanar transmission lines and inductors are analyzed. The investigated trap-rich HR-Si wafers with a fixed oxide layer of 150 nm-thick show true effective resistivity values higher than 4 kΩ-cm up to 5 GHz and harmonic distortion levels lower than −90 dBm for a 900 MHz input with signal level of +25 dBm. High quality factor of 60 is measured for a 2 nH inductor on a trap-rich HR-Si substrate at 2.73 GHz frequency of operation. Our investigations confirm the capability of trap-rich HR-SOI wafer for the integration of passive elements for RF systems.
- Published
- 2014
11. RF switches using phase change materials
- Author
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Yonghyun Shim, G. Hummel, and Mina Rais-Zadeh
- Subjects
Phase transition ,Materials science ,business.industry ,Orders of magnitude (temperature) ,Electrical engineering ,Return loss ,Insertion loss ,Optoelectronics ,business ,Capacitance ,Ohmic contact ,Amorphous solid ,Small form factor - Abstract
Phase change materials are attractive candidates for use in ohmic switches as they can be thermally transitioned between amorphous and crystalline states, showing several orders of magnitude change in resistivity. Phase change switches are fast, small form factor, and can be readily integrated with MEMS and CMOS electronics. As such, they have a great potential for implementing next-generation high-speed reconfigurable RF modules. In this paper, we report on the RF properties of germanium tellurium, a PC material, and its use in RF switching applications. Intrinsic resistance and capacitance at the ON (crystalline) and OFF (amorphous) states of a directly heated switch are compared and characterized. Other properties such as phase transition conditions, insertion loss, return loss, and power handling capability of the switch are also measured and analyzed.
- Published
- 2013
12. An integrated RF MEMS tunable filter
- Author
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Mina Rais-Zadeh, Zhengzheng Wu, Jia Ruan, and Yonghyun Shim
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Materials science ,Electronic filter topology ,Hardware_PERFORMANCEANDRELIABILITY ,Distributed element filter ,law.invention ,Capacitor ,Band-pass filter ,Hardware_GENERAL ,law ,Filter (video) ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Prototype filter ,Active filter ,Electronic filter - Abstract
This paper reports on a high-performance MEMS lumped bandpass filter continuously tuned from 1 GHz to 0.6 GHz using 12 electrostatically actuated MEMS capacitors. To demonstrate the benefits of MEMS technologies, a reconfigurable filter array is implemented on a PCB using SMT components and its performance is compared to that of the MEMS filter. Besides the advantage in size, the MEMS filter also exhibits lower loss and greater rejection. To become a viable solution for RF applications, other performance specifications of MEMS filters such as tuning speed and reliability need to be improved.
- Published
- 2012
13. Switchable wide tuning range bandstop filters for frequency-agile radios
- Author
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Mina Rais-Zadeh, Zhengzheng Wu, and Yonghyun Shim
- Subjects
Capacitor ,Surface micromachining ,Materials science ,law ,Electronic engineering ,Range (statistics) ,Prototype filter ,Stopband ,Ohmic contact ,Frequency agility ,law.invention - Abstract
This paper reports on micromachined tunable bandstop filters that exhibit an octave frequency tuning range with high stopband rejection and low out-of-band loss. In addition to continuous frequency tuning, stopband switch on-off capability is realized by employing ohmic switches along with tunable capacitors. The fully re-configurable filters in this work are fabricated using a silicon-based integrated passive device technology and are the smallest-size bandstop filters reported in the low SHF range.
- Published
- 2011
14. Miniaturized UWB bandpass filters integrated with notch filters using a Si-based integrated passive device technology
- Author
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Zhengzheng Wu, Yonghyun Shim, and Mina Rais-Zadeh
- Subjects
Materials science ,Silicon ,business.industry ,Attenuation ,Bandwidth (signal processing) ,chemistry.chemical_element ,Band-stop filter ,Band-pass filter ,chemistry ,Electronic engineering ,Optoelectronics ,Insertion loss ,Prototype filter ,business - Abstract
Summary form only given, as follows. Miniaturized UWB filters with low loss, steep rejection, and spurious-free response on a silicon substrate are reported. A UWB filter is demonstrated with less than 1 dB insertion loss, more than 30 dB stop-band rejection, occupying 2.9 mm × 2.4 mm of die area. A UWB filter with a notch filter is presented having a footprint of 4.6 mm × 2.9 mm. The notch filter centered at 5.285 GHz provides a maximum attenuation of 23 dB with 10 dB bandwidth of 7% and shows excellent temperature stability.
- Published
- 2011
15. Miniaturized UWB bandpass filters integrated with notch filters using a silicon-based integrated passive device technology
- Author
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Mina Rais-Zadeh, Zhengzheng Wu, and Yonghyun Shim
- Subjects
Materials science ,Silicon ,business.industry ,Attenuation ,Bandwidth (signal processing) ,chemistry.chemical_element ,Band-stop filter ,WiMAX ,Narrowband ,Band-pass filter ,chemistry ,Electronic engineering ,Optoelectronics ,Insertion loss ,business - Abstract
This paper reports on the implementation of miniaturized UWB filters with low loss, steep rejection, and spurious-free response on a silicon substrate. A UWB filter is demonstrated with an insertion loss of less than 1 dB, 3 dB bandwidth of 7.25 GHz, attenuation of more than 30 dB in both the lower (10 MHz–2.6 GHz) and the upper (12 GHz–20 GHz) stop-bands, occupying only 2.9 mm × 2.4 mm of die area. In addition, a novel design is proposed for the implementation of a narrowband notch filter, which can be integrated with UWB bandpass filters for rejecting strong in-band interferences. A UWB filter integrated with a notch filter is presented having a total footprint of 4.6 mm × 2.9 mm. The notch filter centered at 5.285 GHz provides a maximum attenuation of 23 dB with 10 dB fractional bandwidth of 7% to reject WLAN/WiMAX interferences. The temperature stability of the notch filter is better than 0.4 % in the temperature range of −30 °C to 70 °C.
- Published
- 2011
16. A high-performance, temperature-stable, continuously tuned MEMS capacitor
- Author
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Mina Rais-Zadeh, Yonghyun Shim, and Zhengzheng Wu
- Subjects
Microelectromechanical systems ,Self resonance frequency ,Materials science ,business.industry ,Hardware_PERFORMANCEANDRELIABILITY ,Atmospheric temperature range ,Temperature measurement ,Capacitance ,law.invention ,Stress (mechanics) ,Capacitor ,Quality (physics) ,Hardware_GENERAL ,law ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Optoelectronics ,business - Abstract
This paper reports on a continuously tunable MEMS capacitor with a wide tuning range of 5∶1, high quality factor of better than 100 (at 1 GHz) at each tuned state, and self-resonance frequency of more than 13.5 GHz. The temperature stability of the capacitance in the temperature range of −50 °C to 60 °C is better than 7%, which is one of the best reported for continuously tuned capacitors. The maximum tuning speed of the capacitor is measured to be better than 40 µsec.
- Published
- 2011
17. Q AMPLIFICATION IN GALLIUM NITRIDE THICKNESS-MODE FILTERS USING ACOUSTOELECTRIC EFFECT
- Author
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V. A. Thakar, Mina Rais-Zadeh, Yonghyun Shim, and Vikrant J. Gokhale
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,business.industry ,Mode (statistics) ,Optoelectronics ,Gallium nitride ,business - Published
- 2010
18. Observation of the acoustoelectric effect in gallium nitride micromechanical bulk acoustic filters
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Mina Rais-Zadeh, Yonghyun Shim, and Vikrant J. Gokhale
- Subjects
Acoustic filters ,Frequency response ,Materials science ,business.industry ,Acoustics ,Gallium nitride ,chemistry.chemical_compound ,Resonator ,Acoustic wave propagation ,chemistry ,Electric field ,Electrode ,Optoelectronics ,Insertion loss ,business - Abstract
We report on the experimental verification of the acoustoelectric effect in gallium nitride (GaN) and present a model to describe this effect in GaN thickness-mode bulk acoustic filters. Filters are fabricated using 2.2 µm thick n-type GaN on high resistivity silicon epiwafers obtained from SOITEC. Acoustoelectric effect was observed by applying an electric field parallel to c-axis, the direction of acoustic wave propagation. Improvement in the insertion loss and out-of-band rejection was observed and Q amplifications exceeding 240% was achieved. Acoustoelectric effect makes it possible to dynamically tune the frequency response of GaN resonators and filters.
- Published
- 2010
19. Low-loss MEMS band-pass filters with improved out-of-band rejection by exploiting inductive parasitics
- Author
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Roozbeh Tabrizian, Mina Rais-Zadeh, Farrokh Ayazi, and Yonghyun Shim
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Microelectromechanical systems ,Capacitor ,Materials science ,Band-pass filter ,law ,Attenuation ,Matched filter ,Electronic engineering ,Insertion loss ,Parasitic extraction ,Passband ,law.invention - Abstract
This paper reports on a new implementation of integrated lumped filters with improved out-of-band rejection and passband loss. Inductive parasitics are exploited to provide additional transmission zeros at the high frequency end, which can improve both the out-of-band rejection and roll-off. Thick silver is electroplated to reduce the insertion loss and achieve high quality factor. An insertion loss of better than 3dB has been achieved for filters across 220MHz to 640MHz with unloaded Q as high as 50. The out-of-band rejection of filters is as high as 60dB. These are believed to be the highest performing integrated filters in terms of out-of-band attenuation and spurious-free response implemented on silicon substrate.
- Published
- 2009
20. A high-performance, temperature-stable, continuously tuned MEMS capacitor.
- Author
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Yonghyun Shim, Zhengzheng Wu, and Rais-Zadeh, M.
- Published
- 2011
- Full Text
- View/download PDF
21. High Speed Data Converters and Their Applications in Optical Communication System
- Author
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Tim He, Ali Nazemi, Guansheng Li, Yonghyun Shim, Shiwei Sheng, Jun Cao, Ben Rhew, Delong Cui, Burak Catli, Heng Zhang, Bo Zhang, Kangmin Hu, and Afshin Momtaz
- Subjects
Computer science ,business.industry ,020208 electrical & electronic engineering ,Optical communication ,02 engineering and technology ,computer.file_format ,Data conversion ,QAM ,CMOS ,Pulse-amplitude modulation ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,business ,computer ,Digital signal processing ,Quadrature amplitude modulation ,Phase-shift keying - Abstract
The rapid growth of data center traffic, driven by cloud technology adoption, has propelled the development of a variety of spectrally efficient modulation formats, such as 4-level pulse amplitude modulation (PAM4), quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM). High speed CMOS DSP-based transceivers provide complex equalization scheme to compensate for the channel loss as well as the nonlinearity impairments introduced by chromatic and polarization dispersion. The recent development of ultra-high speed data converters has been a key enabling technology converting data signal between analog and digital domain, which has shaped the traditional communication transceiver systems. This paper covers the advancement of CMOS data converter technology and its wide application, as well as the future development and trend.
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