The transitions between rectangular and circular waveguides are very useful components especially for some complicated microwave systems. In general, trial and error methods are used to design these types of transitions. Some numerical... more
The transitions between rectangular and circular waveguides are very useful components especially for some complicated microwave systems. In general, trial and error methods are used to design these types of transitions. Some numerical techniques in frequency domain have previously been applied to waveguide transition structures, but the procedure is cumbersome and depends on expensive analytical calculations. The FDTD is claimed to be a versatile technique for analysis of passive microwave structures. The purpose of the paper is to confirm this claim by applying FDTD to several complex waveguide transitions which are not amiable to many frequency domain techniques such as the mode matching method. It is demonstrated that this algorithm is versatile and can be used to analyze complicated waveguide transitions with a high degree of accuracy. Analysis of such structures can be quite complicated in the frequency domain. For example, the plane wave functions are used to represent the fields inside a rectangular waveguide, while the cylindrical wave functions are used for the cylindrical waveguide. As a result, the frequency domain analysis of a rectangular to circular waveguide transition requires careful considerations for proper numerical convergence. Such a problem is successfully analyzed in the time domain by application of the FDTD algorithm to the structure geometry.
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Based on the idea of distributed amplifier, a wideband active power divider is designed using 90 nm CMOS process to provide positive gain and superb isolation between its two output ports from quasi-DC up to 40 GHz. Compared with our... more
Based on the idea of distributed amplifier, a wideband active power divider is designed using 90 nm CMOS process to provide positive gain and superb isolation between its two output ports from quasi-DC up to 40 GHz. Compared with our previously demonstrated 20GHz one, the requirement of good input matching over the whole bandwidth poses an even severe constraint in the development of this 40GHz active power splitter, as the tradeoff between gain and bandwidth becomes more intricate now. Mutual-coupling inductors are therefore adopted in the circuit’s artificial transmission line to improve both the input return loss and allow the use of larger transistors in the gain stage. The fabricated circuit exhibits good input and output matching and has better than 10 dB output-port isolation across the whole band, with the bias of 1.8V and 190 mA. Related circuit theories and mathematics will also be presented in this paper.
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A novel decade bandwidth resistive FET singly balanced MIC mixer using a broadband CPW to CPS balun is developed. The mixer uses two NEC71000 MESFETs and realized with uniplanar lines. At 17 dBm LO power and 1 GHz IF, the mixer shows a... more
A novel decade bandwidth resistive FET singly balanced MIC mixer using a broadband CPW to CPS balun is developed. The mixer uses two NEC71000 MESFETs and realized with uniplanar lines. At 17 dBm LO power and 1 GHz IF, the mixer shows a conversion loss of 5.7 to 11 dB for 2 to 20 GHz RF and 10 to 15
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We report on the design of a temperature-compensated power amplifier module which can generate 20Watt output power with 34dB gain at 14GHz. This module is made of one commercial microwave monolithic integrated circuit and three discrete... more
We report on the design of a temperature-compensated power amplifier module which can generate 20Watt output power with 34dB gain at 14GHz. This module is made of one commercial microwave monolithic integrated circuit and three discrete power transistors. Allowing gate biases of these power transistors to be automatically adjusted with ambient temperature, output power of the module can now be more steadily reaching stabilization. Details regarding the microwave power amplifier and the DC biasing circuit will be presented in this paper.
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Su/mmary form only given. Power dividers have been extensively used in many microwave circuits and sub-systems such as feeding networks for antenna arrays and power amplifiers. For applications requiring high power-handling capability and... more
Su/mmary form only given. Power dividers have been extensively used in many microwave circuits and sub-systems such as feeding networks for antenna arrays and power amplifiers. For applications requiring high power-handling capability and low insertion loss, conventional E- and H-plane waveguide T-junctions would be the simplest three-port designs. However, due to their lossless nature and reciprocal property, such junctions cannot be matched simultaneously at all ports. In addition, poor isolation exists between their output ports. These problems place severe limitation on their practical applications. Bifurcated waveguide power dividers were proposed to solve the aforementioned problems. The early bifurcation design features a thin metallic plate inside a rectangular waveguide. The plate is positioned perpendicular to the TE10 electric field, which is known as an E-plane bifurcation and is able to effectively convert the guide into two reduced-height waveguides. This design offers a solution to determine the power ratio of two output ports by taking the quotient of the two reduced heights of the bifurcated waveguide, but still fails to improve the isolation between the output ports. The introduction of a resistive coupling slot in the thin metallic plate was presented to solve the isolation problem (F. Takeda, O. Ishida, and Y. Isoda, IEEE MTT-S Digest, 1982.) The resistive coupling slot consists of a transverse slot and a small resistor. The isolation between two output ports was increased up to at least 30 dB within a 10% frequency range of interest. For millimeter-wave applications, implementation of such resistive coupling slot presents difficulty if the cost and ease of fabrication need to be considered. Therefore, a resistive film was proposed to replace the thin metallic plate with a resistive coupling slot. Current resistive films are made of tantalum nitride (TaN) and must stay on a supportive object. They are usually available in two resistive values, 50 Ω/sq and 200 Ω/sq. The length and width of the resistive film must be adjusted to achieve the desired resistance. In this study, a properly-sized resistive film of 75 Ω sandwiched by two alumina substrates is proposed to serve as a septum for the bifurcated waveguide. Impedance transformation can be implemented at either the input port or the two output ports for three-port power dividers. A corporate configuration is chosen for designs with 2n output ports (n > 1). Design examples for three-port and five-port bifurcated waveguide power dividers at Ka-band are presented. The finite element method-based commercial CAD package - HFSS was chosen to conduct the required simulations because of its accuracy for designs involving 3-D structures. The simulation results indicate that the insertion loss is maintained to be less than 3.1 dB for the three-port design and 6.1 dB for the five-port design across the frequency range of interest. The return loss and the isolation are more than 20 dB for both designs. The results are verified with measured data and good agreement is observed.
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Two kind of balun transformers are composed of a balun transition and an impedance matching circuit. Both of them have good performance and compact size. Chemical etching compatible with the common microwave circuit manufacturing process... more
Two kind of balun transformers are composed of a balun transition and an impedance matching circuit. Both of them have good performance and compact size. Chemical etching compatible with the common microwave circuit manufacturing process is employed to make them. Using the odd-mode analysis and commercial microwave software to design the balun transformer, it is more accurate and more efficient
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This manuscript describes our W-band LNA design using commercial 90nm CMOS process. For effectively extending the amplifier's bandwidth without compromising its wideband matching or noise figure, a combination of common-source and... more
This manuscript describes our W-band LNA design using commercial 90nm CMOS process. For effectively extending the amplifier's bandwidth without compromising its wideband matching or noise figure, a combination of common-source and cascode gain stages are employed for the five-stage circuit design. This 1200×900μm2 low-noise amplifier has more than 10dB gain and around 12dB noise figure, with 41mW power consumption. Though primarily developed for our receiver array, this W-band LNA does find applications in areas such as image sensing, surveillance, radar, and millimeter-wave instrumentations. With consistent simulated and measured results, this circuit can be modified for covering even wider bandwidth whenever needed.
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This paper describes a broadband 10-110 GHz mm-wave rat-race ring diode mixer. The mixer can be used as a fundamental mixer as well as a harmonic mixer. The finite- ground-width CPW on a 15 mil alumina substrate is used to implement the... more
This paper describes a broadband 10-110 GHz mm-wave rat-race ring diode mixer. The mixer can be used as a fundamental mixer as well as a harmonic mixer. The finite- ground-width CPW on a 15 mil alumina substrate is used to implement the circuit. The mixer is designed to allow DC bias that a local power as low as 0 dBm could properly pump the mixer. Two commercial available M/A-Com MA4E2037 GaAs beam-leaded Schottky diodes are used. The measured conversion loss is typically 9 dB from 10 to 100 GHz in the fundamental mixing mode and 15 dB from 20 to 110 GHz in the harmonic mixing mode.
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In this paper, a high-gain and wideband low-noise amplifier using 65-nm CMOS process is proposed. A four-stage cascode configuration is adopted to achieve the high gain and wideband performance. With 24-mA dc current and 2-V supply... more
In this paper, a high-gain and wideband low-noise amplifier using 65-nm CMOS process is proposed. A four-stage cascode configuration is adopted to achieve the high gain and wideband performance. With 24-mA dc current and 2-V supply voltage, the LNA not only provides gain higher than 20 dB from 75.5 GHz to 120.5 GHz, but also has a measured noise figure between 6 and 8.3 dB from 87 to 100 GHz. The output 1-dB compression power (OP1dB) is −3 dBm at 110 GHz, and the chip size is 0.55 × 0.45 mm2.
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In this paper, we present an E-band MMIC low noise amplifier (LNA) using 0.1-μm GaAs pHEMT technology operating in 1V and 2V drain voltage. The E-band LNA shows small signal gain of 28 dB from 62 to 77 GHz with DC power consumption 44 mW.... more
In this paper, we present an E-band MMIC low noise amplifier (LNA) using 0.1-μm GaAs pHEMT technology operating in 1V and 2V drain voltage. The E-band LNA shows small signal gain of 28 dB from 62 to 77 GHz with DC power consumption 44 mW. Noise measurement conducts in the package shows average noise figure about 4.5 dB from 75 to 90 GHz. The figure-of-merit (FOM) is 212.5 (GHz/mW), which is highest compared with other LNAs using 0.1-μm GaAs pHEMT technology.
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A 60GHz SiGe HBT transmitter IC with integrated antenna in a standard-bulk 0.18mum SiGe BiCMOS process is reported. This chip is composed of a VCO, a sub-harmonic mixer, a PA, and a tapered-slot antenna, all with differential designs. The... more
A 60GHz SiGe HBT transmitter IC with integrated antenna in a standard-bulk 0.18mum SiGe BiCMOS process is reported. This chip is composed of a VCO, a sub-harmonic mixer, a PA, and a tapered-slot antenna, all with differential designs. The measured results show 15.8dBm output power and 20.2dB conversion gain with 281mWdc power consumption
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The function of power divider is to divide to power from one input port into the divided power at multiple output ports, or to combine the power from multiple ports into the combined power at one output port. The goal of this study is to... more
The function of power divider is to divide to power from one input port into the divided power at multiple output ports, or to combine the power from multiple ports into the combined power at one output port. The goal of this study is to design a millimeter-wave power divider operating at the range from 32 GHz to 34 GHz. The return loss at each port and the isolation between from output ports are required to be greater than 15 dB. The insertion loss need to be less than 3.1 dB. The concept of E-plane bifurcated waveguide is proposed to implement this millimeter-wave power divider because of the concerns about operation at high-frequencies and high-power handling, capacity. A resistive film is placed inside the bifurcated waveguide in order to meet the specifications of the proposed power divider. In addition, impedance transformation is employed at output ports to convert the output waveguide to standard waveguide.
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This manuscript details our latest 90nm CMOS W-band receiver design where the RF LNA, resistive mixer, IF differential amplifier and LO tripler have been integrated, thus allows the whole 77-110GHz spectrum to be down-converted into... more
This manuscript details our latest 90nm CMOS W-band receiver design where the RF LNA, resistive mixer, IF differential amplifier and LO tripler have been integrated, thus allows the whole 77-110GHz spectrum to be down-converted into quasi-DC -33GHz using a much lower microwave frequency. In addition to being used in our broadband receiver array project, this W-band circuit is also eligible for the conventional 77/94GHz vehicular and surveillance applications. This 90nm-CMOS receiver with LO tripler has around -0.4dB conversion gain, 18dB noise figure, 48dB LO-IF isolation, and its chip size is 950-times-750μm2, with 114mW power dissipation at 1.3V DC bias.
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In this article, we report the effect of nitrogen plasma, during and after deposition, on nitrogen incorporation into yttrium oxide dielectric films. Films are deposited using a yttrium β-diketonate precursor (Y(tmhd)3) introduced... more
In this article, we report the effect of nitrogen plasma, during and after deposition, on nitrogen incorporation into yttrium oxide dielectric films. Films are deposited using a yttrium β-diketonate precursor (Y(tmhd)3) introduced downstream from a O2 or N2 plasma. The precursor acted as a significant source of oxygen, and only small amounts of N (<10 at. %) were incorporated in the films. Chemical bonding, concentration, and distribution of N in Y-oxide films after deposition and after high-temperature anneal were characterized using x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and Auger electron spectroscopy. C–N is the primary form of nitrogen bonding in the as-deposited films, and IR results indicate the exchange of N with O to form C–O bonds occurs during prolonged exposure to air. High-temperature annealing releases N from the surface of as-deposited films, and results in a film structure that is resistant to further N incorporation. Results su...
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A new structure for a nonradiative dielectric (NRD) waveguide directional coupler has been developed. The structure combines two NRD guides and a dielectric slab guide in order to utilize a leakage mechanism for coupling. The coupling... more
A new structure for a nonradiative dielectric (NRD) waveguide directional coupler has been developed. The structure combines two NRD guides and a dielectric slab guide in order to utilize a leakage mechanism for coupling. The coupling depends on this leaky mechanism, but not on field interactions as in a conventional proximity coupler. A theoretical formula for calculation of the decay constant is derived. The field along the NRD guide and the decay constant are measured at Ka band (35 GHz) and compared with the theoretical data. Reasonable agreement between the measured and theoretical data is found. >
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Research Interests: Engineering, Electrical Engineering, High Frequency, Design method, Capacitance, and 7 moreTransistor, High Frequency and Monolithic Microwave Integrated Circuit (MMIC) Design, Insertion Loss, Electrical And Electronic Engineering, Electrical Impedance, Millimeter Wave, and High electron mobility transistor
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Interface stability of high dielectric constant gate insulators on silicon is an important issue for advanced gate stack engineering. In this article, we analyze the silicon/dielectric interface structure for thin Y2O3 and Y silicate... more
Interface stability of high dielectric constant gate insulators on silicon is an important issue for advanced gate stack engineering. In this article, we analyze the silicon/dielectric interface structure for thin Y2O3 and Y silicate films deposited by chemical vapor deposition on clean and prenitrided Si(100) using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and x-ray photoelectron spectroscopy. The analysis shows the films to be stoichiometric Y2O3 on top and Y-silicate/SiO2 at the dielectric/Si interface. Prenitridation of the silicon surface impedes the reaction between the depositing film and the substrate, promoting a Si-free Y2O3 structure. Possible mechanisms leading to the observed Y2O3 and Y silicate structures are discussed.
Research Interests: Engineering, Physics, Materials Science, Silicon, Transmission Electron Microscopy, and 13 moreX Rays, High Resolution Transmission Electron Microscopy, Thin Film, DIELECTRIC, Physical sciences, Energy Dissipation, Surface treatment, Dielectric Constant, Chemical Reaction, X Ray Photoelectron Spectroscopy, Electron Energy Loss Spectroscopy, Rough Surface, and Energy Spectra
High dielectric constant insulators deposited at low temperatures rapidly absorb water during exposure to the atmosphere, and the resulting OH leads to detrimental interface reactions. We report the effect of atmospheric exposure on... more
High dielectric constant insulators deposited at low temperatures rapidly absorb water during exposure to the atmosphere, and the resulting OH leads to detrimental interface reactions. We report the effect of atmospheric exposure on ultrathin yttrium oxide, and details of silicon substrate reactions during postdeposition anneals. Infrared absorption analysis indicates significant absorption of water vapor during atmospheric exposure, even for very short times (<15 min). X-ray photoelectron spectroscopy demonstrates that after OH absorption, a thermally activated interface reaction proceeds with an activation energy of 0.33 eV, consistent with substrate reaction with OH present in the film. The OH absorption rate is reduced for annealed films or when capping layers are deposited in situ. Similar oxidation processes are expected to occur in other high-k materials of interest, where the rate of OH absorption will depend on the deposition process and material thermal history.
Research Interests: Engineering, Materials Science, Silicon, Surface Chemistry, Thin Film, and 12 moreDIELECTRIC, Physical sciences, Activation Energy, Thermal history, Yttrium, Water Absorption, Dielectric Constant, Infrared spectra, Low Temperature, Thermal Activation, X Ray Photoelectron Spectroscopy, and Water Vapor
A novel structure for an NRD-guide directional coupler which combines two NRD guides and a dielectric slab is described. The coupling energy is carried by a leaky wave. Two different structures have been made and measured. For the first... more
A novel structure for an NRD-guide directional coupler which combines two NRD guides and a dielectric slab is described. The coupling energy is carried by a leaky wave. Two different structures have been made and measured. For the first structure, a dielectric slab is placed between two NRD-guides. For the second structure, the space between the lower and the upper metal plates is completely filled by Teflon. The field along the NRS-guide is measured at Ka-band (35 GHz) and compared with the theoretical results that have been obtained.
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We report the design of a wideband active power divider using commercial CMOS process. This circuit is made of two distributed amplifiers sharing a common input artificial transmission line while two distinct transmission lines are... more
We report the design of a wideband active power divider using commercial CMOS process. This circuit is made of two distributed amplifiers sharing a common input artificial transmission line while two distinct transmission lines are employed for the output ports. Since the input transmission line tends to be overly capacitive now when compared with the conventional distributed amplifier, the constituting