Analysis of the nonlinear coaxial coupler

The authors present an analysis of the nonlinear properties in the coaxial fiber coupler. Two approaches are used, numerical beam propagation calculations in the radially symmetric waveguide and analysis of the coupled equations describing the interaction of the local modes. The two methods are compared and the region of validity of the local node analysis is then determined. They examine in detail the critical power condition for this structure and show how the design considerations to achieve this conditions can be understood     

Design and analysis of DC-to-14-GHz and 22-GHz CMOS cascode

The designs of two fully integrated CMOS cascode distributed amplifiers (DAs) with 14-GHz and 22-GHz bandwidth are presented. Cascode gain cells and m-derived matching sections are used to enhance the gain and bandwidth performance. These amplifiers demonstrated the highest frequency and widest bandwidth of operation for amplifiers using regular CMOS processes to date. This paper also describes the analysis to design the cascode CMOS DA, together with the small-signal models, EM simulation of the spiral inductors on the silicon substrate, and the analysis of the cascode device. Good agreement between measured and simulated results was achieved for both of the DA designs.     

Particle Simulation of a 35-GHz Third-Harmonic Low-Voltage Complex Cavity Gyrotron

A self-consistent particle simulation code has been developed for the research of a 35-GHz third-harmonic Low-voltage complex cavity gyrotron. Aided with microcomputer we use FORTRAN to simulate the process of interaction between electron beam and electromagnetic field. About 7000 macro particles are included at the same time. In the program many useful physical graphs are accessible for the further research of this kind of gyrotron such as the field profile, electrons distribution in various spaces, output power, efficiency and et al. Such simulation results may be helpful to the optimization of devices operation parameters     

Design of a tapered coaxial resonator filter for mobilecommunications

The authors describe the design, a simple fabrication technique, and performance of a coaxial resonator filter with tapered inner conductors to be used in mobile radios. The effects of coupling, window area, and temperature on the performance of the filter have also been considered. The passband of the filter is 30 MHz with a center frequency of 925 MHz, 1.15-dB insertion loss, 0.8-dB ripple, and 14.7-dB return loss at the center frequency. The resonant frequency and coupling coefficient stabilities with temperature have been measured at 28.38 ppm/°C and 3.5×10^-4/°C, respectively. The 3-dB bandwidth is measured as 32 MHz and a sharp cutoff is observed at -16.5 dB with a bandwidth of 37 MHz for narrow scale and -65 dB with a bandwidth of 84 MHz for wide scale. The fabrication technique developed using a zinc-cast inner conductor and extruded aluminum outer conductor has better reproducibility than the conventional machining technique and is highly cost effective     

35-GHz performance of single and quadruple power heterojunction HEMT's

The potential of single hetrojunction (SHJ) and quadruple heterojunction (QHJ) HEMT devices to provide power amplification at theKa-band frequencies has been measured. The power level observed, from QHJ devices that have gate lengths of 0.5 µm and gate widths of 200 µm, has been over +20 dBm when gain is compressed below the small signal level by 2 dB. The small-signal gain was 5.2 dB at 35 GHz. The power level demonstrated by the SHJ devices is lower than that of the QHJ devices due to the lower "two-dimensional electron gas" sheet carrier density. Our measurements have shown a saturated power level of +15.3 dBm devices of the same geometry as the above-mentioned QHJ devices. The power performance in both cases (QHJ and SHJ) has been obtained with high efficiencies of 38 and 21 percent, respectively. These performance data represent the highest levels of gain and power reported atKa-band frequencies from transistors that employ a 0.5-µm geometry.     

Design and Performance of a 45-GHz HEMT Mixer

A 45-GHz single-ended HEMT mixer has been developed with unity gain and 7-8-dB SSB noise figure over a 2-GHz bandwidth, including an IF amplifier, and 2-dBm output intermodulation intercept. This paper describes its design, structure, and performance. High performance has been achieved by careful attention to the design of the input and output embedding networks. This is the first reported HEMT mixer and the first active mixer above 30 GHz.     

Design parameters of a high-efficiency 1.7-GHz gyropeniotronamplifier

The feasibility of the gyropeniotron amplifier as a high-efficiency, high-power RF source to act as driver for accelerator in the 0.8-1.7-GHz frequency range is discussed. The klystrode is difficult to operate in this frequency range. Design parameters are given for a 1.7-GHz gyropeniotron operating with an axis-encircling beam (100 keV, 10 A) in a magnetron-type slotted waveguide. The external magnetic field required is 326 G. The calculated efficiency for second cyclotron harmonic operation is 78% with a cold beam and 66% with a beam having 2% axial velocity spread and 5% guiding center spread. The depressed collector technique can easily be applied to enhance the efficiency since the spent beam in a gyropeniotron has little velocity spread     

A 35-GHz Isolator Using a Coaxial Solid-State Plasma in a Longitudinal Magnetic Field

The device considered in this study is a semiconductor isolator consisting of a circular waveguide with a cylindrical rod of n-type InSb mounted coaxially in the guide. To achieve nonreciprocal operation, the InSb was cooled to liquid nitrogen temperature, a dc magnetic field was applied parallel to the direction of propagation, and a circularly polarized signal was used to excite the waveguide containing the rod. The pertinent solution of Maxwell's equations was programmed for a digital computer to allow numerical evaluation of the characteristics of the isolator using an InSb rod in which losses were present. Experimental data for various parameters and the corresponding calculated data are presented and compared. Low forward loss is achieved with the present coaxial geometry because of strong power concentration effects within or outside of the InSb rod as a function of the direction of propagation. Two series of calculated mode patterns are presented that demonstrate two types of operation of the isolator in achieving a high loss for one direction of propagation, one depending on field displacement, the other on mode coupling. These data are again compared to the experimental evidence.     

Design of wavelength-flattened coupler using a novel diagram

A novel diagram which describes the condition of 3 dB coupler is proposed. Using the proposed diagram, the design of a wavelength-flattened 3 dB directional coupler composed of a uniform coupled waveguide is investigated. Normalized waveguide parameters are introduced to characterize a five-layer planar waveguide. This enables us to generalize the discussion and to reduce the number of parameters required for characterizing a coupled waveguide. A broadband 3 dB coupler having 50±5% coupling ratio over a wavelength range of 1.1-1.7 μm is designed     

Design criterion for low-loss optical coupler tapers

A criterion for the local taper angle of a low-loss single-mode fibre coupler is established by considering the dominant mode coupling in the coupler taper. Effects due to structure parameters, such as cladding/core thickness ratio, corecladding index difference and core separation, are investigated. It is found that the criterion for the coupler taper can be well approximated by that for the single-mode fibre taper with the same structure parameters.     

A monolithic 5.9-GHz CMOS I/Q direct-down converter utilizing a quadrature coupler and transformer-coupled subharmonic mixers

We report the first monolithic 5.9-GHz CMOS I/Q direct-down converter by using a quadrature coupler and transformer-coupled subharmonic mixers (SHMs). Consuming 3.5mW, each SHM achieves a voltage gain of 10.8dB, 7.9-dBm IIP3, and 54-dBm IIP2. The input-referred dc-offset due to local oscillator self-mixing is -80.9dBm.     

35-GHz static and 48-GHz dynamic frequency divider ICs using0.2-μm AlGaAs/GaAs-HEMTs

Two static and two dynamic frequency dividers based on enhancement and depletion 0.2-μm gate length AlGaAs/GaAs-high electron mobility transistor (HEMT) (f_T=60 and 55 GHz) technology were designed and fabricated. High-speed operations up to 35 GHz for the static frequency dividers and 48 GHz for the dynamic dividers, respectively, have been achieved. The single-ended input and differential outputs to ground simplify many applications. The power consumption is 250 mW for the divide-by-two dividers and 350 mW for the divide-by-four dividers using two supply voltages of 4 and -2.5 V     

Theoretical investigation of an advanced launcher for a 2-MW 170-GHz TE/sub 34,19/ coaxial cavity gyrotron

This paper investigates the antenna waveguide (launcher), the main component of the quasi-optical mode converter of a 2-MW 170-GHz TE/sub 34,19/ coaxial cavity gyrotron, which is under development within the European Union. For coaxial gyrotrons operating in very high-order cavity modes like the TE/sub 34,19/, due to the ratio of the caustic to cavity radius of 0.323, the transformation of the high-order cavity mode into a nearly Gaussian distribution cannot be done as good as for gyrotron modes where the ratio of caustic to cavity radius is approximately 0.5. The simulation results for the TE/sub 34,19/ mode show that the average and peak values of the power density at the edges of the cuts of a conventional dimpled-wall launcher are approximately 32.3 W/cm/sup 2/ and 63.8, respectively, which will produce diffraction losses and reflection of power from the cuts. This paper reports on an advanced launcher for which average and peak values of power density of 1.9 and 5.4 W/cm/sup 2/ at the edges of the cuts are achieved, and a well-focused field at the aperture with a scalar Gaussian mode content of 94.8% is obtained.     

Design and Analysis for a 60-GHz Low-Noise Amplifier With RF ESD Protection

An RF electrostatic discharge (ESD) protection for millimeter-wave (MMW) regime applied to a 60-GHz low-noise amplifier (LNA) in mixed-signal and RF purpose 0.13-$mu{hbox{m}}$ CMOS technology is demonstrated in this paper. The measured results show that this chip achieves a small signal gain of 20.4 dB and a noise figure (NF) of 8.7 dB at 60 GHz with 65-mW dc power consumption. Without ESD protection, the LNA exhibits a gain of 20.2 dB and an NF of 7.2 dB at 60 GHz. This ESD protection using an impedance isolation method to minimize the RF performance degradation sustains 6.5-kV voltage level of the human body model on the diode and 1.5 kV on the core circuit, which is much higher than that without ESD protection ( $≪$350 V). To our knowledge, this is the first CMOS LNA with RF ESD protection in the MMW regime and has the highest operation frequency reported to date.      

SMA型超轻射频同轴连接器的设计

介绍了一种SMA型超轻射频同轴连接器,由于使用环境的特殊性,需要采用细长杆结构且要求重量尽可能轻,因而在连接器结构上进行了着重考虑,并对结构强度和电性能参数进行了仿真分析。     

Design and performance of active coupler for plastic optical fibres

A simple and successful design of a new active coupler for plastic optical fibres (POF) is presented. It consists of a 2×2 coupler with a polymer-dispersed liquid crystal (PDLC) film sandwiched in it, which takes advantage of the electrooptic effect of the PDLC. More than 3 dB of variation can be achieved by applying electric fields below 1.5 V/μm     

工作在0.5V电压下用于无线传感网的低噪声放大器设计与优化

本文阐述了一款用于无线传感器网络可工作在0.5V电压下的低噪声放大器芯片的设计和优化方法。该芯片采用0.13 um CMOS工艺实现。本文中对其电路进行了详细分析,并提出了一种新的优化设计方法。该芯片的测试结果显示,此款低噪声放大器的功率增益为14.13dB,噪声系数最低为1.96dB,直流功耗3mW,输入1dB压缩点为-19.9dBm。S11和S22均在-10dB以下。测试结果显示此款低噪放完全适用于低电压低功耗应用。     

Design and fabrication of a significantly shortened multimode interference coupler for polarization splitter application

We report that we have successfully designed and fabricated a significantly shortened multimode interference coupler for application in polarization splitter, using a phenomenon that we termed "quasi-state" (QS) imaging effect. First, we identified and analyzed the QS imaging effect, and, based on the QS analysis, designed and fabricated a novel multimode interference (MMI) device with its split length shortened to 1/5 of a normally designed MMI split length. The fabrication is simple and cost effective and the fabricated device shows outstanding characteristics in extinction ratio, signal homogeneity, excess loss, and tolerance in the length of the splitter.     

Design of a wide-band lumped-element 3-dB quadrature coupler

Analysis and design techniques for designing a lumped-element 3-dB quadrature coupler with wide-band flat coupling are proposed for microwave integrated-circuit/monolithic-microwave integrated-circuit applications. The proposed design technique can produce a coupler with flat coupling over 50% fractional bandwidth, which is wider than the conventional lumped-element design methods. A prototype consisting of a capacitive coupled high-pass network is designed and fabricated to verify the design concept. Measurement and simulation results closely correspond to each other