Insertion Loss Performance Research Articles

Design and analysis for a miniature CMOS SPDT switch using body-floating technique to improve power performance

A low insertion-loss single-pole double-throw switch in a standard 0.18-/spl mu/m complementary metal-oxide semiconductor (CMOS) process was developed for 2.4- and 5.8-GHz wireless local area network applications. In order to increase the P/sub 1dB/, the body-floating circuit topology is implemented. A nonlinear CMOS model to predict the switch power performance is also developed. The series-shunt switch achieves a measured P/sub 1dB/ of 21.3 dBm, an insertion loss of 0.7 dB, and an isolation of 35 dB at 2.4 GHz, while at 5.8 GHz, the switch attains a measured P/sub 1dB/ of 20 dBm, an insertion loss of 1.1 dB, and an isolation of 27 dB. The effective chip size is only 0.03 mm/sup 2/. The measured data agree with the simulation results well, including the power-handling capability. To our knowledge, this study presents low insertion loss, high isolation, and good power performance with the smallest chip size among the previously reported 2.4- and 5.8-GHz CMOS switches.

RF MEMS membrane switches on GaAs substrates for X-band applications

Micromechanical switches have demonstrated great potential at microwave frequencies. For low-loss applications at microwave frequencies, it is important to use high-resistivity substrates. This paper presents the design and fabrication of the shunt-capacitive MEMS switch on GaAs substrates. Analytical mechanical and impedance models of the membrane switch are given, and the results are confirmed by using the ANSYS and HFSS software, respectively. A surface micromachining process, which is compatible with the conventional millimeter-wave integrated circuits (MMICs) fabrication technology, was adopted to fabricate the RF switch on GaAs substrates. Its S-parameter was taken using a HP8510C vector network analyzer and a Cascade Probe station. The measured insertion loss of the switch and its associated transmission line is less than 0.25 dB from 1 to 25.6 GHz, and the isolation may reach -42 dB at its self-resonate frequency of 24.5 GHz. The actuation voltage is about 17 V. The switch has demonstrated lifetimes as long as 5/spl times/10/sup 6/ cycles. The wideband high performance in isolation and insertion loss offers the monolithic integration capability with GaAs MMICs.

Broadband MEMS shunt switches using PZT/HfO 2 multi-layered high k dielectrics for high switching isolation

A novel approach using a PZT/HfO 2 multi-layered dielectric for capacitive type MEMS switches was investigated. Compared to Si 3N 4, PZT/HfO 2 demonstrated a high equivalent dielectric constant of 79–82 and a low leakage current density of 1.58 × 10 −6 A/cm 2 after a bias stressing time of 10 4 s, that result in high switching isolation and very low power consumption. In addition, a finite element analysis was used to estimate actuation voltage, insertion loss and isolation performance of one-bridge and π-match switches. After manufacturing, the experimental results of the π-match switch showed an acceptable insertion loss of less than −0.5 dB in a frequency band of 50 MHz–20 GHz and significantly high isolation of −30 to −65 dB in a broad frequency band of 50 MHz–57 GHz.

Modified dual-mode double-ring resonators for wide band-pass filter design

A novel design of a dual-mode resonator with modified double rings structure for a wide band-pass filter is presented. Based on the mode chart and double rings resonator, modified double rings comprising three half rings are proposed. In addition each ring exhibits dual-mode responses, those rings determine the whole operating band; i.e. the smaller/larger rings depict the upper/lower frequencies of the pass-band and construct the flat of response for wideband applications. This is an alternative approach to achieve performance of low insertion loss, wide pass-band and sharp rejection band. Experimental and simulation results are presented and discussed.

A two-dimensional millimeter wave phase scanned lens utilizing analog electromagnetic crystal (EMXT) waveguide phase shifters

A novel type of waveguide phase shifter utilizing tunable electromagnetic crystal (EMXT) surfaces is incorporated in a 16-element two-dimensional (2-D) millimeter wave (38 GHz) phase-scanned lens. EMXT surfaces integrating semiconductor varactors are used as the sidewalls of a waveguide to provide a tunable impedance boundary for the waveguide. The EMXT waveguides are used as 360/spl deg/ analog phase shifters as well as radiating elements to realize electronic beam scanning with microseconds of response time. The four-by-four array achieved +/-30/spl deg/ of beam scanning in both the E and H planes. The electrical and mechanical design, top-level array calibration, and scan performance of the 16-element proof-of-concept 2-D space fed phased array lens are described. The waveguide phase shifter insertion loss performance and plans for further improving insertion loss are discussed. The average insertion loss is expected to be less than 2.0 dB at an operating frequency of 38 GHz for GaAs substrate-based EMXT surfaces with planar Schottky diode tuning elements. This new type of EMXT waveguide array may provide a low-cost and high performance alternative to a conventional phased array.

Design and experimental investigation of a wideband polarisation filter

The design of a wideband polarisation filter composed of a two-dimensional perforated flat conducting plate is presented. The experimental procedure used to verify the validity of the design algorithm is explained. The filter is used to suppress the cross-polarisation of both a horn antenna and a large array of dielectric resonators. Effective suppression of the cross-polarisation (in the order of 15 dB) was observed for both cases. The insertion loss is in the order of 2 dB in the case of the horn, and 0.6 dB in the case of the array antenna. The 10 dB return loss bandwidth is measured to be 15%. It is demonstrated that the filter can be installed in close proximity to the antenna radiating aperture without any significant degradation in its insertion loss or polarisation isolation performance.

High performance thermo-optic switches based on low-loss acrylate polymers

We design and fabricate digital thermo-optic switches using low-loss photocuring fluoroacrylate polymers. We use both modeling and experimental design-rule studies to elucidate the contributions to loss and cross talk of the various important building blocks that comprise a Y-branch digital optical switch (YDOS). We present the results of these studies as well as the achieved performance for 1×2, 2×2, and 4×4 switches fabricated with these designs. Average fiber-to-fiber chip- level insertion loss (IL) values for the three designs are 1.1, 1.5, and 2.8 dB, respectively, for 1550-nm illumination. Switching times in every case are below 3 ms. Polarization-dependent loss is less than 0.1 dB at 1550 nm. Fully packaged permanently pigtailed versions of the 2×2 and 4×4 switches are also constructed. For these packaged devices, average insertion losses of 2.0 and 3.3 dB are achieved, and cross talk is maintained at a value less than –45 dB. Recent advances in materials performance have now allowed the insertion loss performance to be further improved, with chip-level IL being reduced to 1.0 and 2.2 dB for 2×2 and 4×4 switches, respectively.

High Performance RF Passive Integration on a Si Smart Substrate for Wireless Applications

To achieve cost and size reductions, we developed a low cost manufacturing technology for RF substrates and a high performance passive process technology for RF integrated passive devices (IPDs). The fabricated substrate is a conventional 6' Si wafer with a 25 μm thick Sio 2 surface. This substrate showed a very good insertion loss of 0.03 dB/mm at 4 GfIz, including the conductive metal loss, with a 50 Ω coplanar transmission line (W=50 μm, G=20 μm). Using benzo cyclo butene (BCB) interlayers and a 10 μm Cu plating process, we made high Q rectangular and circular spiral inductors on Si that had record maximum quality factors of more than 100. The fabricated inductor library showed a maximum quality factor range of 30-120, depending on geometrical parameters and inductance values of 035-35 nH. We also fabricated small RF IPDs on a thick oxide Si substrate for use in handheld phone applications, such as antenna switch modules or front end modules, and high-speed wireless LAN applications. The chip sizes of the wafer-level-packaged RF IPDs and wire-bondable RF IPDs were 1.0-1.5 mm 2 and 0.8-1.0 mm 2 , respectively. They showed very good insertion loss and RF performances. These substrate and passive process technologies will be widely utilized in hand-held RF modules and systems requiring low cost solutions and strict volumetric efficiencies.

Noise Reduction Techniques for Close-fitting Enclosures at Structural/Acoustic Resonance

In this paper, a close-fitting enclosure model is used to prove the existence of a common structural-acoustic coupling experimentally, which deteriorates the insertion loss performance but was not considered in the formulas developed by Refs.(1)-(3) and the classical formula used in Refs.(4)-(6). The experimental results show that an enclosure, which first anti-symmetric structural and acoustic resonant frequencies do not coincide or nearly coincide, can avoid strong structural-acoustic couplings within the air cavity. At the acoustic resonance frequencies, the insertion loss performance of an enclosure can be improved by using the aluminum fiberboard, porous aluminum, and perforated aluminum panel to absorb the sound energy. Stiffener is useful to enhance the insertion loss ability of an enclosure if the dominant frequency bands of the noise are below the first structural resonant frequency. For having good damping effect to suppress the noise radiation at structural resonant frequencies, an enclosure should be mounted with both stiffeners and damping treatments.

In-fiber nematic liquid crystal optical modulator based on in-plane switching with microsecond response time

We describe a simple method and device design that enables fast in-plane electro-optic modulation in conventional nematic liquid crystal (NLC) devices. When combined with optimized NLC materials, this approach yields rotational speeds of 1°/μs (independent of rotation angle, over a wide range) at a moderately low voltage. The observed rotational dynamics indicate that even these high speeds may not represent fundamental physical limits. We demonstrate these ideas in a compact tunable NLC waveplate that uses microelectrodes patterned directly on the tips of optical fibers. These devices offer fast, continuously tunable optic axis with low insertion loss and good performance in the near infrared. Modulators that use this design have promising potential applications for polarization control and analysis in optical communication systems.

INSERTION LOSS OF A CAVITY-BACKED SEMI-CYLINDRICAL ENCLOSURE PANEL

In this paper, the insertion loss of a cavity-backed semi-cylindrical enclosure panel is studied theoretically and experimentally. The classical approach based on Narayanan [1] and Lee [2] is employed to the semi-cylindrical enclosure modelling. The theoretical model considers the three-dimensional acoustic modes of the semi-cylindrical cavity and the noise source vibration mode shape. The experimental result agrees reasonably with the theoretical prediction. It is found that the higher structural resonance in the semi-cylindrical can significantly deteriorate the insertion loss performance while only the (1,1) mode structural resonance in the rectangular models is the important one. The noise source panel vibrating in the (3,1) mode shape induces higher air pressure on the semi-cylindrical panel through the air cavity than the (1,1) mode shape.

An X-band small outline leaded plastic package for MMIC applications

A new small outline (SO) leaded plastic package has been developed that improves return loss, insertion loss, and isolation performance over that of a shrink small outline package (SSOP) in the same body size. A custom TRL calibration kit was developed, and prototype packages built and measured. The measured package showed an increase in the application bandwidth of SO-type packages from 5 GHz to over 8 GHz. Further investigations using full-wave electromagnetic simulations reveal a potential increase in return loss of better than 30 dB to 10 GHz, giving the package a usable bandwidth well into the X-band (8-12GHz). Applications for the new package are in microwave and RFIC applications.

Low-loss distributed MEMS phase shifter

This letter presents a one-bit low-loss K/K/sub a/-band phase shifter circuit that employs microelectromechanical systems (MEMS) capacitors. The measured results demonstrate a delay line with a 180/spl deg/ phase shift/1.l7 dB loss phase shift at 25 GHz, 270/spl deg/ phase shift/1.69 dB loss at 35 GHz, and a return loss better than 11 dB over a 0-35-GHz band. The state-of-the-art insertion loss performance, 154/spl deg//dB at 25 GHz and 160/spl deg//dB at 35 GHz, demonstrates the potential for the implementation of a very low-loss multibit digital MEMS phase shifter.

Novel V-groove-based interconnect technology

A novel fiber optic interconnect technology based on injection molded V-grooves that uses the fiber’s inherent precision to provide a reliable, robust and consistent optical connection is described. This technology has been expanded and applied to optical transceivers that can now achieve the same port density as that of current copper-based systems. Both the interconnect and the optical transceivers are shown to have performance levels similar to current ferrule-based multimode technology. Testing was performed in an effort to accurately measure performance and qualify the connector design for field use. Test results for the interconnect met the performance requirements of Electronics Industry Association/Telecommunications Industry Association (EIA/TIA) 568, which represent test standards for local area networks. Results of insertion loss and return loss performance of the duplex ferrule-less connector design were measured when 400 unique links were tested using 62.5 mm multimode fiber. Mating durability performance tests were performed in which plugs were reconnected to the socket 500 times. A new generation of small form factor transceivers is discussed that were developed using the same V-groove technology. Optomechanical tests are reported that show the performance level of these new transceivers is comparable to existing ST transceiver technology.

Low loss multilayer microstrip line for monolithic microwave integrated circuits applications

This paper describes the multilayer microstrip structure using low dielectric constant polyimide as a buffer layer between the microstrip conductor and the GaAs substrate to reduce dissipation loss, especially for very high impedance microstrip lines. The new structure provides about half the dissipation loss and about 40% higher characteristic impedance in comparison to the conventional microstrip line on GaAs substrate having the same conductor widths. An empirical formula for the equivalent dielectric constant compatible with commercial computer-aided design tools was developed to design monolithic microwave integrated circuits (MMICs) using this medium. The multilayer microstrip structure is compatible with ITT's 4′ MSAG® process which uses polyimide for crossovers and scratch protection. The present structure has great potential in realizing low loss and wideband matching networks including low noise, high power, and high efficiency amplifiers, and passive components on GaAs substrate with improved insertion loss and bandwidth performance, and three-dimensional MMICs. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 441–454, 1998

SOUND INSERTION LOSS OF STIFFENED ENCLOSURE PLATES USING THE FINITE ELEMENT METHOD AND THE CLASSICAL APPROACH

This paper reports a theoretical and experimental study of insertion loss of stiffened enclosure plates which are used for noise control in industrial machines, automobiles, trains and aircrafts. The theoretical analysis is based on the finite element method in [1] for the structural part, and the classical solution suggested in [2, 3] for the acoustic part. The effects of boundary conditions, acoustic resonance and structural resonance on the insertion loss are studied. The theoretical results agree reasonably well with the experimental results. Both numerical and experimental results point to two important findings: 1) the coupling effect between the (1, 0) acoustical mode and the (2, 1) structural mode is an important factor which can cause deterioration of the insertion loss of an enclosure plate; and 2) stiffeners can be used to enhance the insertion loss ability of an enclosure plate at the frequencies below the fundamental resonance. However, at other frequencies, the enclosure plate could give worse insertion loss performance.

A high-Q broad-band active inductor and its application to a low-loss analog phase shifter

The proposed high-Q broad-band active inductor utilizes frequency-insensitive negative resistance to compensate constant internal losses caused by the drain-to-source conductance of the field-effect transistors (FETs), the dc bias circuit, and several other factors. The measured frequency range of the fabricated InAlAs/InGaAs/InP HEMT active inductor is 6 to 20 GHz for Q values greater than 100, and 7 to 15 GHz for Q values greater than 1000. A low-loss analog phase shifter is also fabricated at C-band. This is constructed with the active inductors, the varactor diodes and the low-loss multilayer broad-side coupler in a MIC structure. Since the constant negative resistance of the active inductors also compensates the line loss of the coupler and the varactor diodes' series resistance, the measured results show a good insertion loss performance with a large phase shift. A phase shift of more than 225/spl deg/ within a 0.8 dB insertion loss from 4.7 to 6.7 GHz, another of more than 180/spl deg/ within 1.3 dB insertion loss from 3.7 to 8.5 GHz, and one more of more than 90/spl deg/ within 1.4 dB insertion loss from 3.5 to 10.6 GHz were obtained.

Loss and reflectance of standard cylindrical-ferrule single-mode connectors modified by polishing a 10 degrees oblique endface angles

It is shown that the reflectance performance of existing, cylindrical, keyed, single-mode fiber connectors can be significantly improved by polishing 10 degrees oblique endfaces. This results in a maximum of -60 dB to less than -70 dB reflectance. Due to the resulting air gaps and hence multiple beam interference, the average insertion loss increase compared to physical-contact-type connectors is 0.43 dB. This is in excellent agreement with the predicted value of 0.45 dB for this type of joint. In cases where insertion loss performance is not the limited factor, this straightforward modification of standard cylindrical connectors shows potential for use in bidirectional and/or analog AM transmission systems. When the additional insertion loss cannot be tolerated, design changes in endface profiles and keying features may also be required. If fiber-to-fiber endface contact can be achieved, the same excellent reflectance performance will be achieved even with the presence of a modified index layer on the endface.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Scattering from multiple gratings of compliant tubes in a viscoelastic layer

Previous studies of scattering from multiple gratings of resonant compliant tubes in water determined that noncompliant, antisymmetric structural modes excited by evanescent waves severely degraded the reflectivity of closely packed gratings. Also, low-frequency performance was diminished by transmission resonances due to the spring–mass–spring configuration of the two compliant gratings separated by a fluid mass. In this paper, encapsulating a single grating in a layer of elastomer whose shear properties are well below its rubber–glass transition region is shown to only reduce the maximum insertion loss. For two gratings, both the transmission resonances and the evanescent wave excitations are mitigated by encapsulation in a rubberlike material. Insertion loss performance with an encapsulant whose shear properties are in the rubber–glass transition region occurs at reduced bandwidths and shifted frequency responses. The mathematical model for gratings in fluid is extended to include the viscoelastic layer and calculations from this model are compared with experiments.

Prediction of optimal active noise controllers using boundary element methods

Boundary element methods have been used as numerical approximations of boundary integral equations to predict the sound fields in complicated three‐dimensional interior and exterior spaces. In this investigation the methods have been investigated for their capability to find and evaluate the optimal active noise controller for complex acoustic geometries. The boundary element methods are utilized to enforce the specified boundary conditions while solving for the optimal secondary source distribution necessary to minimize a giver performance equation. For the current work the performance equation is a weighted sum of mean‐square pressures at specified points. Thus the method can predict the optimal controller required to achieve local control using a single point, or to achieve a space averaged reduction by using a distribution of points. The formulation allows multiple secondary sources and either pressure, velocity, or normal specific acoustic impedance boundary conditions. The optimal secondary source's strengths and the insertion loss performance of several active controller configurations are illustrated.