Showing papers on "Insertion loss published in 1995"

A Surface Micromachined Miniature Switch For Telecommunications Applications With Signal Frequencies From DC Up To 4 Ghz

Abstract: A surface micromachined miniature switch has been made on a semi-insulating GaAs substrate using a suspended silicon dioxide micro-beam as the cantilevered arm, a platinum-to-gold electrical contact, and electrostatic actuation as the switching mechanism. This switch functions from DC to RF frequency, and has an electrical isolation of -50 dB and an insertion loss of 0.1 dB at 4 GHz. The low process temperature budget of 250°C ensures the switch’s monolithic integration capability with microwave and millimeter wave integrated circuits.

Transmission characteristics of arrayed waveguide N/spl times/N wavelength multiplexer

Abstract: To realize practical wavelength division multiplexing (WDM) systems, a high-performance N/spl times/N wavelength multiplexer is introduced that is based on an arrayed-waveguide grating. Its transmission characteristics are theoretically derived and experimentally confirmed. A prototype is constructed using the previously proposed techniques that attain low insertion loss and polarization independent operation. It has 16 channels (N=16) with a spacing of 0.8 mn, or 100 GHz, in the 1.55-/spl mu/m band. Frequency relation between input and output ports, free spectral range, and passband width are determined. A demonstration of IM-DD pulse transmission shows that there is no degradation of bit error rate resulting from the finite passband width and crosstalk of the multiplexer. It is confirmed that the multiplexer can realize highly reliable N-channel WDM and WDM-based N/spl times/N interconnect optical networks. >

Polarization-independent all-fiber wavelength-division multiplexer based on a Sagnac interferometer.

Abstract: An all-fiber wavelength-division multiplexer (WDM) based on the nonreciprocity of the birefringence to the polarization states is proposed. The transfer function of a Sagnac interferometer is wavelength dependent if the loop birefringence of the interferometer consists of both circular and linear parts. Theoretical analysis shows that the output characteristics of this WDM are similar to those of a fiber taper-based device. Both the bandwidth and the peak wavelength of the new WDM can be tuned by changing the loop birefringence. Experimental prototypes exhibit a channel isolation greater than 25 dB with peak passband insertion loss of less than 1 dB.

Solidly mounted resonators and filters

Abstract: Acoustic resonators require material interfaces that confine waves to a finite volume in an efficient manner. Conventionally this is achieved by using air or vacuum interfaces at the electrodes. Another technique is to fabricate the resonator onto a set of quarter wavelength thick layers attached to a substrate to form a solidly mounted resonator (SMR). The SMR concept has been used to fabricate low insertion loss filters for GPS and other applications. Filters for GPS having less than 3 dB insertion loss and 40 dB out-of-band rejection have been demonstrated. These filters are composed of ladder networks with series and shunt resonators.

16-channel optical add/drop multiplexer using silica-based arrayed-waveguide gratings

Abstract: An optical add/drop multiplexer (ADM) that enables full access to 16 individual wavelength channels has been fabricated on a planar lightwave circuit (PLC). The device consists of three arrayed-waveguide gratings which are connected by 16 thermo-optic switches. The on-off crosstalk for the main input to the main output port is less than -24 dB and that for the main input to the drop port is about -13 dB. The fibre-to-fibre insertion losses are 7-8 dB and 3-4 dB when signals are coupled to the main input port and to the add port, respectively.< >

Fabrication of 64*64 arrayed-waveguide grating multiplexer on silicon

Abstract: A 64 channel arrayed-waveguide multiplexer with 0.4 nm (50 GHz) channel spacing at 1.55 µm has been fabricated using SiO2/Si waveguides. The authors obtained a crosstalk of less than –27 dB to neighbouring and all other channels. The on-chip insertion loss ranges from 3.1 to 5.7 dB for central and peripheral output ports, respectively.

A Ka-band circularly polarized high-gain microstrip array antenna

Abstract: In this article, the development of a circularly polarized microstrip array with 28 dBic of gain at 32 GHz is presented. Two primary objectives of this development are minimizing the microstrip array's insertion loss and maintaining a reasonable frequency bandwidth (3%). The parallel/series feed technique for the array's power distribution circuit and the sequential rotation method for the element arrangement are employed to meet these objectives. >

Integrated optical directional couplers in silicon-on-insulator

Abstract: Silicon-on-insulator (SOI) technology offers tremendous potential for integration of optoelectronic functions on a silicon substrate The authors have demonstrated an integrated 3 dB optical directional coupler using SOI rib waveguides The device has an excess insertion loss of 19 dB and represents a key component for the realisation of wavelength filters in silicon integrated circuit technology

Integrated-optic double-ring resonators with a wide free spectral range of 100 GHz

Abstract: Integrated-optic double-ring resonators with a wide free spectral range (FSR) of 100 GHz are fabricated using GeO/sub 2/-doped silica waveguides with a high relative refractive index difference (/spl Delta/) of 1.5%. The resonators are composed of two ring resonators comprising small ring waveguides with radii of 1.75 and 2.0 mm. The double-ring resonator module exhibited a wide FSR of 98.0 GHz, a finesse of higher than 138, a low crosstalk of less than -11.7 dB, and a low insertion loss of 6.1 dB. The measured FSR of 98.0 GHz is wider than any previously reported ring resonator composed of optical waveguides. >

High-power HTS microstrip filters for wireless communication

Abstract: The performance of narrowband microstrip filters with low insertion loss and high power-handling capabilities made from YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) high-temperature superconducting (HTS) thin films is presented. Results are shown for two different designs that were chosen to optimize the power-handling capability. Both filters have a 2-GHz center frequency and 5 poles that incorporate coupled resonators with 10-/spl Omega/ internal impedances. They were made on 5-cm-diameter LaAlO/sub 3/ substrates. Both designs use parallel-coupled feed lines to avoid current crowding, The first design includes backward- and forward-coupled filters, has 1% bandwidth, and has handled over 25 watts of input power at 10 K with less than 0.25 dB compression. The second design has 1.2% bandwidth and uses only forward-coupled resonators. The dissipation loss is less than 0.2 dB at 45 K and it has a third-order intercept of 62 dBm. Another similar filter handled 36 watts of power at 45 K with less than 0.15 dB compression across the passband. We have developed a technique to visualize the power dissipation of the filter by observing the bubbles created by the filter when submerged in liquid helium, showing areas with local defects or where the current distribution is at its peak value. We also discuss several planar high-power filter issues, including material selection and fabrication, device configuration trade-offs, filter structure optimization, and design approaches to maximize power-handling capacity.

Narrow-band acousto-optic tunable filtering in a two-mode fiber

Abstract: We demonstrate an optical filter that utilizes acousto-optic coupling between the spatial modes that propagate in a two-mode elliptical-core fiber. The optical bandwidth at 1090 nm is 0.85 nm, which is in agreement with predictions based on measurement of differential group delay between the modes. The filter is slightly polarization dependent, with a 0.28-nm wavelength difference between the passband peaks for the two polarization eigenstates. The optical insertion loss is dominated by 2-4-dB bending loss in nonoptimized mode strippers, and the coupling loss is negligible. Full acousto-optic mode conversion was achieved at an 8-mW electrical input power to the acoustic transducer.

Monolithic planar RF inductor and waveguide structures on silicon with performance comparable to those in GaAs MMIC

Abstract: The monolithic inductors and transmission lines on Si substrate with very high Q factor, low insertion loss, and high resonant frequency, are achieved by using very thick polyimide (10 /spl mu/m) as dielectric material, and thick Al (4 /spl mu/m) metalization system. This structure is made on the finished conventional standard two layer metalization BiCMOS wafer. For 10 nH inductor, 6 GHz resonant frequency, maximum Q factor of 5.5 at 1.2 GHz, and 1.2 dB insertion loss at 3 GHz are obtained, which are very comparable to those available in GaAs MMIC, These inductors can be used as RF choke as well as matching element. Transmission lines are also fabricated using this technology. The S/sub 21/ of coplanar waveguide with 1 mm length is -0.2 dB at 4 GHz, and that of microstrip line is -0.3 dB. It is expected that, using these passive elements, Si RF IC can be designed up to several GHz with performance comparable to GaAs MMIC.

WDM receiver by monolithic integration of an optical preamplifier, waveguide grating router and photodiode array

Abstract: A high performance monolithic WDM receiver is demonstrated. The chip receives eight optical channels spaced by 200 GHz. An optical amplifier at the input of the device boosts the incoming signal. A fibre insertion DC responsivity of 0.5 A/W and crosstalk below -20 dB are achieved. The receiver has a small signal bandwidth of 3.5 GHz.

Bending loss reduction in silica-based waveguides by using lateral offsets

Abstract: The excess loss that occurs in waveguide bends can be minimized by offsetting the connecting waveguides so as to reduce the transition loss at the junctions. Such bends were investigated in detail by employing the beam propagation method (BPM) and it was found that they can be optimized with respect to overall loss. In the addition, the S-shaped waveguides and directional couplers with offset junctions were fabricated based on silica-based planar lightwave circuits (PLC) on silicon substrates. The measured insertion losses of these S-shaped waveguides and directional couplers, which are in good agreement with the calculated results, are the lowest thus far reported. >

SPUDT-based filters: design principles and optimization

Abstract: Tremendous work has been done all over the world to overcome the difficult problems of triple transit and insertion loss in SAW filters. Most of research efforts towards low losses have consisted of introducing reflections in the filter designs. Two major classes of low loss filters have emerged during the past 20 years, resonator filters and Single Phase UniDirectional Transducer (SPUDT) filters. This paper reviews the design principles of this second class, including some representative examples of actual devices.

Narrowband lumped-element microstrip filters using capacitively-loaded inductors

Abstract: Coupling between microstrip resonators decreases very slowly as a function of the resonator separation. Therefore, it is difficult to realize narrowband filters (e.g., <0.1% fractional bandwidth) in reasonably sized microstrip form due to the very weak coupling values required. In this paper, we report a class of lumped-element filters that uses capacitively-loaded inductors to give frequency-dependent inductance values. A novel frequency transformation technique is used in the design process. Using this approach, filter bandwidth is determined by the inductance slope of frequency-dependent inductors, dL/d/spl omega/. Large coupling capacitance, thus small coupling element separations, can still be used in narrowband microstrip filters to keep the filter layout compact. We present a 5-pole, 0.27% bandwidth YBa/sub 2/Cu/sub 3/O/sub 7/ high-temperature superconducting thin film microstrip prototype filter at 900 MHz, which has 1.2 dB insertion loss and 20 dB return loss. It was designed with the coupling capacitors of a 1% bandwidth filter, and then transformed to a 0.27% fractional bandwidth using an appropriate inductance slope parameter, dL/d/spl omega/. Measurement showed good agreement with theory.

New uniplanar transitions for circuit and antenna applications

Abstract: New uniplanar microstrip-to-slotline, microstrip-to-coplanar strips (PS) and microstrip-to-coplanar waveguide (CPW) transitions for MIC/MMIC and slotline antennas for phased array applications are described. Such transitions are compact and suitable to be used in an open environment inside a package or a multichip module. The transitions share the concept of using a balun which consists of two microstrip lines connected to a slotline through a pair of coupled microstrips. In this paper, the transitions are studied theoretically using the Finite Difference Time Domain (FDTD) technique and measured experimentally using an HP8510C Network Analyzer. For a back-to-back microstrip-to-slotline transition, an insertion loss of less than 1.3 dB per transition is achieved over a 49% bandwidth with a minimum of 0.6 dB around the design frequency.

Active GaAs MMIC band-pass filters with automatic frequency tuning and insertion loss control

Abstract: This paper presents the design and measured performance of active tunable band-pass MMIC filters and matched MMIC control circuits, both fabricated using a standard 1-/spl mu/m GaAs MESFET foundry process. The control circuits generate filter frequency-tuning and Q-control bias voltages by using a dual-loop master-slave control scheme. Separate 3-section filters cover 1.5-2.0 and 1.96-2.64-GHz bands with 3-dB bandwidths of 86/spl plusmn/6 and 126/spl plusmn/1.0 MHz, respectively. The control circuits automatically maintain the filter insertion loss to within /spl plusmn/0.5 dB over these tuning ranges, and regulate the center frequency and insertion loss to within better than /spl plusmn/1.2 MHz and /spl plusmn/0.3 dB over a temperature range of -50/spl deg/C to +75/spl deg/C. >

Compact planar 980/1550-nm wavelength multi/demultiplexer based on multimode interference

Abstract: A compact integrated 980/1550-nm wavelength multi/demultiplexing coupler based on multimode interference effects is demonstrated. The device is useful for integration with rare-earth doped waveguide amplifiers and lasers. It is shown that the device performance can be optimized with an appropriate choice of the coupler width. The coupler is fabricated in a SiO/sub 2/-SiON deeply-etched rib waveguide system. Theoretical and experimental results for the demultiplexer configuration are presented. At an optimum coupler length of 458 /spl mu/m, contrast of about 18 dB, and on-chip insertion loss of 0.5 dB at both wavelengths are achieved. >

High-power high-temperature superconducting microstrip filters for cellular base-station applications

Abstract: We report narrowband microstrip filters with low insertion loss and high power-handling capabilities made from YBa/sub 2/Cu/sub 3/O/sub 7/(-x) high-temperature superconducting films. One 5-pole filter on a LaAlO/sub 3/ substrate, consisting of backward-coupled and forward-coupled resonators, can handle over 27 W input power at 10 K. It has 1% fractional bandwidth and 10-/spl Omega/ internal impedance. The insertion loss increase in passband at 10 K, as the input power changed from a few mW to 27 W, is less than 0.25 dB. We also report a forward-coupled microstrip filter centered at 2 GHz, with a 1.2% fractional bandwidth, 10-/spl Omega/ internal impedance, and parallel-coupled feed lines. We applied over 10 /spl Omega/ to the filter at 45 K without noticeable degradation of the filter performance. The insertion loss at 45 K is less than 0.2 dB. The return loss is better than 12 dB. >

Laterally tapered InP-InGaAsP waveguides for low-loss chip-to-fiber butt coupling: a comparison of different configurations

Abstract: Low-loss chip to-fiber coupling can be achieved by on-chip spot-size transformers. Two simple versions using laterally tapered InP-InGaAsP waveguides at the 1.55 /spl mu/m wavelength have been fabricated: one consisting of two differently tapered layers, the other with only one taper. The influence of the taper shape and of fabrication tolerances on their performance is compared both experimentally and theoretically. The optimum insertion loss for a single transformer without antireflection coating, including Fresnel losses, amounts to 1.1 dB. >

Ferroelectric phase shifters and their performance in microwave phased array antennas

Abstract: Recent advances in the development of Barium Strontium Titanate ferroelectric composition has made possible reasonable performance of ferroeletric phase shifters to frequencies up to 10 GHz. These material improvements, coupled with phase shifter circuit design changes have resulted in phase shifts greater than 360 degrees with less than 6 dB insertion loss. In particular additives to the BaxSr1-xTiO3 composition have been shown to exhibit a consistent electrical phase shift verses DC potential over parameters of temperature and humidity. These ferroelectric material improvements and circuit design changes, included with the development of multiple ferroelectric phase shifters makes possible the fabrication of a low cost electronic scanning antenna. A single four element phase shifter was used with a one dimensional linear antenna array which was constructed on three layers and used an aperture coupled distribution technique. Individual elements of this multiple four element phase shifter were ev...

MMIC active bandpass filters using varactor-tuned negative resistance elements

Abstract: This paper describes techniques for realizing microwave active filters using single transistor active resonators in a negative resistance configuration, The negative resistance topologies for both bipolar (AlGaAs/GaAs HBT) and FET (MESFET or HEMT) devices are studied and compared. The essence of the technique is that the input reactance of the transistor circuit resonates with an external capacitor or inductor, whilst the negative resistance is used to compensate for the losses in the resonator. It is shown that the FET device is ideally suited for this application as it can have a varactor-controlled negative resistance component. Three-stage and two-stage monolithic varactor-tuned bandpass filters have been demonstrated using this technique. The measured response of the three-stage filter exhibits a 120 MHz 3 dB-bandwidth centered on 2.3 GHz, 0 dB insertion loss with only /spl plusmn/0.1 dB ripple in the pass-band, up to 100 dB of stop-band attenuation at low frequencies, and over 50 dB of rejection up to 6 GHz. The two-stage filter exhibits a 400 MHz 3 dB-bandwidth centered on 4.7 GHz, with tunable insertion gain and only /spl plusmn/0.1 dB ripple in the pass-band.

Micromachined self-packaged W-band bandpass filters

Abstract: Experimental and theoretical results are presented for membrane supported W-band bandpass filters which utilize silicon micromachining technology to create self-packaged, shielded circuits. A coupled line shielded microstrip implementation of a 5-element 0.5 dB equal ripple Chebyshev filter achieves a minimum insertion loss of 3.4 dB with a 6.1% bandwidth centered at 94.7 GHz. The measured filter performance shows very sharp cutoff with out of band attenuation better than 25 dB and input return loss better than 8 dB. Results are also presented for a 5-element filter that achieves a minimum insertion loss of 2.2 dB with an 11.3% bandwidth centered at 94.7 GHz, and a 3-element filter with 1.3 dB insertion loss and 16.4% bandwidth at 94.9 GHz. Efforts to model filter performance using commercially available software and FDTD techniques are discussed. >

High quality ZnO thin films on InP substrates prepared by radio frequency magnetron sputtering. II. Surface acoustic wave device fabrication

Abstract: ZnO/InP based surface acoustic wave (SAW) devices were successfully fabricated High quality ZnO films were first deposited onto InP substrates by radio frequency magnetron sputtering, and the SAW devices were fabricated on top of ZnO It was found that the characteristics of the SAW devices depend strongly on the quality of the ZnO thin films and thus on the ZnO deposition parameters To obtain a low loss SW device, one must have a high quality ZnO thin film With a type I pattern, we found that the minimum insertion loss is 34 dB Inserting counter electrodes can further reduce the insertion loss to 23 dB

Coplanar stripline to microstrip transition

Abstract: A new coplanar stripline to microstrip line transition is experimentally demonstrated and modelled using the finite difference time domain technique, The measured insertion loss and return loss for two back-to-back transitions with a short length of microstrip line in between are better than 2.4 and –10 dB, respectively, over the frequency range of 5.1 – 6.1 GHz. The bandwidth of the transition is ~18 % at a centre frequency of 5.55 GHz.

Quasi-Microwave Band Longitudinally Coupled Surface Acoustic Wave Resonator Filters Using ZnO/Sapphire Substrate

Abstract: The 1.5 and 2.4 GHz range 5IDT-type longitudinally coupled surface acoustic wave (SAW) resonator filters have been developed using ZnO/sapphire substrate. The 1.5 GHz range SAW filter has the minimum insertion loss of 1.0 dB and the relative bandwidth of 2.4% at the insertion loss of 3 dB. The 2.4 GHz range SAW filter has the minimum insertion loss of 1.7 dB and the relative bandwidth of 1.7% at the insertion loss of 3 dB. These filters are suitable for use as RF-stage filters in a personal digital cellular (PDC) system terminal and a wireless local area network (LAN) adapter, respectively.

A 250-GHz microshield bandpass filter

Abstract: A four-section, planar bandpass filter has been designed, fabricated and tested at 130-360 GHz. The filter is based on the microshield line, a half-shielded transmission line in which the conducting lines are supported on a 1.4-/spl mu/m-thick dielectric membrane. The insertion loss of the filter is less than 1.5 dB with a 58% relative bandwidth at 250 GHz, demonstrating the excellent performance of the microshield geometry. Also, a Monte Carlo routine was developed in conjunction with a semi-empirical/semi-analytical model to allow the S-parameters of the filter to be derived from scalar power measurements. >