Multiple Branch-Guide Directional Coupler Using TE/sub 01/-Mode Semicircular Waveguide (Short Papers)

This short paper describes experimental results derived from a newly devised branch-guide directional coupler using a TE/sub 01/-mode semicircular waveguide. The length of an experimental 0-dB coupler is about 150 mm, which is one-third shorter than the conventional coupled wave-type 0-dB coupler, and the loss is decreased in proportion to the reduction in length. Using this coupler, it is possible to manufacture more compact millimeter-wave diplexers with reduced insertion loss.     

Slot-Coupled T-junction of TE/sub 11/ Coaxial to TE/sub 10/ Rectangular Waveguide

A solution is presented to the problem of a slot-coupled T-junction of a TE/sub 11/ -mode coaxial to a TE/sub 10/ -mode rectangular waveguide. A variational technique is employed which combines the reaction concept with the field representation of a waveguide slot and leads to a closed-form solution for the junction scattering matrix. Numerical examples illustrate the characteristics of such a junction in practical applications. Good agreement between theory and experiment is obtained. Design criteria and examples are presented and discussed.     

Theory and Design of a Ku-Band TE/sub 21/-Mode Coupler

This paper describes a TE/sub 21/-more tracking coupler for satellite earth stations communications antennas which require autotrack capability. The paper covers theoretical coupler designs as well as laboratory test results from Ku-band hardware.     

End Plate Modification of X-Band TE/sub O11/, Cavity Resonators (Correspondence)

In the application of microwave refractometers, the sampling cavity consists of a right circular cylinder whose parallel faces are partially opened to permit air flow. The ambient air is aspirated through the cavity, and the instrument measures a weighted average of the index of the air contained at any time within the cavity.     

TeO/sub 2/-based glasses containing Nb/sub 2/O/sub 5/, TiO/sub 2/, and WO/sub 3/ for discrete Raman fiber amplification

We describe a highly stable glass family based on the combination of TeO/sub 2/ with heavy metal-oxides of Nb, Ti, W. We show that these glasses have large Raman gain, a broad Raman spectrum, and large negative dispersion. They are, thus, potentially useful in a variety of specialty fiber applications, such as discrete Raman amplification.     

Precise Millimeter-Wave Measurements of Complex Refractive Index, Complex Dielectric Permittivity and Loss Tangent of GaAs, Si, SiO/sub 2/, A1/sub 2/O/sub 3/, BeO, Macor, and Glass

Highly accurate continuous spectra of the complex refractive index and complex dielectric permittivity are given in the millimeter range for a variety of potentially useful materials. The absorption coefficient is found to increase monotonically with increasing frequencies. Small amounts of glassy inclusions or water were found to increase losses at all frequencies, but impurities and radiation damage (except in semiconductors) have not yet proved to be detrimental to performance. Materials have been found for which the millimeter-wave losses can be tolerated when used as dielectric waveguide, high-power windows, and other applications. Nominal consideration must be given, however, to the conditions of preparation and the nature of contaminants, The measurements were made in a modular, polarizing, dispersive Fourier-transform spectrometer.     

TE /sub 11/ to HE /sub11/ Cylindrical Waveguide Mode Converters Using Ring-Loaded Slots

A theoretical parameter study is given of a TE/sub 11/ to HE/sub 11/ mode converter consisting of a section of cylindrical corrugated waveguide with ring-loaded slots. The analysis, using modal field-matching techniques to determine the scatter matrix of the converter, allows the return loss to be computed accurately. For a wide range of waveguide sizes it is shown that a bandwidth ratio of 1.5 with a return loss better than 30 dB is possible. The low-frequency performance of the converter is limited by the deterioration in return loss, while at high frequencies the generation of a small amount of unwanted EH/sub 12/ mode is the restriction. If the effects of this mode can be neglected, operation over a wider bandwidth is possible, particularly for larger waveguide size.     

10-DB X/sub L/ Cross Guide Coupler (Correspondence)

Two interesting points were noted while working with half-height cross guide couplers. The first was that if the same size coupling holes were used as in the full size waveguide, coupling was increased approximately 3 db. The second, and more important, was that the value of coupling was much more constant over a given frequency band, with essentially no change in directivity.     

基于绝缘体上硅脊型纳米线光波导方向耦合器的TE/TM偏振分束器

利用有限元方法和时域有限差分方法,优化设计了一种结构紧凑的基于绝缘体上硅脊型纳米线光波导方向耦合器的TE/TM偏振分束器。考虑到方向耦合器的波导间隙较小时制作工艺较为困难,且模式失配会引入一些损耗,因此波导间隙取约100nm较为合适。通过优化脊型纳米线光波导的几何尺寸(脊高和脊宽)、耦合区波导间隙,使得偏振分束器长度最短。数值计算结果表明经过优化的偏振分束器最短长度大约为17.3μm,偏振分束器的消光比大于15dB时,波导宽度制作容差为-20～10nm,带宽约为50nm。     

Circular TE/sub 011/Mode, Trapped-Mode Band-Pass Filters

Band-pass filters are described which utilize a novel type of resonator which has been named a "'trapped-mode resonator." This type of resonator uses a structure which is open on its sides so that energy in all but a single desired mode tends to radiate out to energy-absorbing material. However, energy in the desired resonator mode is trapped within the structure and a high-Q resonance occurs, such as is typical of conventional microwave cavity resonators. The use of resonators of this type makes possible the design of band-pass microwave filters which have a pass band similar to that of other multiresonator microwave filters, but without the many unwanted pass bands which are typical of microwave filters. The particular type of filter discussed utilizes the circular TE/sub 011/ mode. Several experimental filter structures of this type were constructed, and the results of laboratory tests are described.     

MIC Coupler with Improved Directivity Using Thin-Film Bi/sub 2/O/sub 3/ Overlay (Letters)

Results of the effect of thin-film Bi/sub 2/O/sub 3/ overlay on a directional coupler at X band are reported. Directivity between 14 and 23 dB was obtained over the band.     

Quarter-Wavelength Coupled Dielectric Plate Resonators for High Selectivity TE/sub 10/-Mode Filters

An analysis of high selectivity TE/sub 10/-mode filters with quarter-wavelength coupled resonators formed by axially spaced dielectric plates is presented and shows that high-loaded quality factors of individual resonators can be obtained by placing the resonant frequency close to the waveguide cutoff frequency and by using low-loss Iow-dielectric constant materials. Design equations for Butterworth and Chebyschev filters are presented and employed in a three-cavity Butterworth filter having 30-MHz bandwidth at resonant frequency at 7250 MHz. Experimental results show that filter performance can be well predicted.     

Low-frequency noise in submicrometer MOSFETs with HfO/sub 2/, HfO/sub 2//Al/sub 2/O/sub 3/ and HfAlO/sub x/ gate stacks

Low-frequency noise measurements were performed on p- and n-channel MOSFETs with HfO/sub 2/, HfAlO/sub x/ and HfO/sub 2//Al/sub 2/O/sub 3/ as the gate dielectric materials. The gate length varied from 0.135 to 0.36 /spl mu/m with 10.02 /spl mu/m gate width. The equivalent oxide thicknesses were: HfO/sub 2/ 23 /spl Aring/, HfAlO/sub x/ 28.5 /spl Aring/ and HfO/sub 2//Al/sub 2/O/sub 3/ 33 /spl Aring/. In addition to the core structures with only about 10 /spl Aring/ of oxide between the high-K dielectric and silicon substrate, there were "double-gate oxide" structures where an interfacial oxide layer of 40 /spl Aring/ was grown between the high-K dielectric and Si. DC analysis showed low gate leakage currents in the order of 10/sup -12/ A(2-5 /spl times/ 10/sup -5/ A/cm/sup 2/) for the devices and, in general, yielded higher threshold voltages and lower mobility values when compared to the corresponding SiO/sub 2/ devices. The unified number-mobility fluctuation model was used to account for the observed 1/f noise and to extract the oxide trap density, which ranged from 1.8 /spl times/ 10/sup 17/ cm/sup -3/ eV/sup -1/ to 1, 3 /spl times/ 10/sup 19/ cm/sup -3/ eV/sup -1/ somewhat higher compared to conventional SiO/sub 2/ MOSFETs with the similar device dimensions. There was no evidence of single electron switching events or random telegraph signals. The aim of this paper is to present a general discussion on low-frequency noise characteristics of the three different high-K/gate stacks, relative comparison among them and to the Si-SiO/sub 2/ system.     

Low-frequency noise in submicrometer MOSFETs with HfO/sub 2/, HfO/sub 2//Al/sub 2/O/sub 3/ and HfAlO/sub x/ gate stacks

Low-frequency noise measurements were performed on p- and n-channel MOSFETs with HfO/sub 2/, HfAlO/sub x/ and HfO/sub 2//Al/sub 2/O/sub 3/ as the gate dielectric materials. The gate length varied from 0.135 to 0.36 /spl mu/m with 10.02 /spl mu/m gate width. The equivalent oxide thicknesses were: HfO/sub 2/ 23 /spl Aring/, HfAlO/sub x/ 28.5 /spl Aring/ and HfO/sub 2//Al/sub 2/O/sub 3/ 33 /spl Aring/. In addition to the core structures with only about 10 /spl Aring/ of oxide between the high-/spl kappa/ dielectric and silicon substrate, there were "double-gate oxide" structures where an interfacial oxide layer of 40 /spl Aring/ was grown between the high-/spl kappa/ dielectric and Si. DC analysis showed low gate leakage currents in the order of 10/sup -12/A(2-5/spl times/10/sup -5/ A/cm/sup 2/) for the devices and, in general, yielded higher threshold voltages and lower mobility values when compared to the corresponding SiO/sub 2/ devices. The unified number-mobility fluctuation model was used to account for the observed 1/f noise and to extract the oxide trap density, which ranged from 1.8/spl times/10/sup 17/ cm/sup -3/eV/sup -1/ to 1.3/spl times/10/sup 19/ cm/sup -3/eV/sup -1/, somewhat higher compared to conventional SiO/sub 2/ MOSFETs with the similar device dimensions. There was no evidence of single electron switching events or random telegraph signals. The aim of this paper is to present a general discussion on low-frequency noise characteristics of the three different high-/spl kappa//gate stacks, relative comparison among them and to the Si--SiO/sub 2/ system.     

Scattering of the TE/sub 01/ and TM/sub 01/ Modes on Transverse Discontinuities in a Rod Dielectric Waveguide-Application to the Dielectric Resonators

Our purpose is to determine the resonance frequency together with the radiation quality factor of dielectric resonators. To do that, the reflection and the scattering properties of the TE/sub 01/ and TM/sub 01/ modes, incident on an abruptly ended dielectric rod, are analyzed. After the building of the complete mode spectrum on each side of the discontinuity, the continuity relations in the discontinuity plane associated with the orthogonality properties lead to a coupled integral equation system. That one is solved by means of an iterative procedure, providing all the characteristics of the discontinuity (reflection or coupling coefficients, radiation losses). Then, these solutions are used to determine the resonant frequency and the radiation quality factor of cylindrical resonators which are considered as waveguide lengths between two interacting discontinuities.     

Work function of Ni silicide phases on HfSiON and SiO/sub 2/: NiSi, Ni/sub 2/Si, Ni/sub 31/Si/sub 12/, and Ni/sub 3/Si fully silicided gates

A complete determination of the effective work functions (WF) of NiSi, Ni/sub 2/Si, Ni/sub 31/Si/sub 12/ and Ni/sub 3/Si on HfSiON and on SiO/sub 2/ is presented. Conditions for formation of fully silicided (FUSI) gates for NiSi/sub 2/, NiSi, Ni/sub 3/Si/sub 2/, Ni/sub 2/Si, Ni/sub 31/Si/sub 12/ and Ni/sub 3/Si crystalline phases were identified. A double thickness series (HfSiON/SiO/sub 2/) was used to extract WF on HfSiON accounting for charge effects. A strong effect on WF of Ni content is observed for HfSiON, with higher WF for the Ni-rich silicides suggesting unpinning of the Fermi level. A mild dependence is observed for SiO/sub 2/. While all Ni-rich silicides have adequate WF for pMOS applications, Ni/sub 2/Si is most attractive due to its low formation temperature, lower volume expansion and ease of integration. Similar threshold voltages (-0.3 V) were obtained on Ni/sub 2/Si and Ni/sub 31/Si/sub 12/ FUSI HfSiON pMOSFETS.     

A High-Capacity Digital Communication System Using TE/sub 01/ Transmission in Circular Waveguide

In this paper, we describe the characteristics and several parts of a high-capacity digital communications system using the low-loss circular waveguide.     

Low-K/Cu CMOS-based SoC technology with 115-GHz f/sub T/, 100-GHz f/sub max/, low noise 80-nm RF CMOS, high-Q MiM capacitor, and spiral Cu inductor

Logic CMOS-based RF technology is introduced for a 10-Gb transceiver in which active and passive RF devices have been realized in a single chip. RF nMOS of 115-GHz f/sub T/, 100-GHz f/sub max/, and sub-1.0-dB NF/sub min/ at 10 GHz have been fabricated by aggressive device scaling and layout optimization. High-Q MiM capacitor and spiral Cu inductors have been successfully implemented in the same chip by 0.13-/spl mu/m low-K/Cu back end of integration line technology. Core 1.0 V MOS and/or junction varactors for VCO at 10 GHz are offerings free of extra cost and realized by the elaborated layout.     

A Compact, Wide-Tuning Range, Dual TE/sub 111/ Mode Preselector

This paper describes the development of a dual TE/sub 111/ mode cavity preselector that is centrally loaded with a large, nonferrous, metallic perturbation plug. The cavity tunes over the 6 to 8 GHz range. Dual mode operation reduces the size of the cavity to one-half the size of a conventional cavity. The perturbing plug increases the separation between the desired TE/sub 111/ mode and the undesired, next higher TM/sub 011/ mode from 15 Percent to 33 Percent. The result is a 29 percent tuning range that is free from unwanted modes. The preselector exhibits a 3 dB bandwidth of 60 MHz, a 40 dB bandwidth of about 400 MHz, and an insertion loss that is no more than 1 dB.     

Cryogenic operation of third-generation, 200-GHz peak-f/sub T/, silicon-germanium heterojunction bipolar transistors

We present a comprehensive investigation of the cryogenic performance of third-generation silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technology. Measurements of the current-voltage (dc), small-signal ac, and broad-band noise characteristics of a 200-GHz SiGe HBT were made at 85 K, 120 K, 150 K, 200 K, and 300 K. These devices show excellent behavior down to 85 K, maintaining reasonable dc ideality, with a peak current gain of 3800, a peak cut-off frequency (f/sub T/) of 260 GHz, a peak f/sub max/ of 310 GHz, and a minimum noise figure (NF/sub min/) of approximately 0.30 dB at a frequency of 14 GHz, in all cases representing significant improvements over their corresponding values at 300 K. These results demonstrate that aggressively scaled SiGe HBTs are inherently well suited for cryogenic electronics applications requiring extreme levels of transistor performance.