Artificially integrated synthetic rectangular waveguide

A synthetic rectangular waveguide (SRW), which consists of two electrical sidewalls and two parallel periodical structures placed at the top and bottom surfaces of the waveguide, is presented. The SRW is made by multilayered integrated circuit processes, which typically have large ratios of SRW lateral dimensions to substrate thickness. Two theoretical methods, finite-element method and deembedding of composite structure consisting of SRW and mode converters, are applied to investigate the propagation characteristics of the SRW. Application of the dispersion characteristics of the two-dimensional periodical structures coupled with appropriate mode converter designs leads to results in SRW designs supporting TE/sub 10/, TM/sub 00/, and TM/sub 10/ modes. Measurements and the two theoretical approaches indicate that the slow-wave factor is 4.9 and Q-factor is 260 at 6.85 GHz for the TE/sub 10/ mode propagation with a cutoff frequency of 4.10 GHz (0.348 factor of cutoff frequency of conventional rectangular waveguide using the same material and dimensions). The theoretical data show the TM/sub 00/ mode to have a slow-wave factor of 1.8, Q-factor of 187.6 at 11.4 GHz, and cutoff frequency of 10.2 GHz. The TM/sub 10/ mode has a slow-wave factor of 1.98, Q-factor of 187.6 at 12.5 GHz, and cutoff frequency of 10.4 GHz.     

Wide Band Metallic Waveguide With In-Line Dielectric Rods

Conventional rectangular metallic waveguides are seldom used at frequencies higher than twice the cutoff frequency because of higher mode propagation. Single-mode propagation is available for a metallic waveguide with arrayed dielectric rods at the center of the waveguide in the frequency under twice the cutoff frequency region using the TE₂₀ mode, and in the frequency over twice the cutoff frequency region using the TE2o mode. If the metallic waveguide and dielectric loss tangent are assumed to be WR-90 (f_c ap6.55 GHz) and 3times10^-4, respectively, then the attenuation constants are smaller than 0.25 dB/m in the frequency range from 7 to 10 GHz, 15 to 16.5 GHz, and from 17.2 to 21 GHz.     

Dual mode wideband band-pass filter with notched band for communication system

This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz. The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at ?? =90° and ?? =0°, respectively. A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity. By using a parallel-coupled feed line, a narrow notched band is introduced at the required frequency and its Fractional BandWidth (FBW) is about 5%. The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic, the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz (calculated from 1.959 GHz with ?34.43 dB to 2.065 GHz with ?2.93 dB) and 228.10 dB/GHz (calculated from 3.395 GHz with ?2.873 dB to 3.507 GHz with ?28.42 dB). This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz. Having been presented in this article, the measurement results agree well with the simulation results, which validates our idea.     

Input impedance of a coaxial line probe feeding a circularwaveguide in the TM01 mode

By means of the conversion of complex power technique (CCPT), a formally exact full-wave solution is given for the case of a coaxial line probe fending a circular waveguide for TM₀₁ modal excitation. The overall scattering matrix of the coaxial-line-prove-circular-waveguide system is deduced. Numerical results for the impedance as `seen' by the coaxial line are presented and compared with experimental results obtained in the 9.0-11.5-GHz frequency range. Their agreement is reasonably good except at the lower frequencies (<10.0 GHz), where the TM₀₁ mode in the circular guide is close to its cutoff frequency (8.14 GHz)     

0.1 THz rectangular waveguide on GaAs semi-insulating substrate

The realisation of a millimetre-wave rectangular waveguide fabricated using traditional monolithic technology is presented. The rectangular waveguide has a cutoff frequency of 100 GHz and an operating frequency of 105 GHz. The measured performance clearly shows that the dominant TE₁₀ mode of propagation is supported     

Microwave performance of a self-aligned GaInP/GaAs heterojunctionbipolar transistor

The microwave performance of a self-aligned GaInP/GaAs heterojunction bipolar transistor (HBT) is presented. At an operating current density of 2.08×10⁴ A/cm², the measured cutoff frequency is 50 GHz and the maximum oscillation frequency extrapolated from measured unilateral gain and the maximum available gain are 116 and 81 GHz, respectively, all using 20-dB/decade slopes. These results are compared with other reported high-frequency performances of GaInP HBTs. In addition, these results are compared with AlGaAs/GaAs HBTs having a similar device structure     

A high cutoff frequency planar Schottky diode with a stripe geometry junction

Design and experimental results of a planar Schottky-barrier diode suitable for use in MIC's are presented. The Schottky junction has a stripe geometry with a closely located ohmic contact. This geometry is effective in reducing the skin-effect parasitic resistance to yield a high cutoff frequency. The experimental diode has been fabricated using n and n⁺GaAs layers selectively grown on a semi-insulating substrate. A zero-bias cutoff frequency of more than 700 GHz has been obtained.     

Over 20-GHz cutoff frequency submicrometer-gate diamond MISFETs

Submicrometer-gate (0.2-0.5-/spl mu/m) diamond metal-insulator-semiconductor field-effect transistors (MISFETs) were fabricated on an H-terminated diamond surface. The maximum transconductance in dc mode reaches 165 mS/mm, while the average transconductance is 70 mS/mm in submicrometer-gate diamond MISFETs. The highest cutoff frequency of 23 GHz and the maximum frequency of oscillation of 25 GHz are realized in the 0.2-/spl mu/m-gate diamond MISFET. From the intrinsic transconductances or the cutoff frequencies, the saturation velocities are estimated to be 4/spl times/10/sup 6/ cm/s in the submicrometer-gate FETs. They are reduced by gate-drain capacitance and source resistance.     

Linearly polarised radial stub fed high performance wideband slotantenna

A wideband printed slot antenna fed by a radial stub operating over the mobile communication bands PCN (1.716-1.880 GHz) and UMTS (1.9-2.0 GHz and 2.1-2.2 GHz) is presented. The impedance bandwidth of the antenna achieved for a VSMR⩽2 is 34% and the radiation patterns remain stable over the entire frequency band of operation (1.7-2.4 GHz) with cross-polarisation levels of less than -20 dB. Simulated and measured radiation pattern and return loss results are presented     

Hot-electron InGaAs/InP heterostructure bipolar transistors withfT of 110 GHz

A hot-electron InGaAs/InP heterostructure bipolar transistor (HBT) is discussed. A unity-current-gain cutoff frequency of 110 GHz and a maximum frequency of oscillation of 58 GHz are realized in transistors with 3.2×3.2-μm² emitter size. Nonequilibrium electron transport, with an average electron velocity approaching 4×10⁷ cm/s through the thin (650 Å) heavily doped (p=5×10¹⁹ cm^-3) InGaAs base and 3000-Å-wide collector space-charge region, results in a transit delay of 0.5 ps corresponding to an intrinsic cutoff frequency of 318 GHz     

基于MMIC工艺的片上射频LC无源滤波器

设计、制作了几种基于MMIC工艺的片上LC低通/带通滤波器并进行了测试. 测试结果表明,一个3nH的MMIC电感在6.8GHz下品质因数达到13.8,自谐振频率达到15.5GHz;制作的LC低通/带通滤波器的截止频率或中心频率与设计偏差很小,分别为2%和3.3%;低通滤波器在各自通带内的插入损耗小于3dB,带通滤波器在中心频率的插入损耗为7.2dB.     

Mode Conversion in Tapered Waveguides At and Near Cutoff

The coupling coefficient between the TE/sub 11/ mode and the TM/sub 11/ mode in tapered circular waveguides is derived, and at cutoff frequency it tends to approach an infinity of the order of 0/sup -1/4/. It is surprising to discover that the corresponding coupling coefficient between the TE/sub 10/ mode and the TM/sub 12/ mode in tapered rectangular waveguides approaches instead a zero of the order of 0/sup 1/4/ at cutoff frequency. Accordingly, for the modes concerned, the choice of using circular or square waveguides as tapers for transition at and near cutoff frequency is significant in reducing mode conversion level. At and near cutoff frequency a "synthesized" square taper is better in that it is shorter than a "synthesized" circular taper for the same mode conversion levels. On the other hand, for frequencies far away from cutoff the choice is insignificant. Design procedures for "synthesized" waveguide tapers at and near cutoff are presented, and the results of measurements are in agreement with the theoretical calculations.     

Enhanced dominant mode operation of a shielded multilayer coplanarwaveguide via substrate compensation

The cutoff frequency of the first higher-order even mode in a shielded multilayer coplanar waveguide (CPW) is studied using the spectral domain approach (SDA). The effective dielectric constant for the dominant odd and first higher-order even mode in a shielded multilayer CPW is computed and compared to other published numerical results. Dielectric constant and substrate height are varied with respect to even mode cutoff frequency and plotted for several CPW structures. Different combinations of internal substrates are shown to produce even mode cutoff frequency maximization for increased odd mode operation bandwidth     

High-speed InGaAsP/InP multiple quantum well, 1.55 mu m singlemode modulator

1.55 mu m single mode ridge waveguide modulators based on electroabsorption in InGaAsP/InP multiple quantum wells (MQW) are reported. A 10 dB extinction ratio was obtained by applying a 2 V drive voltage to a 100 mu m long device with a 3 dB on-state loss. The 3 dB cutoff frequency is 12.5 GHz.<>     

Microwave power double-heterojunction HEMT's

The RF and dc characteristics of microwave power double-heterojunction HEMt's (DH-HEMT's) with low doping density have been studied. Small-signal RF measurements indicated that the cutoff frequency and the maximum frequency of oscillation in DH-HEMT's with 0.8-1 µm gate length and 1.2 mm gate periphery are typically 11- 16 GHz and 36-41 GHz, respectively. However, the cutoff frequency in DH-HEMT's degrades strongly with increasing drain bias voltage. This may be caused by both effects of increasing effective transit length of electrons and decreasing average electron velocity, due to Gunn domain formation. In large-signal microwave measurement, the DH-HEMT (2.4 mm gate periphery) delivered a maximum output power of 1.05 W with 2.8 dB gain and 0.58 W with 1.6 dB gain at 20 and 30 GHz, respectively. These are the highest output powers yet reported for HEMT devices. For the dc characteristics, the onset of two-terminal gate breakdown voltage is found to correlate with the drain current Idssand recessed length, and three-terminal source-drain breakdown characteristics near pinchoff are limited by the gate-drain breakdown. A simple model on gate breakdown voltage in HEMT is also presented.     

A high-gain, low-noise 1/2-μm pulse-doped pseudomorphic HEMT

A 1/2-μm gate-length pulse-doped pseudomorphic high-electron-mobility transistor (HEMT) grown by MBE, which exhibits a current-gain cutoff frequency of 62 GHz, is discussed. The maximum available gain cutoff frequency was greater than 150 GHz. A minimum noise figure of 0.85 dB and associated gain of 14 dB were measured at 10 GHz. Tuned small-signal gain in a waveguide-to-microstrip test fixture at 44 GHz was 7.6 dB. When the HEMT was tuned for power, 260 mW/mm with 5-dB gain and 17% power-added efficiency were obtained at 44 GHz. These results suggest that a 1/2-μm pseudomorphic HEMT is a viable candidate for Q-band applications     

Quasi-static design technique for MM-wave micromachined filterswith lumped elements and series stubs

This paper describes micromachined, membrane-supported low-pass and bandpass filters which are suitable for microwave and millimeter-wave (MM-wave) application. The designs are realized in coplanar-waveguide (CPW) form using short- and open-end series stubs with integrated metal-insulator-metal (MIM) capacitors, and are compact in lateral and longitudinal dimensions. A computationally efficient analysis has been developed for the design and characterization of the filters. The technique is based on a quasi-static coupled-line (CL) treatment of the series stubs, and uses normal mode impedance parameters, which are calculated with the spectral-domain approach (SDA). Due to the broad TEM-bandwidth of the membrane-supported transmission lines, the method can accurately predict filter responses well into the rejection band. To demonstrate the above claims, the measured and simulated S-parameters of a 0.3 mm ×2.2 mm low-pass filter with a cutoff frequency at 17 GHz, and a second passband at 115 GHz, are presented. The new approach is also used in the design of bandpass filters which exhibit 1.5-2-dB insertion loss and bandwidths around 10%     

DC-92 GHz ultra-broadband high gain InP HEMT amplifier with 410 GHzgain-bandwidth product

A coplanar distributed amplifier, fabricated in a double channel InP HEMT technology, is presented. It exhibits a 13 dB gain and a 92 GHz -3 dB cutoff frequency that corresponds to a gain-bandwidth product of 410 GHz. Key aspects for distributed and coplanar design around 100 GHz are highlighted     

Calculations of cutoff frequency, breakdown voltage, and capacitance for diffused junctions in thin epitaxial silicon layers

Recent developments in high-quality silicon varactors for low-noise parametric amplifiers and high-efficiency harmonic generators necessitate the use of epitaxial silicon layers that are thinner than 10 microns, with resistivity less than 1 Ω-cm. This paper extends Breitschwerdt's recent calculations [1] to such thin epitaxial layers, and also includes the calculation of series resistance and capacitance per unit area in a range useful for microwave diode design. A planar geometry for the junction has been assumed. The impurity distribution of the in-diffusion from the surface and the out-diffusion from the substrate are assumed to be complementary error functions. Depletion layer characteristics of the p-n junction-- including junction depth, impurity gradient at the junction, depletion layer width, capacitance per unit area, and avalanche breakdown voltage--are predicted for various epitaxial layer resistivities. The capacitance per unit area at breakdown is also presented in graphical form. Series resistance has been obtained by numerical integration of various impurity distributions. Zero-bias cutoff frequency for various layer thicknesses is presented graphically as a function of junction depth and breakdown voltage. The calculations predict that there are optimum diffusion conditions for maximum cutoff frequency and for maximum breakdown voltage with a given epitaxial layer thickness. They indicate that the optimum zero-bias cutoff frequency is nearly inversely proportional to the thickness of the epitaxial layer. For instance, the maximum cutoff frequency of a junction in a 2-µ layer can exceed 600 GHz compared with 300 GHz in a 4-µ layer, and 140 GHz in an 8-µ layer. Calculated and experimentally determined characteristics show reasonably good agreement.     

Analysis on high-frequency characteristics of SOI lateral BJTs withself-aligned external base for 2-GHz RF applications

High-frequency characteristics of SOI lateral BJTs designed for 2-GHz radio frequency (RF) applications are measured and compared for various link-base length, emitter width, and collector structure. Based on experimental data and device simulation, degradation mechanism of cutoff frequency for shorter link-base is analyzed. By suppressing external base-induced effects, peak cutoff frequency is increased from 10 GHz to 15 GHz