Low-power performance of 0.5-μm JFET for low-cost MMIC's inpersonal communications

The low-power microwave performance of an enhancement-mode ion-implanted GaAs JFET is reported. A 0.5-μm×100-μm E-JFET with a threshold voltage of V_th=0.3 V achieved a maximum DC transconductance of g_m=489 mS/mm at V _ds=1.5 V and I_ds=18 mA. Operating at 0.5 mW of power with V_ds=0.5 V and I_ds =1 mA, the best device on a 3-in wafer achieved a noise figure of 0.8 dB with an associated gain of 9.6 dB measured at 4 GHz. Across a 3-in wafer the average noise figure was F_min=1.2 dB and the average associated gain was G_a=9.8 dB for 15 devices measured. These results demonstrate that the E-JFET is an excellent choice for low-power personal communication applications     

Quarter-micrometer low-noise pseudomorphic GaAs HEMTs withextremely low dependence of the noise figure on drain-sourcecurrent

Quarter-micrometer pseudomorphic (PM) AlGaAs-InGaAs-GaAs HEMTs with an In mole fraction of 21% have been successfully developed, fabricated, and characterized. The devices are realized in a commercial technology by using a multiple-gate-finger layout with air bridges for the interconnection of the source pads and a Si₃N₄ passivation. PM HEMTs with a gate width of 6×20 μm exhibit state-of-the-art noise figures of 0.65 and 0.82 dB with an associated gain of 14.5 and 11.5 dB at 12 and 18 GHz, respectively. The noise figure shows the lowest dependence on the drain-source current yet reported with ΔF_max<0.12 dB for a wide biasing range from 25% I_dss up to 150% I _dss at 12 GHz when I_dss=170-250 mA/mm     

On the design and performance of a 6-18 GHz three-tier matrixamplifier

A 3×3 matrix amplifier for the 6-18-GHz frequency band has been developed. Using MESFETs fabricated on VPE (vapor-phase epitaxial) material, gains of G=23.5±0.5 dB with a maximum reflection loss of RL=-10 dB were obtained from 5.2 to 18.7 GHz. Gain improvement to G=29.1±1.1 dB at a worst-case reflection loss of RL=-7.5 dB between 4.6 and 18.3 GHz when MBE (molecular-beam epitaxial) material was used for the MESFETs. In addition to the experimental results, important design considerations, especially in regard to the termination impedances of the idle ports, are discussed     

W-band low-noise InAlAs/InGaAs lattice-matched HEMTs

Very low-noise 0.15-μm gate-length W-band In_0.52 Al_0.48As/In_0.53Ga_0.47As/In _0.52Al_0.48As/InP lattice-matched HEMTs are discussed. A maximum extrinsic transconductance of 1300 mS/mm has been measured for the device. At 18 GHz, a noise figure of 0.3 dB with an associated gain of 17.2 dB was measured. The device also exhibited a minimum noise figure of 1.4 dB with 6.6-dB associated gain at 93 GHz. A maximum available gain of 12.6 dB at 95 GHz, corresponding to a maximum frequency of oscillation, f_max, of 405 GHz (-6-dB/octave extrapolation) in the device was measured. These are the best device results yet reported. These results clearly demonstrate the potential of the InP-based HEMTs for low-noise applications, at least up to 100 GHz     

94-GHz 0.1-μm T-gate low-noise pseudomorphic InGaAs HEMTs

Fabrication of state-of-the-art W-band 0.1-μm T-gate pseudomorphic (PM) InGaAs high electron mobility transistors (HEMTs) is reported. This device achieved a noise figure of 2.1 dB with an associated gain of 6.3 dB at 93.5 GHz. The device has a maximum gain of 9.6 dB at 94 GHz, which extrapolates to an F_max of 290 GHz. This noise figure is claimed to be the lowest ever reported for HEMTs fabricated on GaAs substrates at this frequency range     

AlInAs-GaInAs HEMT for microwave and millimeter-wave applications

The status of lattice-matched high-electron-mobility transistors (HEMTs) and pseudomorphic AlInAs-GaInAs grown on In substrates is reviewed. The best lattice-matched devices with 0.1-μm gate length had a transconductance g_m=1080 mS/mm and a unity current gain cutoff frequency f_T=178 GHz, whereas similar pseudomorphic HEMTs had g_m=1160 mS/mm and f_T=210 GHz. Single-stage V-band amplifiers demonstrated 1.3- and 1.5-dB noise figures and 9.5- and 8.0-dB associated gains for the lattice-matched and pseudomorphic HEMTs, respectively. The best performance achieved was a minimum noise figure of F_min=0.8 dB with a small-signal gain of G_a=8.7 dB     

A W-band image-rejection downconverter

The design, fabrication, and evaluation of a W-band image-rejection downconverter based on pseudomorphic InGaAs-GaAs HEMT technology are presented. The image-rejection downconverter consists of a monolithic three-stage low-noise amplifier, a monolithic image-rejection mixer, and a hybrid IF 90° coupler with an IF amplifier. The three-stage amplifier has a measured noise figure of 3.5 dB, with an associated small signal gain of 21 dB at 94 GHz while the image-rejection mixer has a measured conversion loss of 11 dB with +10 dBm LO drive at 94.15 GHz. Measured results of the complete image-rejection downconverter including the hybrid IF 90° coupler and a 10 dB gain amplifier show a conversion gain of more than 18 dB and a noise figure of 4.6 dB at 94.45 GHz     

Super-low-noise performance of direct-ion-implanted 0.25-μm-gateGaAs MESFET's

The authors report on advanced ion implantation GaAs MESFET technology using a 0.25-μm `T' gate for super-low-noise microwave and millimeter-wave IC applications. The 0.25×200-μm-gate GaAs MESFETs achieved 0.56-dB noise figure with 13.1-dB associated gain at 50% I_DSS and 0.6 dB noise figure with 16.5-dB associated gain at 100% I_DSS at a measured frequency of 10 GHz. The measured noise figure is comparable to the best noise performance of AlGaAs/GaAs HEMTs and AlGaAs/InGaAs/GaAs pseudomorphic HEMTs     

Half-micrometer gate-length ion-implanted GaAs MESFET with 0.8-dBnoise figure at 16 GHz

Ion-implanted GaAs MESFETs with half-micrometer gate length have been fabricated on 3-in-diameter GaAs substrates. At 16 GHz, a minimum noise figure of 0.8 dB with an associated gain of 6.3 dB has been measured. This noise figure is believed to be the lowest ever reported for 0.5- and 0.25-μm ion-implanted MESFETs, and is comparable to that for 0.25-μm HEMTs at this frequency. By using the Fukui equation and the fitted equivalent circuit model, a K_f factor of 1.4 has been obtained. These results clearly demonstrate the potential of ion-implanted MESFET technology for K-band low-noise integrated circuit applications     

High-performance in W-band monolithic pseudomorphic InGaAsHEMT LNA's and design/analysis methodology

High-performance W-band monolithic one- and two-stage low noise amplifiers (LNAs) based on pseudomorphic InGaAs-GaAs HEMT devices have been developed. The one-stage amplifier has a measured noise figure of 5.1 dB with an associated gain of 7 dB from 92 to 95 GHz, and the two-stage amplifier has a measured small signal gain of 13.3 dB at 94 GHz and 17 dB at 89 GHz with a noise figure of 5.5 dB from 91 to 95 GHz. An eight-stage LNA built by cascading four of these monolithic two-stage LNA chips demonstrates 49 dB gain and 6.5 dB noise figure at 94 GHz. A rigorous analysis procedure was incorporated in the design, including accurate active device modeling and full-wave EM analysis of passive structures. The first pass success of these LNA chip designs indicates the importance of a rigorous design/analysis methodology in millimeter-wave monolithic IC development     

60-GHz noise performance of ion-implanted InxGa1-xAs MESFET's

The authors report the 60-GHz noise performance of low-noise ion-implanted In_xGa_1-xAs MESFETs with 0.25 μm T-shaped gates and amplifiers using these devices. The device noise figure was 2.8 dB with an associated gain of 5.6 dB at 60 GHz. A hybrid two-state amplifier using these ion-implanted In_xGa_1-x As MESFETs achieved a noise figure of 4.6 dB with an associated gain of 10.1 dB at 60 GHz. When this amplifier was biased at 100% I _dss, it achieved 11.5-dB gain at 60 GHz. These results, achieved using low-cost ion-implantation techniques, are the best reported noise figures for ion-implanted MESFETs     

A Si bipolar monolithic RF bandpass amplifier

The application of monolithic inductors to the realization of Si bipolar monolithic RF amplifiers is investigated. As a test vehicle, a bipolar monolithic bandpass amplifier was fabricated and characterized. A 4-nH silicon integrated inductor was used to achieve a peak S ₂₁ gain of 8 dB, a simulated noise figure of 6.4 dB, and a matched input impedance of 50 Ω in the frequency range of 1-2 GHz     

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     

High microwave and ultra-low noise performance of fullyion-implanted GaAs MESFETs with Au/WSiN T-shaped gate

Fully ion-implanted n⁺ self-aligned GaAs MESFETs with high microwave and ultra-low-noise performance have been fabricated. T-shaped gate structures composed of Au/WSiN are employed to reduce gate resistance effectively. A very thin and high-quality channel with high carrier concentration can be formed by adopting the optimum annealing temperature for the channel, and the channel surface suffers almost no damage by using ECR plasma RIE for gate formation. GaAs MESFETs with a gate length as short as 0.35 μm demonstrated a maximum oscillation frequency of 76 GHz. At an operating frequency of 18 GHz, a minimum noise figure of 0.81 dB with an associated gain of 7.7 dB is obtained. A K_f factor of 1.4 estimated by Fukui's noise figure equation, which is comparable to those of AlGaAs/GaAs HEMTs with the same geometry, reveals that the quality of the channel is very high     

Development of highly dense four-stage flat-gain 1-W 6-18-GHz MMICpower amplifier chip

A state-of-the-art dual-channel four-stage MMIC power chip operating over C-X-Ku bands has been produced. The chip, which is only 4.35 mm×5.1 mm, operates over 6-17 GHz with very small gain ripple. At 25°C each one of its channels provides 29.5±0.5 dBm at 2-dB compression (2 dBc) from a small-signal gain of 19.5±1.5 dB. The drain bias is 7 V. and the power added efficiency is 11-14%. At 85°C, power and gain decrease by 0.5-1 and 3.5-4 dB, respectively. The design was iterated once to produce an all-monolithic amplifier chip that operates over the full 6-18-GHz frequency band and provides more than 1 W at 18 GHz. The architecture and size were maintained in the iterated design. The excellent power and gain ripple performances of the C-X-Ku chip extended to 18 GHz with a small-signal gain reduction of 0.5-1 dB. The chip is designed for use with inputs and outputs coupled externally for additional 2-2.5 dB of power. Excellent performance over 6-18 GHz was achieved using Lange couplers on 10-mil alumina     

Noise caused by semiconductor lasers in high-speed fiber-opticlinks

Theoretical and experimental results are presented for the signal-to-noise (S/N) ratio caused by mode partition noise, intensity noise, and reflection-induced noise in optical data links. Under given conditions an additional noise source with a S /N ratio of 20 dB will cause a power penalty of 1 dB in order to maintain a 10^-9 bit error rate. From numerical simulations the authors predict the maximum allowable dispersion in the presence of mode partition noise to be approximately 40% of a clock period. This figure is almost independent of bit rate and laser structure and agrees well with the measurements and with results of other workers. Numerical simulations of a buried-heterostructure and a TJS laser were carried out at four bit rates from 565 Mbit/s to 4.5 Gbit/s and the measurements were done at 2.2 Gbit/s using a TJS laser     

60-GHz pseudomorphic-MODFET low-noise MMIC amplifiers

The development of V-band low-noise monolithic microwave integrated circuits (MMICs) based on pseudomorphic modulation-doped FETs (P-MODFETs) is presented. These dual-stage MMICs incorporate P-MODFETs, with 0.35-μm×60-μm gates, as the active elements, electron-beam-written tuning elements, and DC-blocking and bias networks. The dual-stage chips exhibited a maximum gain of 10.2 dB at 59.5 GHz and a minimum noise figure of 5.3 dB, with an associated gain of 8.2 dB at 58.2 GHz. A cascaded four-stage amplifier using two MMIC modules exhibited 5.8-dB minimum noise figure with an associated gain of 18.3 dB at 58 GHz and up to 21.1 dB of maximum gain     

Backscatter and attenuation by falling snow and rain at 96, 140,and 225 GHz

The results of measurements are presented for backscatter cross section per unit volume and attenuation for falling snow and rain at 96, 140, and 225 GHz. The attenuation due to rain is almost independent of the measurement frequency, but for snow the attenuation is considerably greater at 225 GHz than at 96 GHz. The rain attenuation generally varies with the rain accumulation rate in accordance with an aR^b relationship for a Laws and Parsons drop-size distribution where R is the rain rate and a and b are constants. The attenuation at all three frequencies is about 3 dB/km for a rain rate of 4 mm/h. The attenuation due to snow varies with airborne snow-mass concentration, with the average rates of increase being 0.9, 2.5, and 8.7 (dB/km)(g/m³) at 96, 140, and 225 GHz, respectively. Generally the attenuation for snow is lower than that for rain. The backscatter cross section per unit volume for rain at 96 GHz is about -35 dB m²/m³ for a rain rate of 4 mm/h. The backscatter from snow at 96 GHz is much lower than that from rain under equivalent accumulation rates or airborne mass concentrations. Snow backscatter at 140 GHz is comparable but higher than that at 96 GHz     

A low-loss bandpass filter using electrically coupled high-Q TM01δ dielectric rod resonators

For a TM_01δ mode dielectric rod resonator placed coaxially in a TM₀₁ cutoff circular waveguide, characteristics such as the resonant frequency, its temperature coefficient, the unloaded Q, and the other resonances are discussed on the bases of accurate calculations using the mode-matching method. The results show that this resonator compares favorably with a conventional TE_01δ mode dielectric resonator, particularly for realization of a high unloaded Q. Analytical results also verify that interresonator coupling between these two resonators can be expressed equivalently by a capacitively coupled LC resonant circuit. A four-stage Chebyshev filter having a ripple of 0.035 dB and an equiripple bandwidth of 27 MHz at a center frequency of 11.958 GHz was fabricated using these resonators. Its insertion loss is 0.5 dB, which corresponds to an unloaded Q of 17000, and no spurious response appears in the frequency range below 17 GHz     

Noise performance at cryogenic temperatures at AlGaAs/InGaAs HEMT'swith 0.15-μm T-shaped WSix gates

T-shaped 0.15-μm WSi_x gate HEMTs have been fabricated on AlGaAs/InGaAs MBE wafers. Their S-parameters, output noise spectral density P_no, and noise temperatures T _e at cryogenic temperatures, were measured. The current gain cutoff frequency f_T increases from 61 GHz at 295 K to 87 GHz at 90 K. P_no and T_e measurements indicate that the hot-electron effect is noticeable at low temperatures at high drain current. At 30 GHz, the noise temperature is 19±3 K with an associated gain of 10.4 dB at the physical temperature of 20 K. The results demonstrate the great potential of AlGaAs/InGaAs HEMTs for low-temperature applications