Inversion-mode GaInAs MISFET ring oscillators

Inversion mode, self-aligned-gate, metal-insulator-semiconductor field-effect transistors (MISFET's) have been fabricated on p-type Ga0.47In0.53As epitaxially grown on semi-insulating InP substrates. Ring-oscillator (RO) circuits were designed using enhancement-driver/ enhancement-load-type logic gates. Propagation delay as low as 50 ps was measured in a nine-stage ring oscillator (driver MISFET about 1.2-µm gate length) with a fan-in and fan-out of one. These are believed to be the first results on GaInAs inversion-mode MISFET-based digital integrated circuits.     

Wide-band amplifiers for television

The maximum uniform amplification that can be secured over a wide frequency band by means of a single vacuum tube is much greater than that of the usual simple circuits. It can be secured by either of two arrangements, one using an individual filter coupling each tube to the next, and the other using degenerative feedback in each stage to make the stage behave as a section of a confluent filter. In either case, the shunt capacitance on each side of each tube is included in an individual full-shunt arm of a band-pass or low-pass filter. One end of each interstage filter, or of each filter including one or more feedback stages, is extended to a dead-end termination with resistance approximately matching the image impedance. The other end is terminated at one of the tubes in a full-shunt arm, where the filter presents the maximum uniform impedance that can be built up across the tube capacitance. These concepts in terms of wave filters lead to practical wide-band circuits adapted to meet any given requirements. The following general formula is shown to express the maximum uniform amplification that can be secured in one tube: A = gm/πfw√CgCpin which A is the voltage ratio between input and output circuits of equal impedance, gmis the transconductance of the tube, Cgand Cpare the grid and plate capacitance of the tube, and fwis the width of the frequency band.     

Wide-band, low-noise, matched-impedance amplifiers in submicrometer MOS technology

Circuit design techniques for realizing wideband, low-noise, matched-impedance amplifiers in submicrometer MOS technology are discussed. A circuit configuration with two feedback loops has been fabricated in an experimental 1-/spl mu/m NMOS technology. The fabricated amplifier has an insertion gain of 16.35 dB, a -3-dB bandwidth of 758 MHz, a maximum input voltage standing-wave ratio (VSWR) of 2.45, a maximum output VSWR of 1.60, and an average noise figure of 6.7 dB (with reference to a 50-/spl mu/m source resistance) from 10 to 758 MHz.     

Wide-band dynamic modeling of power amplifiers using radial-basis function neural networks

A radial-basis function neural network (RBFNN) has been used for modeling the dynamic nonlinear behavior of an RF power amplifier for third generation. In the model, the signal's envelope is used. The model requires less training than a model using IQ data. Sampled input and output signals were used for identification and validation. Noise-like signals with bandwidths of 4 and 20 MHz were used. The RBFNN is compared to a parallel Hammerstein (PH) model. The two model types have similar performance when no memory is used. For the 4-MHz signal, the RBFNN has better in-band performance, whereas the PH is better out-of-band, when memory is used. For the 20-MHz signal, the models have similar performance in- and out-of-band. Used as a digital-predistortion algorithm, the best RBFNN with memory suppressed the lower (upper) adjacent channel power 7 dB (4 dB) compared to a memoryless nonlinear predistorter and 11 dB (13 dB) compared to the case of no predistortion for the same output power for a 4-MHz-wide signal.     

Wide-band polarization-free wavelength conversion based on four-wave-mixing in semiconductor optical amplifiers

Wide-band polarization free wavelength conversion based on four-wave mixing in semiconductor optical amplifiers (SOAs) subject to two pump beams has been studied in detail. With equalized forward and backward pump power, polarization independence of the converted signal was experimentally achieved when the wavelength detuning was larger than 1.24 nm. This is independent of the SOA bias current. When the wavelength detuning between the signal and one pump beam was fixed at 1.6 nm, the amplitude of the converted signal was nearly constant over a 58-nm wavelength range. A new theoretical analysis allows for signals of arbitrary polarization state to be considered. The experimental results are in good agreement with the theory developed here.     

AlInAs/GaInAs on InP HEMTs for low power supply voltage operation of high power-added efficiency microwave amplifiers

High power-added efficiency microwave power amplifier results are reported for AlInAs/GaInAs on InP HEMTs operated at relatively low power supply voltages (2.5-3 V). C-band power amplifiers are reported with power-added efficiencies as high as 67%, and output powers between 200 and 300 mW. This excellent performance at low power supply voltages is attributed to the high gain and low access resistances of the devices, which leads to a high drain efficiency despite the low power supply voltage.<>     

Wide-band transimpedance amplifiers using AlGaAs/InxGa1-xAs pseudomorphic 2-DEG FET's

Monolithic wide-band amplifiers have been demonstrated using AlGaAs/In_xGa_1-xAs/GaAs pseudomorphic two-dimensional electron-gas field-effect transistors. The amplifiers have yielded an 18.0 GHz bandwidth and a 41.8 dBΩ transimpedance gain with a feedback resistance of 100 Ω. In addition, the dependence of In mole fraction for an In_xGa_1-xAs channel layer on device and amplifier performance has been also investigated. The g_m and the f_T in a device, along with the bandwidth, the gain, and the noise performance in an amplifier, have improved as the In mole fraction is varied from 0 to 0.25     

金刚石 MISFET 器件的研究

Based on the hydrogen-terminated surface channel diamond material,a 1μm gate length diamond metal-insulator-semiconductor field-effect transistor（MISFET） was fabricated.The gate dielectric Al₂O₃ was formed by naturally oxidated thin Al metal layer,and a less than 2 pA gate leakage current was obtained at gate bias between -4 V and 4 V.The DC characteristic of the diamond MISFET showed a drain-current density of 80 mA/mm at drain voltage of -5 V,and a maximum transconductance of 22 mS/mm at gate-source voltage of -3 V.With the small signal measurement,a current gain cutoff frequency of 2.1 GHz was also obtained.     

High I-V product LT-GaAs MISFET structure

Low temperature (LT) GaAs MISFETs with 680 mA/mm drain current and 28 V drain voltage have been fabricated. This represents the highest I-V product of a GaAs FET to date, indicating an RF-power handling capability of 2.1 W/mm. The weak dependence of the breakdown voltage on the doping-thickness product indicates that further improvements are possible.<>     

Structural and compositional control of the output wavelength of very high power 0.98 mu m GaInAs lasers for pumping fiber amplifiers

The authors report on the design, fabrication, and characterization of high-power strained-layer (SL) InGaAs single-quantum-well (SQW) lasers. The lasers emit a 0.980+or-0.002 mu m. They deliver over 100 mW CW optical power at room temperature in a stable single lateral mode with a beam divergence of 15 approximately=20 degrees . The maximum CW output power measured is 265 mW. The lasers have been successfully used as pump sources for an erbium-doped fiber amplifier.<>     

Schottky-barriers on p-type GaInAs

On p-type Ga0.47In0.53As LPE-grown layers, Schottky diodes were fabricated with different metals and surface preparations. On chemically etched surfaces, diodes with ideality factors near unity but rather low breakdown voltages with soft breakdown were achieved. The barrier heights were between 0.4 and 0.7 eV depending on the work function of the metal. On sputter-cleaned surfaces the diodes exhibited high breakdown voltages and barrier heights of about 0.7 eV independent of the metal. Annealing of the diodes at 320°C resulted in reduced series resistances and barrier heights in the case of sputteretched surfaces. The junction seems to consist of two different barriers; the lower one is determined by an As segregation at the interface, whereas the higher one is caused by traps which are induced by the sputter process.     

High-efficiency GaInAs Microwave MISFET's

GaInAs metal-insulator-semiconductor FET's (MISFET's) fabricated with a self-aligned-gate process and 1-µm gate lengths gave power outputs as high as 857 (1.53), 424 (0.76), 415 (0.74), and 114 mW (0.20 W/mm) at 4, 12, 20 and 32.5 GHz, respectively. Power-added efficiencies of 64.3 and 55.0 percent were obtained at 4 and 12 GHz, respectively. At 20 GHz, a power-added efficiency of 32.5 percent was obtained. The value off_{max}calculated from measured scattering parameters (S parameters) was ∼ 45 GHz. This high cutoff frequency was validated by the measured performance at 32.5 GHz. We believe this to be the best microwave performance reported for GaInAs power transistors. A self-aligned-gate process, essential for minimizing gate overlap capacitances while maintaining a full-gate structure, that offers the potential for Submicrometer gate-length device fabrication is described.     

A self-aligned enhancement-mode AlGaAs/InP MISFET

An enhancement-mode insulated-gate field-effect transistor (FET) has been fabricated by a self-aligned technique on semi-insulating InP substrate with an AlGaAs gate barrier grown by molecular beam epitaxy (MBE). A device with a gate length of 1 µm exhibited a transconductance of 134 mS/mm and a threshold voltage of 0.9 V. The characteristics are insensitive to light down to 77 K and hysteresis is completely absent. The performance of this device shows that the fabrication of enhancement-mode devices on severely lattice-mismatched heterostructures is feasible.     

Inversion-mode InP MISFET employing phosphorus-nitride gate insulator

A phosphorus-nitride (P3N5) CVD was newly developed for preparation of a high-quality gate insulator on an InP substrate. This film exhibited ohmic conduction with a breakdown field intensity as high as 1×107 V/cm. An inversion-mode n-channel InP MISFET was fabricated employing the phosphorus-nitride CVD film as a gate insulator. An effective electron mobility of 1000?1640 cm2/Vs was obtained for this device.     

High-speed GaInAs Schottky photodetector

A Schottky contact photodiode on p-type GaInAs for application at ?=1.3?1.6 ?m has been fabricated and tested. The coaxial type device shows an external quantum efficiency of 19% at ?=1.27 ?m, and rise and fall times of less than 15 ps.     

Self-aligned-gate GaInAs microwave MISFET's

A self-aligned-gate GaInAs metal-insulator-semiconductor FET (MISFET) fabrication process that minimizes gate overlap capacitance and offers the potential of achieving submicrometer gate lengths is described. GaInAs MISFETs (1-µm gate length) fabricated with this process have given 0.49-W/mm gate width and corresponding power-added efficiencies of 48 and 39 percent at 4 and 8 GHz, respectively, at a drain voltage of 5.5. V. A small-signal gain of 3.2 dB was obtained at 15 GHz. The estimated carrier velocity was 1.7 × 10⁷cm/s. More recent devices have carrier velocities of 2.5 × 10⁷cm/s and are expected to have improved microwave performance.     

Low-power high-speed InP MISFET direct-coupled FET logic

High-dynamic-range n-channel InP MISFET direct-coupled FET logic ring oscillator and inverter integrated circuits with minimum observed propagation delay per staget_{pd} = 62ps with associated power delay product of 41 fJ and minimum observed power delay productPt_{pd} = 22fJ with associated delay of 84 ps have been fabricated on Fe-doped semi-insulating substrate material using ion implantation for contact and load channel regions and pyrolytic SiO2as the gate insulator. Accumulation-type enhancement-mode MISFET structures with source-drain separations of 1.5 µm and gate metallization lengths of 3.0 µm were employed as driver devices while both MESFET's and 1.5-µm-length ungated "velocity saturation" structures were used as loads. WithV_{DD} = 4.5V representative inverter structures exhibited logic swings of 3.58 V, noise margins of 1.00 and 0.92 V, and dc gain in the linear region of 2.2.     

2-D particle modelling of the InP MISFET

Taking into account two-dimensional effects and non-stationary transport dynamics, InP-MISFETs with submicron gates have been modelled. Contrary to similar Silicon MOSFETs, channel pinch-off rather than velocity limitation is the drain current saturation mechanism. In addition the drain current and the cut-off frequency are approximately 5 times higher in InP. In order to compare the calculated channel mobility to experimental values, also a 2-μm InP MISFET with realistic doping profiles has been modelled. It appears that interface potential well fluctuations arising from surface roughness or random distributed oxide charges are the main mechanism responsible for channel mobility reduction. Owing to the energy dependance of these mechanisms, the potentially high mobility value of III–V MIS devices can be drastically suppressed.     

High-speed monolithic GaInAs pinFET

A monolithic planar structure pin photodiode/field-effect transistor (pinFET) consisting of a low capacitance InP/GaInAs embedded pin photodiode and an AlInAs/GaInAs FET has been developed for long wavelength optical communications. Very high bitrate response capability of over 8 Gbit/s and good receiver performance at 2 Gbit/s have both been demonstrated     

Wide-band orthomode transducers

A summary of the results of a mainly experimental investigation into the development of wideband orthomode transducers (OMTs) is presented. It is shown that satisfactory performance for many applications is possible over bandwidths in excess of 2:1. The wideband return loss and cross-polarization behavior are given where the OMT used is measured in conjunction with a wideband corrugated horn. Two types of OMT are considered: one based on a finline technique and the other on a quad-ridged waveguide geometry. Overall, the latter design gives superior performance