Technology, circuit design and applications of GaAs MMICs

Gallium arsenide monolithic microwave integrated circuits (GaAs MMICs) are a means of utilising the high-mobility, high-frequency aspects of the GaAs MESFET together with the semi-insulating properties of gallium arsenide to form a low-loss integrated circuit with active elements. Novel semiconductor growth structures allow devices with cut-off frequencies well into the millimetre wave ranges to be fabricated, with dramatic improvements in gain and noise figure. Multilevel structures also permit very high circuit densities, so complete receivers and phased-array radar multifunction circuits can be made with high repeatability in a few square millimetres. The authors discuss various aspects of the production process including process control and reliability. The materials used for GaAs MMICs and the fabrication technology used are discussed as are their applications. Future MMIC technology developments are also discussed     

Multifunction SAG process for high-yield, low-cost GaAs microwaveintegrated circuits

A new fully planar, multifunction refractory self-aligned gate (MSAG) technology suitable for the fabrication of GaAs small-signal and power microwave monolithic integrated circuits (MMICs) is demonstrated in a manufacturing environment. Data on the distribution of DC and RF performance and yield for pilot production of discrete FETs and MMICs are presented. The heart of the MSAG process is a planar, self-aligned gate FET. It uses a refractory TiWN Schottky gate and exhibits high performance for small-signal microwave, power microwave, and digital circuit applications. Lots with good wafer yields have demonstrated average chip yields on PCM good wafers of 45%, 49%, and 36% for 2-10-GHz distributed amplifiers, 1-W C-band power amplifiers, and 4-W power amplifiers, respectively     

Divider and combiner line-unified FET's as basic circuit functionmodules. I

The purpose is to realize miniaturized and broadband function blocks with very simple configurations for multifunction monolithic microwave circuits. FET-sized combiners and dividers, in phase and out of phase, based on a novel line-unified-FET (LUFET) concept are described and demonstrated. Some effective extensions such as extended combiner LUFETs, magic T LUFETs, and phase inverter LUFETs are also described. The extension of the basic combiner and divider LUFETs allows the realization of various circuit functions in a very small area. The area of fabricated LUFETs is between 0.1 and 0.3 mm², and the operating frequency bandwidth approaches 20 GHz. The LUFET mitigates the size and complexity problems considerably and expands the application of combiners and dividers to various multifunction microwave monolithic integrated circuits (MMICs)     

Multifunction wide-band array design

High-performance active arrays operating over C, X, and Ku-band have been demonstrated using newly developed designs of wide-band radiating elements and wide-band monolithic microwave integrated circuits (MMICs). The advanced shared aperture program (ASAP) explored the development of wide-band multifunction arrays capable of simultaneous and time interleaved radar, electronic warfare, and communications functions. Two iterations of radiating element and transmit/receive (T/R) module design were completed during this program. The radiating aperture design approach, overall array concepts, and current design technology and performance are summarized     

Design and performance of low-current GaAs MMICs forL-band front-end applications

GaAs monolithic microwave integrated circuits (MMICs) with very low current and of very small size have been developed for L-band front-end applications. The MMICs fully employ lumped LC elements with uniplanar configurations. There are two kinds of MMICs: a low-noise amplifier and a mixer. The low-noise amplifier has a noise figure of 2.5 dB and a gain of 11.5 dB. The mixer has a conversion gain of 12.5 dB small local oscillator (LO) power of -3 dBm. Total current dissipation of the two MMICs is less than 8 mA with 3-V drain bias voltages     

A new meshing criterion for the equivalent thermal analysis of GaAs PHEMT MMICs

In this paper, a new meshing criterion for the equivalent thermal analysis of GaAs PHEMT MMICs (Monolithic microwave integrated circuit) is proposed. Based on the meshing criterion, an equivalent thermal model of GaAs PHEMTs with remarkably reduced mesh complexity is established, and the simplification of both layout pattern and vias of MMICs are performed. Theoretical analysis is applied for the calibration of the equivalent thermal model. Assisted by the meshing criterion, chip-level simulators are capable to obtain the peak temperature of MMICs without using averaging approximations, and achieve considerably high simulation accuracy. As examples, two MMIC power amplifiers are designed and implemented using GaAs PHEMT process. Thermal simulation and measurement results obtained with ANSYS ICEPAK and infrared thermography, respectively, show high consistency. The proposed meshing criterion can be applied to improve the accuracy of thermal analysis of MMICs, and the obtained precise peak temperature can be used to effectively assess the power threshold of the designed amplifiers in reliability tests.     

Multifunction silicon MMIC's for frequency conversion applications

The application of advanced silicon bipolar IC technology to multifunction microwave monolithic integrated circuits (MMICs) is demonstrated. The modeling, design, and testing of two silicon MMICs for frequency conversion applications are illustrated. The first product is a wideband frequency doubler with conversion gain, 20-dBc rejection of harmonics, and a 2-GHz bandwidth. The second product is a wideband vector demodulator (or image reject mixer) that utilizes an onchip digital frequency divider to generate 0° and 90° local oscillator (LO) phases from 0.05 to 1.5 GHz. Both products operate from a single 5-V supply, are load insensitive, require no external baluns, and are packaged in 180-mil hermetic packages. These frequency conversion MMICs and others currently under development have been prototyped on the analog silicon transistor array starCHIP-1, which is also described     

Designing gallium nitride-based monolithic microwave integrated circuits for the Ka, <Emphasis Type="Italic">V</Emphasis>, and <Emphasis Type="Italic">W</Emphasis> bands

A technology for fabricating multifunction monolithic microwave integrated circuits (MMICs) based on gallium nitride (GaN) heterostructures, which operate at the frequency range up to 100 GHz (the Ka, V, and W bands), is developed. Power amplifier (PA) MMICs operating at 90 GHz are fabricated using the coplanar technology with the gain coefficient being up to 15 dB and the specific output power exceeding 500 mW/mm. In addition, microstrip technology with the use of the polymer dielectric and grounding metallization over the wafer surface without through holes in the substrate is approved. The parameters of the MMICs for multifunction single-chip transmit-receive modules (TRMs), as well as the parameters of the MMICs for intermediate-frequency amplifiers (IFAs), voltage-controlled oscillators (VCOs), low noise amplifiers (LNAs), PAs, and balanced mixers operating in the Ka and V bands (up to 70 GHz), which are fabricated using the proposed technology, are presented.     

Total dose and transient radiation effects on GaAs MMICs

To elucidate the effects of radiation on GaAs monolithic microwave integrated circuits (MMICs), radiation-induced changes in DC parameters of test FETs and in the measured microwave performance of MMICs were compared. Changes in material parameters determined from the DC results were used to model the observed microwave performance degradation. In addition, the effect of accumulated radiation damage in MMICs was studied in terms of the amplifier response to transient radiation pulses. The effect of 1-MeV electron irradiation on microwave response and transient radiation pulse response was measured in 0.5- to 12.5-GHz distributed amplifiers (ion-implanted) and in 28-GHz power amplifiers (with epitaxially grown active layers)     

GaAs MMICs offer space and cost reductions for handheld telephones

The use of GaAs monolithic microwave integrated circuits (MMICs) for the power amplifier in portable telephones is a quantum leap in terms of technology and it affords major benefits in return especially for handheld applications. Mitsubishi has led the way in the use of MMICs and of the four current suppliers of handheld analogue telephones to the NTT telecom body in Japan, Mitsubishi is the only company using GaAs MMICs for the power amplifier in its telephones, of which it is currently producing 20 000 to 30 000 per month.     

Accurate characterization and modeling of transmission lines forGaAs MMICs

The authors discuss computer-aided design (CAD) tools together with high-accuracy microwave measurements to realize improved design data for GaAs monolithic microwave integrated circuits (MMICs). In particular, a combined theoretical and experimental approach to the generation of an accurate design database for transmission lines on GaAs MMICs is presented. The theoretical approach is based on an improved transmission-line theory which is part of the spectral-domain hybrid-mode computer program MCLINE. The benefit of this approach in the design of multidielectric-media transmission lines is described. The program was designed to include loss mechanisms in all dielectric layers and to include conductor and surface roughness loss contributions. As an example, using GaAs ring resonator techniques covering 2 to 24 GHz, accuracies in effective dielectric constant and loss of 1% and 15% respectively, are presented. By combining theoretical and experimental techniques, a generalized MMIC microstrip design database is outlined     

Power-amplifier modules covering 70-113 GHz using MMICs

A set of W-band power amplifier (PA) modules using monolithic microwave integrated circuits (MMICs) have been developed for the local oscillators of the far-infrared and sub-millimeter telescope (FIRST). The MMIC PA chips include three driver and three PAs, designed using microstrip lines, and another two smaller driver amplifiers using coplanar waveguides, covering the entire W-band. The highest frequency PA, which covers 100-113 GHz, has a peak power of greater than 250 mW (25 dBm) at 105 GHz, which is the best output power performance for a monolithic amplifier above 100 GHz to date. These monolithic PA chips are fabricated using 0.1-μm AlGaAs/InGaAs/GaAs pseudomorphic T-gate power high electron-mobility transistors on a 2-mil GaAs substrate. The module assembly and testing, together with the system applications, is also addressed in this paper     

Intermixing optical and microwave signals in GaAs microstripcircuits for phase-locking applications

The microwave modulation of the interference generated by optical beams that are reflected from the top and bottom surfaces of GaAs substrate adjacent to a microstrip line is studied. The detected modulation is used to directly characterize the electrooptic effect. This optical-microwave intermixing technique is applied to phase-lock a free-running microwave oscillator with picosecond laser pulses. One potential application of this technique is for the optical on-wafer characterization of MMICs (monolithic microwave integrated circuits)     

Thermal modeling of power gallium arsenide microwave integratedcircuits

Manufacturers are developing power devices for ever higher frequencies using GaAs MESFETs and heterojunction bipolar devices constructed with III-V compounds on GaAs substrates, as well as integrated power devices on monolithic microwave integrated circuits (MMICs). A problem with the technology is the low thermal conductivity of gallium arsenide, giving rise to thermal design problems that must be solved if good reliability is to be achieved. A three-dimensional numerical simulator is used to study this problem. In particular, the approximations which are possible in performing realistic assessments of the thermal resistance of typical GaAs power device structures under steady-state conditions are examined     

Small H-shaped antennas for MMIC applications

A small short-circuited H-shaped GaAs monolithic microwave integrated circuits (MMICs) patch antenna is presented. Resonant at 5.98 GHz, it is the lowest frequency MMIC patch antenna reported that we are aware of and is intended for short-range communications (e.g., vehicular). Initial experimental and theoretical characterization of the proposed structure has been carried out on soft microstrip substrates. It has been shown that the size of an H-shaped patch antenna can be reduced to as low as one tenth of that of a half wavelength patch antenna resonant at the same frequency, saving valuable substrate space. The resonance frequency, radiation patterns and gain have been investigated. Ground plane truncation effects, which are important for MMIC applications, have been examined using the finite-difference time-domain (FDTD) method     

Selective electroless plating-A new technique for GaAs MMICs

A simple, cost-effective processing technique, selective electroless plating, is proposed for GaAs monolithic microwave integrated circuits (MMICs). Microwave measurements show that the attenuation properties of transmission lines fabricated by this processing technique are comparable to the attenuation properties of lines fabricated by the traditional evaporation lift-off technique     

A minaturized broad-band MMIC frequency doubler

A miniaturized broadband balanced MMIC (monolithic microwave integrated circuit) frequency double, composed of a common-gate FET and a common-source FET directly connected to each drain electrode, has been proposed and demonstrated. The doubler is designed and fabricated as a miniaturized function module using a conventional two-gate FET configuration, active trapping, and active impedance matching. The doubler design has been performed through phase error estimation, gate width optimization, and gate-source voltage optimization. The phase error estimation in a nonlinear condition has eliminated phase error compensation circuits. The fabricated chip size is only 0.5 mm×0.5 mm, which is about 1/10 the area of previously reported doublers. A conversion loss of 8-10 dB, a fundamental frequency suppression better than 17 dB, and an input return loss better than 8 dB are obtained in the output frequency range from 6 to 16 GHz. The broadband doubler as a miniaturized MMIC function module can be applicable to small-size oscillator MMICs and multifunction MMICs     

Development of 60-GHz front-end circuits for a high-data-rate communication system

Recent results from a Swedish program for development of 60-GHz monolithic microwave integrated circuits (MMICs) for high-data-rate communication links are presented. Front-end circuits such as mixers, amplifiers, frequency multipliers, IF amplifiers with gain control, and voltage-controlled oscillators (VCOs) have been realized utilizing GaAs PHEMT and MHEMT technologies. A newly developed 7.5-GHz coupled Colpitt VCO shows a minimum phase noise of -95 dBc at 100 kHz offset. A second-harmonic 14-GHz VCO shows a minimum phase noise of less than -90 dBc at 100 kHz. A novel balanced 7-28-GHz MMIC frequency quadrupler is described and compared with a single-ended quadrupler at the same input frequencies. To demonstrate its feasibility and potential application, the quadrupler is combined with the Colpitt VCO and the output characteristics of the resulting 30-GHz MMIC source are measured. A three-stage MHEMT wide-band amplifier covering 43-64 GHz with a gain of 24 dB, a minimum noise figure of 2.5 dB, and a passband ripple of 2 dB is also described. In future 60-GHz systems for mass markets where cost is of utmost importance, Si-based technologies, especially CMOS, are highly interesting. Some recent circuit results based on a 90-nm CMOS technology are also reported.     

Design and performance of wideband GaAs MMIC's for high-speedoptical communication systems

Advanced design techniques for GaAs wideband direct-coupled amplifiers are described. The amplifier achieved a 20 dB gain with a 3 dB bandwidth of 13 GHz and a 5-7 dB noise figure. An equalizing amplifier module consisting of amplifier and variable attenuator monolithic microwave integrated circuits (MMICs) exhibited a high gain of 43 dB over a 10 GHz band with a controllable gain of 20-43 dB     

The fabrication of thin-film bulk acoustic wave resonatorsemploying a ZnO/Si composite diaphragm structure using porous siliconlayer etching

Thin-film bulk acoustic wave resonators (FBARs) are used in monolithic microwave integrated circuits (MMICs) for semiconductor devices. FBARs are more attractive than surface acoustic wave resonators since they have the advantages of small size, low cost, and mass-production ability. In this letter, an FBAR with an air gap is fabricated by a surface micromachining technique which utilizes porous silicon layer (PSL) etching. This FBAR has a forward reflection coefficient of -18.912 dB when the thickness of the ZnO thin film measures 1 μm. The FBAR is composed of a piezoelectric zinc oxide (ZnO) thin film and top and bottom electrode thin films of Au(1000 Å)/Ni-Cr(50 Å). The ZnO thin film is deposited by RF magnetron sputtering. This fabrication process is compatible with conventional IC processes, thereby enabling the development of monolithic-integrated FBAR's on Si or GaAs substrates