Teaches practical ADS skills in creating schematics and EM simulations, drawing and generating layouts, and verifying microwave circuit design Clearly and concisely presents the basic design concepts needed for active microwave circuit design Presents example-rich coverage of a wide spectrum of practical active microwave circuits, including LNAs, PAs, microwave oscillators, and mixers Fills a key gap in microwave engineering education, by offering realistic opportunities to translate theory into real designs
Clear discussions of microwave IC categorization and roles; passive device impedances and equivalent circuits; coaxial and microstrip transmission lines; active devices (FET, BJT, DC Bias); and impedance matching
Microwave Circuit Design: A Practical Approach Using ADS
A new and highly efficient algorithm for nonlinear minimax optimization is presented. The algorithm, based on the work of Hald and Madsen, combines linear programming methods with quasi-Newton methods and has sure convergence properties. A critical review of the existing minimax algorithms is given, and the relation of the quasi-Newton iteration of the algorithm to the Powell method for nonlinear programming is discussed. To demonstrate the superiority of this algorithm over the existing ones, the classical three-section transmission-line transformer problem is used. A novel approach to worst-case design of microwave circuits using the present algorithm is proposed. The robustness of the algorithm is proved by using it for practical design of contiguous and noncontiguous-band multiplexers, involving up to 75 design variables.
The Electromagnetics Laboratories involve the disciplines of microwaves, millimeter waves, wireless electronics, and electromechanics. Students enrolled in microwave laboratory courses, such as Electrical Engineering 163DA and 164DB, special projects classes such as Electrical Engineering 199, and/or research projects, have the opportunity to obtain experimental and design experience in the following technology areas: (1) integrated microwave circuits and antennas, (2) integrated millimeter wave circuits and antennas, (3) numerical visualization of electromagnetic waves, (4) electromagnetic scattering and radar cross-section measurements, and (5) antenna near field and diagnostics measurements.
Many advances have been made in recent years in microwave packaging. They have become more reliable, smaller and lighter, as well as less expensive and with higher density circuit integration. There are a number of developments that have evolved that illustrate ways in which new packaging technologies are being used. These developments and technical advances, by companies such as Merrimac Industries, have further improved the packaging capabilities that should provide a whole new series of subsystems for the microwave industry.
Further, the device may also contain input and output RF matching networks or simply consist of the semiconductor die by itself. Millions of such discrete microwave transistors have been manufactured in packages of this type and used in a variety of amplifier and control system applications during the past 25 years. More recently, with the advent of monolithic microwave ICs (MMICs), a tiny chip may be mounted into a similar package that performs a single function, such as a switch, attenuator, mixer or amplifier. Or the chip may include more than one circuit function such as the mixer-preamplifier stage for a direct broadcast satellite front end, tens of millions of which have been made in the past five years.
At the next tier of the packaging integration hierarchy, Level 3, several Level 1 or 2 enclosures may be mounted on a board that is placed into a larger module housing. The degree of complexity at each level is dependent upon the circuit-partitioning methodology and the system architecture; assembly and testing considerations may be important factors as well. For more than 20 years, Level 3 packaging has been the dominant product design approach for microwave subsystem and system integration in military applications. That's partly because the large system contractors responsible for the functional partitioning of complex microwave hardware generally specify the piece parts that make up the system by adapting to internal manufacturing capabilities as well as outsourcing to qualified vendors that supply components.
Level 3 approaches that have appeared within the past 15 years include wafer-scale integration, by Westinghouse (now Northrop Grumman); microwave high-density interconnect, by General Electric (now Lockheed-Martin); flip-chip mounting, by Hughes Aircraft (now Raytheon Defense Systems); glass microwave ICs, by M/A-Com (now part of AMP Industries); compliant interconnect, by TRW; waffleline high-density packaging, by Harris; and microwave common modules, by a U.K. consortium.
The final level, Level 4, has evolved within the past five to seven years. This 3-D-subsystem level of integration has been spurred by the desire to realize even higher-density microwave packaging, driven by cost considerations and by the successful achievements of the digital circuit design community. For monolithic microwave ICs, higher-density integration results in fewer square millimeters of gallium arsenide substrate material and hence lower cost.
Recent advances in both hard- and soft-lamination technologies (low-temperature co-fired ceramic, or LTCC); high-temperature co-fired ceramic, or HTCC; and polymer materials) have demonstrated the potential capability of doing high-density routing and interconnections for microwave circuits. These technologies offer the reduction or elimination of wirebonds, increased reliability, improved yield and lowered fabrication costs. Multilayer substrates enable dense packaging of components and modules.
HTCC technology initially was used in VHF-UHF-RF transistor-chip packages that were subsequently expanded to include matching networks and cascaded stages. Attempts to extend the enclosures for packaging multiple MMIC chips have been fairly successful as long as refractory metal conductors could be gold- plated to minimize transmission line losses-buried traces in multilayer assemblies have been found to cause significant and unacceptable RF and dc attenuation. The ability to braze the ceramic to high-conductivity (both elec trical and thermal) metal baseplates that match GaAs' coefficient of thermal expansion have made the HTCC packages attractive for high-power, high-dissipation chip designs. But post-firing shrinkage factors have often caused uncontrollable misalignment in multilayer-circuit registration, inhibiting practical use at the higher microwave frequencies. And for experimental purposes the front-end tooling costs tend to be uneconomical.
Copper, silver and gold conductors can be used with LTCC technology because of its lower firing temperature, but tooling costs are comparable to those of HTCC. Maximum operating frequency is limited to about 10 GHz because of dielectric losses, but emerging developments promise to reduce those losses and improve performance. Multilayer substrates have been developed for a variety of complex microwave circuit designs and interconnection techniques, but attachment of active devices or chips must be surface-mounted or inserted in cavity cutouts with exposed conductors within the sublayers.
The stacked-tile concept consists of a 2 x 2 array of identical modules with multiple interconnection layers containing MMICs and other RF components mounted near the top surface for coupling to the antenna. Control-function and power-conditioning circuits are disposed on additional layers with the RF and dc manifolds near the bottom. This module architecture lends itself to semiautomated batch fabrication and assembly for low-cost subarray manufacture. The production methodology, together with the Merrimac Multi-Mix approach, points the way that microwave packaging technology appears to be heading.
The Multi-Mix process for microwave multilayer ICs and micro-multifunction modules was developed at Merrimac Industries based on fluoropolymer composite substrates. The fusion bonding of multilayer structures provides a homogeneous dielectric medium for superior electrical performance at microwave frequencies. The bonded layers may incorporate embedded semiconductor devices, etched resistors, passive circuit elements and plated-through via holes to form a 3-D subsystem Level 4 enclosure that requires no further packaging. In fact, the module structure is the package. The unit is rugged and lightweight, and its format-external interface and surface mount-is compatible with microstrip or coplanar waveguide planar transmission lines. 2ff7e9595c
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