A three-channel vector modulator with reference channel

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Date: Nov. 1998
From: Microwave Journal(Vol. 41, Issue 11)
Publisher: Horizon House Publications, Inc.
Document Type: Cover story
Length: 1,438 words

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A new and unique packaging technology has been introduced for commercial and military microwave components and subsystems. Multi-Mix[TM] packaging methodology is a unique process based on fluoropolymer composite substrates for application to microwave multilayer ICs and micro-multifunction modules (MMFM[TM]). MultiMix technology enables filter, multiplexers, MMICs and other active and passive circuits to be packaged individually or cascaded into supercomponents for mixer/preamplifiers, vector modulators, complex antenna feed-distribution networks, phased-array beamformers or components for monopulse receiving systems.

The technology is similar to an application-specific IC for RF/microwave applications. It employs a platform strategy modular architecture that integrates mathematical, electromagnetic, thermal and mechanical modeling capabilities on contemporary PCs, permitting total analysis of the microwave enclosure to be performed prior to actual hardware fabrication. The benefits of this process technology lie in the ability to integrate many circuit functions into a smaller volume. The resulting components feature weight and size reductions, improved performance and quality, less risk and cost savings.

THE MULTI-MIX PROCESS

The patent-pending Multi-Mix process begins with commercially available polstetrafluoroethylene (PTFE) composite, copper-clad laminate material having inherently low loss anti low dielectric constant microwave properties. The fusion bonding of multilayer structures provides a homogeneous dielectric medium for superior electrical performance at microwave frequencies. No sheet adhesive or prepreg is required although they may be used selectively according to the application. The bonded layers may incorporate embedded semiconductor devices, MMICs, etched resistors, passive circuit elements and plated-through via holes to form a three-dimensional subsystem enclosure that requires no further packaging. The MMFM structure is a total integrated packaging solution. The small footprint, low profile refit is rugged and lightweight, and the external surface-mount format is compatible with microstrip or coplanar waveguide planar transmission lines.

A low z-axis coefficient of thermal expansion (CTE) (close to that of copper) ensures reliability of plated-through holes. Controlled x-/y-plane thermal expansion, together with a low expansion modulus, affords good reliability of surface-mounted devices in the most severe thermal cycling and thermal shock environments. Furthermore, a low and uniform thermal coefficient of dielectric constant coupled with the material's low CTE produces consistent electrical performance over a wide operating temperature range.

Complex microwave circuit patterns anti transmission-line geometries may...

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Gale Document Number: GALE|A53392501