Interconnection and Assembly System for MMIC Circuits

June 1, 2008

Sophia Wireless of Chantilly, VA is using a micromachining approach to build integrated circuits, delivering a product that could offer size, weight, and cost benefits to the radar and aviation markets.

Funded by the Missile Defense Agency (MDA), the company is working to improve interconnect performance in hardware such as microwave systems, wireless telecommunications, and radars. Sophia Wireless has built filters at various frequencies, and integrated transceivers for E-band pointto- point applications using some of these technologies.

MDA predecessor BMDO originally funded Sophia's work in 2000 to develop a novel interconnection and assembly system for monolithic microwave integrated circuits (MMICs), with the technology having the potential to reduce assembly cost while improving interconnect performance. The company, previously known as Virginia Millimeter Wave, received Phase I and Phase II Small Business Innovation Research (SBIR) awards for the project.

The company has employed micromachining techniques to build integrated circuits, and their approach focuses on MMICs, combining them with other active components such as diodes and transistors, as well as passive components such as resistors and capacitors, to create integrated solutions for millimeter- wave applications.

MMICs serve as great amplifiers and frequency-conversion devices, or frequency multipliers, but they lack some parts that would allow them to operate as transceivers — or devices for both sending and receiving signals. Those missing parts, generally referred to as resonant passive devices, include such components as filters, diplexers, resonators, and couplers — larger-scale devices that are typically difficult to include on a MMIC and that require very low-loss propagation of signals. Since MMICs conventionally are optimized for small size and low cost, putting such resonant passive devices on the gallium arsenide (GaAs) area of a MMIC would be an inefficient use of space. So a transceiver that involves a MMIC typically comprises a MMIC plus resonant passive devices that are not integrated into the MMIC.

How it Works

Sophia's focus is on integrating those devices. The company's patented process uses silicon and micromachining techniques for microelectromechanical systems (MEMS) to make the lowloss resonant passive structures. The silicon-MEMS approach also is good at providing a substrate and a sort of second-level packaging for the MMIC, integrating the usual MMIC pieces with the resonant passive components to form integrated transceivers. Sophia uses the term "waferlevel integrated transceivers" to describe its technology.

The benefits should appeal to makers of electronic equipment such as radars, sensors, and communications devices in which size and weight are issues, such as in aircraft or satellites. Sophia expects the technology to be a good fit for equipment that runs on frequencies of 8 gigahertz or higher.

Sophia is currently marketing and selling its line of solid-state power amplifiers (SSPAs) for satellite communications and broadcasting applications. Both of these mobile applications represent areas in which size and weight can be critical. Sophia's solidstate amplifier line uses some of the same integration and miniaturization techniques.

Sophia's technique eliminates the need for circuit boards and housing, making for circuits that are about one-fifth (or even one-tenth) the weight of competing circuit assemblies. Sophia researchers also claim their product is about one-third the size of competing circuits comprising MMICs with resonant passive components. Another key benefit of the approach is fewer manufacturing steps. A MEMS approach (involving nonmoving parts and using micromachining surface-mount techniques) eliminates hand-tuning and hand-assembly.

Where it Stands

The company's commercialization approach has been to sample the technology, in a "proof of concept" fashion, for systems under development and likely to be fielded within a year. The company has pursued qualification of its technology for systems used in flight, and Sophia has supplied product to the Boeing Company for some advanced systems that Boeing is developing.

The unmanned aerial vehicle (UAV) market is particularly attractive to Sophia because of the growing number of missions involving UAVs and the performance demanded from systems used in these missions, which can include transceiver-equipped radar and surveillance applications.

The automotive radar market is also a potential application area. An allocated band of 77 gigahertz for automotive radar applications is an appropriate fit for Sophia's technology, and represents an environment in which size and weight are essential components, as are cost, vibration performance, and temperature performance.

More Information

For more information on Sophia Wireless's MMIC assembly system, click here  . (Source: MDA TechUpdate, Missile Defense Agency, National Technology Transfer Center Washington Operations.)

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