A Microwave Engineering Journey

   1952-1996        1996-1998        1998-2000        2003        2004        2005


Radar Era (1952-1961)
Missile Era (1961-1971)
Phased Array Era (1971-1980)
Early MMICs (1980-1990)
MMICs Today (1990-2004)

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The Fourth Ten Years of the Microwave Engineering Journey
The Early MMIC/Integrated Circuit Era (1980-1990)

In the early 1980's Glen Gaustad asked me to move from the Antenna Laboratory to join the Central Research Laboratories and participate in GaAs MMIC development. While there I shared an office with Bentley Scott. One of my first activities was to develop good quality switches. On the left are three shunt switch configurations that were considered. The next figure shows some of the switches and low-pass/high-pass filters used in phase shifter applications. The third figure shows a two inch wafer of these circuit forms. In 1985 I was awarded a patent for inventing the size-reduced shunt switch form. This was United States Patent Number 4,556,808 dated December 3, 1985.

One of the early phase shifters made use of series FET switches. The photo shows an example of this configuration. Although the shunt switches were larger they were found to offer better performance. The single-chip radar development made use of shunt switches.

The realization of the "Single Chip Radar module" first occured in 1985 when a nine member team of designers at Texas Instruments created an X-Band version using microstrip circuitry on a GaAs semiconductor substrate. This program won for them the award for the best technical innovation by a contractor from the Defense Advanced Research Projects Agency (DARPA). Members of the design team included W. R. Wisseman, L. C. Witkowski, G. E. Brehm, R. P. Coats, D. D. Heston, R. D. Hudgens, R. E. Lehmann, H. M. Macksey, and H. Q. Tserng. The Circuit Block Diagram and Chip Photo are shown at the left.
As the page title indicates, the transmission-line configuration of choice is an integrated circuit form. This marked the beginning of MMIC circuit development. Use of integrated circuits had finally reached the microwave industry. The nine figures below are a description of the process steps implemented in fabrication of early circuitry.

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