EARLY TRANSISTOR
AND DIODE HISTORY
AT BELL LABS
Art Uhlir Jr.
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Oral History – (Continued) |
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The top left photo shows a silicon point
contact microwave diode, manufactured by Microwave Assoc in 1965 when Art
Uhlir was the VP of the Semiconductor Operation. The top right photo illustrates the types of Western Electric
diodes that Art used in his work at Bell Labs in the mid 1950s which lead to
the discovery of the varactor diode and the parametric amplifier. The white unit is a silicon point contact
diode from 1949, the brown unit is a germanium point contact diode from 1950
and the grey unit is a diffused silicon diode from 1959. Art describes his involvement with all
these types of diodes in this Oral History.
To the right is a photo from an excerpt of “A History of Engineering
and Science in the Bell System – Electronics Technology (1925-1975)”,
published by AT&T. Art is shown standing next to some of the equipment he
used to demonstrate power gain from a newly developed diode. According to the text, “In studying
frequency conversion effects, A Uhlir Jr. realized that the variable
reactance of the diode normally led to power gain in the upward frequency
shift … Using a gold alloy diode, experimentally he obtained an up-conversion
gain of 5.7 dB between 75 MHz and 6175 MHz output”. Since Art’s pioneering diode work at BTL in the 1950s, billions
of varactor diodes/parametric amplifiers have been manufactured and
sold.
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Art Uhlir Jr. is shown
standing next to the modulator test setup.
Seated is P.I. Sandmark, the project system engineer.
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COPYRIGHT
© 2004 by Jack Ward. All Rights
Reserved. http://www.transistormuseum.com/ PAGE
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