Reference STATE OF THE ART Stan Augarten

ISBN 0-89919-195-9

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A Semiconductor Best-Seller
The µA709 Operational Amplifier


The µA702 gave rise to one of the greatest commercial and technical successes of the young semiconductor industry, the µA709 operational amplifier. Like its innovative predecessor, the 709 is employed chiefly as a difference amplifier - that is, as a chip which compares two incoming signals and releases a third that is an amplified measure of the difference between the two. But the 709, which was also designed by Robert Widlar, is far more powerful than the earlier chip, and it quickly became perhaps the most widely used operational amplifier in electronics.

  Millions of 709s have been sold, and both the 702 and 709 are still being made - a unique longevity record in an industry whose products usually become obsolete within only a few years. The 709 is faster and far more efficient than the 702 and has ten times the amplification: whereas the 702 can boost an incoming signal by some seven thousand times, the 709 can raise it an astounding seventy-thousand-fold. Until Widlar created the 709, such a chip was thought to be impossible.

  Thanks to its powerful properties, the 709 won an indispensable place in countless applications, from computers and stereos to airplanes and missiles. When it first appeared, the 709 cost more than $100, but the price has since fallen to a mere 45¢ - a typical price drop in an industry keenly affected by competition and the economies of mass production. The 709 ruled the field unchallenged until 1968, when Fairchild introduced the 741; unlike the 702 and 709, the new chip contained its own capacitors.

The µA709 has fourteen bipolar transistors and fifteen resistors. The transistors are the small boxlike elements with the connecting white lines; the resistors are the narrow U-shaped loops. The white lines are aluminum connectors. The thick dark brown wall-like features are isolation channels. Actual size: 0.60 inches square. Photo of


©Copyright Stan Augarten
This book is provided for general reference. The National Museum of American History and the Smithsonian Institution make no claims as to the accuracy or completeness of this work.

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