Sep 22, 2013

IC Op Amps to the Left, Vacuum Tube Op Amps to the Right

History is obsessed with "the first" of whatever.  The first European to discover America. The first integrated circuit. The first operational amplifier (op amp).  New waves of historians then challenge "the first".  As school kids we were taught that in fourteen hundred and ninety-two Columbus sailed the ocean blue.  And now we know that Columbus probably didn't discover America.  The battle of who invented the IC was essentially settled as a draw between Robert Noyce and Jack Kilby; a topic for another day. As far as the first op amp, my college textbook [1] used the 741 (credit to Dave Fullagar) but claimed "the first" op amp was the uA709.  Bob Widlar designed the uA709 while at Fairchild Semiconductor and also receives credit for the uA702 as the first commercially successful op amp integrated circuit (IC).  I guess if the uA702 was commercially successful then the uA709 was wildly successful, an adjective that suited Bob Widlar. The uA701 is a footnote in history that we will discuss later. But they were integrated circuits.  Before integrated circuit op amps, there were vacuum tube op amps.

The landmark op amp ICs were developed in California, in what we call Silicon Valley, with notable exceptions.  The vacuum tube op amps were mostly developed on the East Coast.  In keeping with my fascination with historical footsteps, this bi-coastal aspect interests me.  But first, the question to be answered is who made the first vacuum tube op amp?

Credit generally goes to Lee De Forest for the first vacuum tube amplifier.  Historians now debate that.

De Forest was born in Council Bluffs, Iowa, and raised in Alabama.  He attended Yale University and worked generally on the East Coast.  However, in 1911 he moved west to become the research director of Federal Telegraph in Palo Alto, California [2].  There is that bi-coastal thing again - 60 years earlier.  Does anyone have a map that can show how far Federal Telegraph was from the site of the Wagon Wheel?


1. "Microelectronic Circuits", Sedra and Smith, 2nd Edition, 1987
2. "Fred Terman at Stanford", C. Stewart Gillmor, 2004

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