T here's little doubt that the first commercial operational amplifier was introduced to the market by George A. Philbrick Researches. That was in late 1952. But the forerunner of this amplifier and subsequent op amps as well as the basic design, many indicators suggest, came from a young engineer working at Columbia University: Loebe Julie.

The sole public credit for this profound development appeared in an acknowledgment for contributions "to some phases of this development" at the end of a technical article, "Analysis of Problems in Dynamics by Electronic Circuits," in the May 1947 issue of Proceedings of the I.R.E .

The lead author was John R. Ragazzini, a professor in charge of an electronics lab at Columbia University. If Julie really did the basic design-and there is much evidence of this (including correspondence from one of Ragazzini's co-authors)-why was Ragazzini the lead author and Julie essentially buried in a scant acknowledgment?

Ragazzini is no longer around to provide his reason. But some observers surmise that, 50 years ago, it was by no means uncommon for a professor to take credit for a major achievement of an underling.

In fact, there had been amplifiers to perform some of the math operations we associate with operational amplifiers as early as the period preceding World War II. But they were bulky and slow and not commercially available. A five-pentode design was used in Western Electric's M-IX artillery-gun director.

How did Julie get involved? It started with a bright physicist at the Massachusetts Institute of Technology, George Philbrick, who won a contract from the National Defense Research Council to build an electronic-sight simulator for fighter aircraft and a guided-bomb trainer simulator. The first system came to be known as Puss, for Pilot Universal Sight System. The second had twoelements: Guided Bomb (Azimuth Only), or Azon, and Guided Bomb (Range and Azimuth), or Razon.

Philbrick subcontracted the work. The Franklin Institute in Philadelphia was to design and construct the mechanical and optical system for a bombing simulator. The second contract called for what Philbrick termed an electronic analog computer/simulator using operational amplifiers like those in the M-IX gun director, which Bell Telephone Laboratories had developed for Western Electric.

The M-IX, Julie said, was very slow. It took more than half an hour to plot the differential equations for the trajectory of an artillery shell. The amplifiers had a corner frequency of about 1 Hz. That contract went to Columbia University.

One-man show
And here at Columbia was Loebe Julie, almost, but not quite, fresh out of school. He had earned his BSEE from the City College of New York in 1941, then spent a couple of years as a civilian engineer with the Army Signal Corps in Fort Monmouth, N.J. There he designed a compact dual-channel amplifier for a machine-gun and mortar locator.

Along came a job offer from Columbia University's Division of War Research to become the entire engineering staff at one lab, an offer that Julie accepted. Then came the subcontract from MIT and George Philbrick, who introduced Julie to the amplifiers in the M-IX gun director. There were too many stages, Julie felt, and the devices, at about five pounds each, were heavy. A power-supply console that may have weighed 1,000 pounds supported 50 amplifiers, he recalls.

Based on his e xperience building a compact amplifier at the Signal Corps, Julie explained to project administrator Ragazzini that he could simplify and improve the design. Ragazzini rejected Julie's concept, Julie recalls, maintaining that it could never work. Ragazzini denied Julie permission to try his design.

When Philbrick visited Columbia again, Julie explained his idea. Philbrick asked how long it would take to build such an amplifier. When Julie asked for 30 days, Philbrick asked Ragazzini to give him a try.

It was one of those wonderful success stories encountered so often in our industry. In 30 days, Julie completed an op amp with a corner frequency extended to 1 kHz, with padding resistors and capacitors to kill parasitic oscillation and to stabilize the summing, integrating and differentiating operations.

He also built four regulated power supplies that could drive as many as 50 amplifiers. These occupied the space of a portable typewriter, a sort of primitive ancestor of laptop computers-albeit lar ger.

Philbrick was more than pleased. He placed an order for 50 Julie amplifiers for the Puss, Azon and Razon projects.

When Julie's work on the amplifiers was almost completed, a short while before Philbrick placed his contract, Ragazzini hired two college professors, Robert Randall and Frederick Russell. To Ragazzini's displeasure, Julie taught them about his design. Ragazzini didn't particularly like Julie, Julie reported. He accused him of intellectual arrogance, deprived him of credit for his design and ended his draft deferment.

After a year's stint in the Army Signal Corps., Julie returned to school-New York University this time-for a master's degree in math in 1954. In 1956, he founded Julie Research Laboratories, which to this day makes calibration standards and precision components.

A decade earlier, in 1946, George Philbrick had started George A. Philbrick Researches, which sold analog c omputers for military aircraft. In 1951, the company sold an analog computer containing 40 K2-UXs (U for universal, X for experimental) to Stone and Webster. And in 1952, it offered the K2-W, the first commercial general-purpose differential op amp. The device had two miniature nine-pin 12AX7 high-mu dual triodes in a plastic shell that plugged into an octal socket. Julie's circuit was based on two octal-base 6SL7 medium-micron triodes, and it laid the groundwork for all subsequent op amps. The Philbrick amplifier had a gain of about 20,000 and a gain-bandwidth product of about 1 MHz. It dissipated about 4.5 W, and it cost $24.

Op-amp legacy
The op amp was a huge success. It generated sales; it generated new designs; and it generated competition. One op-amp competitor, Nexus Research Laboratory, was started by former Philbrick engineers Alan Pearlman and Roger Noble. The op-amp business looked good to a large conglomerate, Teledyne Inc., which acquired both Philbrick and Nexus in 1966, c reating Teledyne Philbrick Nexus, which, in time, became Teledyne Philbrick and then Teledyne Components. That company was acquired in 1993 and is now TelCom Semiconductor.

Acknowledgments: For help in providing information for this report, special thanks are due to Dan Sheingold, former engineer, director of applications engineering and vice president of marketing at George A. Philbrick Researches; to Robert A. Pease, former senior engineer, then vice president of development, at Philbrick; and to Loebe Julie, the former Columbia University engineer, now president of Julie Research Labs.

---

Suggestions for this series are welcome. call george rostky at (516) 562-5841 or via e-mail. .

Back to

Back to

Free Subscription to EE Times First Name Last Name Company Name Title Email address   Click here for your Free Subscription to EETimes Europe