Loebe Julie (December 10, 1920 - June 7, 2015) was an American engineer who has been credited with inventing the first

operational amplifier An operational amplifier (often op amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op amp produces an output potential (relative to c ...

circuit with differential inputs (1943), a topology which allowed much greater versatility in applications circuits and remains in wide use today.

Career

After earning a BSEE from the City College of New York in 1941, Julie worked at the

Army Signal Corps The United States Army Signal Corps (USASC) is a branch of the United States Army that creates and manages communications and information systems for the command and control of combined arms forces. It was established in 1860, the brainchild of Ma ...

Fort Monmouth, NJ Fort Monmouth is a former installation of the Department of the Army in Monmouth County, New Jersey. The post is surrounded by the communities of Eatontown, Tinton Falls and Oceanport, New Jersey, and is located about from the Atlantic Ocean. ...

, as a civilian engineer for two years. In 1943, NDRC Division 7 contracted Columbia University's Division of War Research to improve and simplify the multi-stage vacuum tube-based amplifier circuits designed by Karl D. Swartzel Jr. for use in the

Western Electric The Western Electric Company was an American electrical engineering and manufacturing company officially founded in 1869. A wholly owned subsidiary of American Telephone & Telegraph for most of its lifespan, it served as the primary equipment ma ...

gun director A director, also called an auxiliary predictor, is a mechanical or electronic computer that continuously calculates trigonometric firing solutions for use against a moving target, and transmits targeting data to direct the weapon firing crew. Na ...

. Encouraged by

George A. Philbrick George A. Philbrick was responsible, through his company George A. Philbrick Researches (GAP/R), for the 1953 commercialization and wide adoption of operational amplifiers, a now-ubiquitous component of analog electronic systems, and the invention ...

, who was part of the Division 7 team, Julie designed a circuit using two dual-

triode A triode is an electronic amplifying vacuum tube (or ''valve'' in British English) consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode). Developed from Lee De Forest's 19 ...

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

s that not only had the novel feature of a differential input, but used fewer tubes, was much faster (100 kHz gain-bandwidth product) and more power efficient (2 × 300 V at 10 mA, plus tube heater) than the previous circuits. After the war, Julie returned to university, earning an MS in mathematics from New York University in 1954. In 1956, he founded the company Julie Research Laboratories to produce precision resistors, calibration standards and related products. The company was acquired by Ohm-Labs in 2001.

References

{{DEFAULTSORT:Julie, Loebe American electrical engineers 20th-century American inventors 21st-century American inventors Analog electronics engineers American people of Polish descent 1920 births 2015 deaths

Career

See also

References