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 direct coupling, DC-coupled Electronic component, electronic voltage amplifier with a differential input, a (usually) Single-ended signaling, single-ended output, and an extremely high gain ( ...

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 responsible for creating and managing communications and information systems for the command and control of combined arms forces. It was established in 1860 by ...

Fort Monmouth, NJ Fort Monmouth is a former installation of the Department of the Army in Monmouth County, New Jersey and the site of a major upcoming Netflix film production campus, alongside a variety of other redevelopment. The site is surrounded by the commun ...

, 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. Karl Dale Swartzel Jr. (June 19, 1907 – April 23, 1998) was the inventor of the operational amplifier (or 'opamp'). He filed the patent for the 'summing amplifier' in 1941 when working at Bell Labs. References

1907 births 1998 dea ...

for use in the

Western Electric Western Electric Co., Inc. was an American electrical engineering and manufacturing company that operated from 1869 to 1996. A subsidiary of the AT&T Corporation for most of its lifespan, Western Electric was the primary manufacturer, supplier, ...

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. N ...

. Encouraged by George A. Philbrick, who was part of the Division 7 team, Julie designed a circuit using two dual-

triode A triode is an electronic amplifier, amplifying vacuum tube (or ''thermionic valve'' in British English) consisting of three electrodes inside an evacuated glass envelope: a heated Electrical filament, filament or cathode, a control grid, grid ...

vacuum tube A vacuum tube, electron tube, thermionic 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. It ...

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