John Bertrand Johnson
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John Bertrand Johnson (October 2, 1887 – November 27, 1970) (''né'' Johan Erik Bertrand) was a Swedish-born American electrical engineer and physicist.Johnson biography, p. 2
/ref> He first explained in detail a fundamental source of random interference with information traveling on wires.


Early life

According to Steve Johnson: "John Bertrand Johnson was a cousin of my father, Dr. John A. Johnson. Bert was born to my grandfather's sister, who never married, in Sweden. Bert had no schooling in Sweden and lived in extreme poverty. My grandfather sent for him as a teenager and he ended up on their farm in far Northwestern
North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, ...
, U.S. My grandfather sent Bert to school and he finally graduated from high school and went on get his PhD in Physics from Yale. I was told that he worked with Einstein and went on to be director of Bell Labs ... I met Bert several times, but I was fairly young and most of the family history is lost..I am in the process of trying to piece together more details". According to the IEEE biography entry in, Johnson was born in the Carl Johan parish of Goteborg, Sweden and christened on October 7, 1887. His birth certificate only recorded his mother's name (Augusta Mathilda Johansdotter 9b. 1866) and his surname is thus derived from his assumed father Carl Bertrand Johnson. He emigrated to the US in 1904 and attended Yale. Johnson became a US citizen in 1928. In 1919 he married Clara Louisa Conger (d.1961) and in 1961 he married Ruth Marie Severtson Bowden. He had two sons by his first marriage, Bertrand Conger and Alan William. John Bertrand Johnson died aged 83 in
Orange, New Jersey The City of Orange is a township in Essex County, in the U.S. state of New Jersey. As of the 2010 U.S. census, the township's population was 30,134, reflecting a decline of 2,734 (−8.3%) from the 32,868 counted in 2000. Orange was original ...
, US, on November 27, 1970.


Career

In 1928, while at
Bell Telephone Laboratories Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...
he published the
journal A journal, from the Old French ''journal'' (meaning "daily"), may refer to: *Bullet journal, a method of personal organization *Diary, a record of what happened over the course of a day or other period *Daybook, also known as a general journal, a ...
paper "''Thermal Agitation of Electricity in Conductors''". In electronic systems, ''
thermal noise A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...
'' (now also called ''Johnson noise'') is the
noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...
generated by thermal agitation of electrons in a conductor. Johnson's papers showed a statistical fluctuation of
electric charge Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons res ...
occur in all
electrical conductor In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gene ...
s, producing random variation of
potential Potential generally refers to a currently unrealized ability. The term is used in a wide variety of fields, from physics to the social sciences to indicate things that are in a state where they are able to change in ways ranging from the simple r ...
between the conductor ends (such as in
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 potential difference has been applied. The type known as ...
amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost t ...
s and
thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of th ...
s). Thermal noise power, per
hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that o ...
, is equal throughout the
frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...
. Johnson deduced that thermal noise is intrinsic to all resistors and is not a sign of poor design or manufacture, although resistors may also have excess noise.


Field-effect transistor

Johnson was possibly among the first people to make a working
field effect transistor The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs contro ...
, based on
Julius Edgar Lilienfeld Julius Edgar Lilienfeld (April 18, 1882 – August 28, 1963) was an Austro-Hungarian, and later American (where he moved in 1921) physicist and electrical engineer, who was credited with the first patent on the field-effect (FET) (1925). Be ...
's US Patent 1,900,018 of 1928. In sworn testimony to the U.S. patent office in 1949, Johnson reported "...although the modulation index of 11 per cent is not great,...the useful output power is substantial...it is in principle operative as an amplifier". On the other hand, in an article in 1964 he denied the operability of Lilienfeld's patent, saying "I tried conscientiously to reproduce Lilienfeld’s structure according to his specification and could observe no amplification or even modulation."J. B. Johnson, "More on the solid-state amplifier and Dr. Lilienfeld," ''Physics Today'', May 1964


See also

*
Johnson–Nyquist noise Johnson–Nyquist noise (thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens reg ...
*
Timeline of thermodynamics, statistical mechanics, and random processes A timeline of events in the history of thermodynamics. Before 1800 * 1650 – Otto von Guericke builds the first vacuum pump * 1660 – Robert Boyle experimentally discovers Boyle's Law, relating the pressure and volume of a gas (pu ...


References


External articles and references

* J. B. Johnson, "
Thermal Agitation of Electricity in Conductors
'". The American Physical Society, 1928. *
Federal Standard 1037C Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, a ...
and MIL-STD-188 {{DEFAULTSORT:Johnson, John B. 1887 births 1970 deaths Scientists at Bell Labs Swedish emigrants to the United States American electrical engineers