Electrothermal feedback
Encyclopedia
Electrothermal feedback is a concept in electronics
that describes the interaction of the electric current
and the temperature
in a device with a temperature-dependent electrical resistance
. This interaction arises from Joule heating
.
The temperature-dependence of the electrical resistance is described by the derivative
of the resistance with respect to temperature
. Semiconductors typically exhibit a negative 
. Superconductors exhibit a large positive 
on the superconducting phase transition. Normal (non-superconducting) metals typically exhibit a positive 
that decreases to zero at very low temperatures.
If a device has a positive
, an increase in temperature (for example, due to a thermal fluctuation or the absorption of a photon
) will increase the electrical resistance
. If the device is biased with a constant voltage 
, this increase in resistance will decrease the Joule power 
. The decrease in Joule heating will cause the device to return to its equilibrium temperature. This is known as negative electrothermal feedback, as the change in Joule heating opposes the change in temperature. If the device is instead biased with a constant current 
, the Joule power 
will increase if the temperature increases. Thus the Joule heating amplifies a change in temperature, an effect known as positive electrothermal feedback. The situation is reversed for the case of a negative 
.
Electrothermal feedback is important for describing the performance of several types of photodetectors such as the bolometer
, the transition edge sensor
, and the superconducting nanowire single-photon detector
.
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
that describes the interaction of the electric current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
and the temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
in a device with a temperature-dependent electrical resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
. This interaction arises from Joule heating
Joule heating
Joule heating, also known as ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor releases heat. It was first studied by James Prescott Joule in 1841. Joule immersed a length of wire in a fixed mass of water and measured the temperature...
.
The temperature-dependence of the electrical resistance is described by the derivative
Derivative
In calculus, a branch of mathematics, the derivative is a measure of how a function changes as its input changes. Loosely speaking, a derivative can be thought of as how much one quantity is changing in response to changes in some other quantity; for example, the derivative of the position of a...
of the resistance with respect to temperature
. Semiconductors typically exhibit a negative . Superconductors exhibit a large positive on the superconducting phase transition. Normal (non-superconducting) metals typically exhibit a positive that decreases to zero at very low temperatures.If a device has a positive
, an increase in temperature (for example, due to a thermal fluctuation or the absorption of a photonPhoton
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
) will increase the electrical resistance
. If the device is biased with a constant voltage , this increase in resistance will decrease the Joule power . The decrease in Joule heating will cause the device to return to its equilibrium temperature. This is known as negative electrothermal feedback, as the change in Joule heating opposes the change in temperature. If the device is instead biased with a constant current , the Joule power will increase if the temperature increases. Thus the Joule heating amplifies a change in temperature, an effect known as positive electrothermal feedback. The situation is reversed for the case of a negative .Electrothermal feedback is important for describing the performance of several types of photodetectors such as the bolometer
Bolometer
A bolometer is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley...
, the transition edge sensor
Transition edge sensor
A transition edge sensor or TES is a type of cryogenic particle detector that exploits the strongly temperature-dependent resistance of the superconducting phase transition.-Principle of operation:...
, and the superconducting nanowire single-photon detector
Superconducting nanowire single-photon detector
The superconducting nanowire single-photon detector is a type of near-infrared and optical single-photon detector based on a current-biased superconducting nanowire. It was first developed by scientists at Moscow State Pedagogical University in 2001....
.