Gain

For other uses, see Gain (disambiguation).

In electronics, gain is a measure of the ability of a circuit (often an amplifier) to increase the power or amplitude of a signal. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical An electrical network is an interconnection of Electrical elements such as Resistors Inductors Capacitors Transmission lines Voltage Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. In Physics, power (symbol P) is the rate at which work is performed or energy is transmitted or the amount of energy required or expended for Amplitude is the magnitude of change in the oscillating variable with each Oscillation, within an oscillating system In the fields of communications, Signal processing, and in Electrical engineering more generally a signal is any time-varying or spatial-varying quantity It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. A ratio is an expression which compares quantities relative to each other In Telecommunication, signalling (UK spelling or signaling (US spelling has the following meanings The use of signals for controlling communications In Telecommunication, signalling (UK spelling or signaling (US spelling has the following meanings The use of signals for controlling communications It may also be defined as the decimal logarithm of the same ratio. In Mathematics, the logarithm of a number to a given base is the power or Exponent to which the base must be raised in order to produce

Thus, the term gain on its own is ambiguous. Ambiguity (Am-big-u-i-ty is the property of being ambiguous, where a Word, term notation sign Symbol, Phrase, sentence, or any For example, 'a gain of five' may imply that either the voltage, current or the power is increased by a factor of five. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical Electric power is defined as the rate at which Electrical energy is transferred by an Electric circuit. Furthermore, the term gain is also applied in systems such as sensors where the input and output have different units; in such cases the gain units must be specified, as in "5 microvolts per photon" for a photosensor. A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument

In laser physics, gain may refer to the increment of power along the beam propagation in a gain medium, and its dimension is m^-1 (inverse meter) or 1/meter. Laser science or laser physics is a branch of Optics that describes the theory and practice of Lasers Laser science is principally concerned with The active laser medium or gain medium is the source of optical Gain within a Laser.

1 Logarithmic units and decibels
2 See also

Logarithmic units and decibels

Power gain

Power gain, in decibels (dB), is defined as follows:

$Gain=10 \log \left( {\frac{P_{out}}{P_{in}}}\right)\ \mathrm{dB}$

where P_in and P_out are the input and output powers respectively. The power gain of an Electrical network is the ratio of an output power to an input power The decibel ( dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity relative to

A similar calculation can be done using a natural logarithm instead of a decimal logarithm. The natural logarithm, formerly known as the Hyperbolic logarithm is the Logarithm to the base e, where e is an irrational The result is then in nepers instead of decibels. For Neper as a mythological god see Neper (mythology, for the lunar crater named Neper see Neper (crater, and for the Scottish mathematician phycisist and

Voltage gain

When power gain is calculated using voltage instead of power, making the substitution (P=V ²/R), the formula is:

$Gain=10 \log{\frac{(\frac{{V_{out}}^2}{R_{out}})}{(\frac{{V_{in}}^2}{R_{in}})}}\ \mathrm{dB}$

In many cases, the input and output impedances are equal, so the above equation can be simplified to:

$Gain=10 \log \left( {\frac{V_{out}}{V_{in}}} \right)^2\ \mathrm{dB}$

and then:

$Gain=20 \log \left( {\frac{V_{out}}{V_{in}}} \right)\ \mathrm{dB}$

This simplified formula is used to calculate a voltage gain in decibels, and is equivalent to a power gain only if the impedances at input and output are equal. Joule's laws are a pair of laws concerning the heat produced by a current and the energy dependence of an Ideal gas to that of pressure volume and temperature respectively Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal Alternating current (AC

Current gain

In the same way, when power gain is calculated using current instead of power, making the substitution (P=I ²R), the formula is:

$Gain=10 \log { \left( \frac { {I_{out}}^2 R_{out}} { {I_{in}}^2 R_{in} } \right) } \ \mathrm{dB}$

In many cases, the input and output impedances are equal, so the above equation can be simplified to:

$Gain=10 \log \left( {\frac{I_{out}}{I_{in}}} \right)^2\ \mathrm{dB}$

and then:

$Gain=20 \log \left( {\frac{I_{out}}{I_{in}}} \right)\ \mathrm{dB}$

This simplified formula is used to calculate a current gain in decibels, and is equivalent to the power gain only if the impedances at input and output are equal. Joule's laws are a pair of laws concerning the heat produced by a current and the energy dependence of an Ideal gas to that of pressure volume and temperature respectively Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal Alternating current (AC

Example

Q. An amplifier has an input impedance of 50 ohms and drives a load of 50 ohms. When its input ( $V i n$ ) is 1 volt, its output ( $V o u t$ ) is 10 volts. What are its voltage gain and power gain?

A. Voltage gain is simply:

$\frac{V_{out}}{V_{in}}=\frac{10}{1}=10\ \mathrm{V/V}.$

The units V/V are optional, but make it clear that this figure is a voltage gain and not a power gain. Using the expression for power, P = V²/R, the power gain is:

$\frac{V_{out}^2/50}{V_{in}^2/50}=\frac{V_{out}^2}{V_{in}^2}=\frac{10^2}{1^2}=100\ \mathrm{W/W}.$

Again, the units W/W are optional. Power gain is more usually expressed in decibels, thus:

$G_{dB}=10 \log G_{W/W}=10 \log 100=10 \times 2=20\ \mathrm{dB}.$

A gain of factor 1 (equivalent to 0 dB) where both input and output are at the same voltage level and impedance is also known as unity gain. Mathematics For any number x: x ·1 = 1· x = x (1 is the multiplicative identity

This article contains material from the Federal Standard 1037C, which, as a work of the United States Government, is in the public domain. In Radio transmission, transmitter power output ( TPO) is the actual amount of power (in Watts of Radio frequency (RF energy The absolute gain of an antenna, for a given direction and Polarization, is the ratio of (a the power that would be required at the Input of In Negative feedback amplifiers loop gain refers to the product of the gain in the feedback loop and the feedback factor in that loop In Telecommunication, insertion gain is the Gain resulting from the insertion of a device in a Transmission line, expressed as the ratio of the signal The power gain of an Electrical network is the ratio of an output power to an input power In Telecommunications the term directive gain has the following meanings 1 In Telecommunications, net gain is the overall Gain of a transmission circuit. In a Spread spectrum system the process gain (or 'processing gain' is the ratio of the spread (or RF bandwidth to the unspread (or baseband bandwidth In a Spread spectrum system the process gain (or 'processing gain' is the ratio of the spread (or RF bandwidth to the unspread (or baseband bandwidth Automatic gain control (AGC is an adaptive System found in many electronic devices In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium In radio Telecommunications, effective radiated power or equivalent radiated power (ERP is a standardized theoretical measurement of radio frequency (RF The active laser medium or gain medium is the source of optical Gain within a Laser. Federal Standard 1037C, entitled Telecommunications Glossary of Telecommunication Terms is a United States Federal Standard issued by the General Services Administration A work of the United States government, as defined by United States copyright law, is "a work prepared by an officer or employee of the U The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone

Dictionary

-noun

The act of gaining.
What one gains, as a return on investment or dividend.
(electronics) The factor by which a signal is multiplied.

-verb

(transitive): To acquire possession of what one did not have before.

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