Gain

From Wikipedia, the free encyclopedia

In electronics, gain is usually taken as the mean ratio of the signal output of a system to the signal input of the system. A gain of five would imply that either the voltage or power is increased by a factor of five.

In electronics, it is common to use logarithmic units to measure gain. Originally, the bel was used:

Gain=log_{10}(\frac{P_2}{P_1}) (bels)

where P1 and P2 are the input and output powers respectively.

Using the bel unit, however, results in small numbers, so the decibel (one tenth of a bel) became popular in its place. As there are ten decibels (dB) in a bel:


Gain=10 \times log ({\frac{P_2}{P_1}})dB

(A similar unit using natural logarithms is called the neper.)

When gain is calculated using voltage instead of power, making the substitution (P=V2/R), the formula is:


Gain=10{\times}log{\frac{(\frac{{V_2}^2}{R})}{(\frac{{V_1}^2}{R})}}dB

Gain=10{\times}log{(\frac{V_2}{V_1}})^2 dB

Gain=20{\times}log ({\frac{V_2}{V_1}})dB

This formula only holds true if the load impedances are identical. In many modern electronic devices, output impedances are low enough and input impedances high enough that load can be ignored without significantly affecting the calculation.

If an amplifier produces an output of 1 volt into a 1 ohm load, then it is providing 1 watt of output power. If the amplifier is then altered to produce an output of 10 volts into the same load, it is now providing 100 watts of output power (P= {{V^2}\over R}) \!\. Therefore:

voltage gain = 10 times (10 dB)

power gain = 100 times (20 dB)

A gain of factor 1 or (equivalent to 0 dB) where both input and output are at the same voltage level is also known as unity gain.

This article contains material from the Federal Standard 1037C, which, as a work of the United States Government, is in the public domain.

Retrieved from "http://en.wikipedia.org../../../g/a/i/Gain.html"
Advanced Search
Included Web Search Engines


Safe Search

close

Top Matching Results

Occasionally Search.com will highlight specialized results that are based on the context of your query. Examples of specialized results include specific links to news, images, or video.

Top Matching Results may highlight information from other Search.com pages, content from the CNET Network of sites, or third party content. The listings are based purely on relevance. Search.com does not receive payment for listings in this section but our partners that provide this data may get paid for listing these products.

Sponsored Links

This section contains paid listings which have been purchased by companies that want to have their sites appear for specific search terms and related content. These listings are administered, sorted and maintained by a third party and are not endorsed by Search.com.

Search Results

Search.com sends your search query to several search engines at one time and integrates the results into one list which has been sorted by relevance using Search.com's proprietary algorithm. You can customize the list of search engines included in your metasearch from the preferences.

The search engines that are used in your metasearch may allow companies to pay to have their Web sites included within the results. To view the Paid Inclusion policy for a specific search engine, please visit their Web site. Search.com does not accept payment or share revenue with any search engine partner for listings in this section.