By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. {\displaystyle I_{\text{b}}} {\displaystyle P=I^{2}R} By definition, “Gain” is the output value versus input value. 2 A similar calculation can be done using a natural logarithm instead of a decimal logarithm, resulting in nepers instead of decibels: The power gain can be calculated using voltage instead of power using Joule's first law An unrealized gain occurs when the current price of a security is higher than the price the investor initially paid for the security, net of brokerage fees. / b to [1] It is often expressed using the logarithmic decibel (dB) units ("dB gain"). {\displaystyle V_{\text{in}}} , the formula is: In many cases, the input and output impedances are equal, so the above equation can be simplified to: 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. This exemption also applies to reserves from these properties brought into income in a tax year. The current gain for the common-base configuration is defined as the change in collector current divided by the change in emitter current when the base-to-collector voltage is constant. Such is the case with the operational transconductance amplifier, which has an open-loop gain (transconductance) in siemens (mhos), because the gain is a ratio of the output current to the input voltage. {\displaystyle I_{\text{c}}} In the bipolar transistor example, it is the ratio of the output current to the input current, both measured in amperes. R 4 {\displaystyle I_{\text{c}}} https://www.britannica.com/technology/current-gain, semiconductor device: Bipolar transistors. 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 the responsivity of a photosensor. is the power applied to the input, in {\displaystyle h_{\text{fe}}} b [4] A gain greater than one (greater than zero dB), that is amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one.[4]. The current [i.sub.1] is copied to the output section with a, Figure 4(a) showed the gain simulation results, where the set of solid curves represent the, 367 and 6038B provide a regime of substantive and procedural requirements that must be met to apply the subchapter C rules to avoid, At the heart of this new device, ST's advanced double-metal planar base island technology enables the 3STL2540 to maintain consistently high, In turn, the increase in recombination rate degrades the, On the basis of the MBE technology, the high, Dictionary, Encyclopedia and Thesaurus - The Free Dictionary, the webmaster's page for free fun content, Coupling vibration analysis of full-vehicle vehicle-guideway for maglev train, A Programmable Biopotential Aquisition Front-end with a Resistance-free Current-balancing Instrumentation Amplifier, High Frequency InGaAs MOSFET with Nitride Sidewall Design for Low Power Application, Simple low cost cupric oxide nanoparticle synthesis using co-precipitation method as a photodetector application, Single-phase energy metering chip with built-in calibration function, Final regulations address gain recognition agreements and other cross-border transfer reporting, 100 nm AlSb/InAs HEMT for ultra-low-power consumption, low-noise applications, Latest Bipolar Power Transistor from STMicroelectronics Rivals MOSFET Energy Efficiency in Space-Saving Outline, Damage induced by neutron radiation on output characteristics of solar cells, photodiodes, and phototransistors, A wideband CMOS current-mode down-conversion mixer for multi-standard receivers, Generalized analytical model for SiC polytypic heterojunctions/Uldistatud analuutiline mudel SiC-polutuupsetele heterosiiretele, Current Ideas in Mechanics and Related Fields. For Example: We have an amplifier with a current gain of 500 (Δi = … = and output impedance in Using the expression for power, P = V2/R, the power gain is: Again, the units W/W are optional. P The most useful amplifier…. {\displaystyle P_{\text{in}}/4\pi } More in-depth transistor gain equations and theory. {\displaystyle P_{\text{out}}} {\displaystyle h_{\text{fe}}} h It is usually defined as the mean ratio of the signal amplitude or power at the output port to the amplitude or power at the input port. or / The term gain alone is ambiguous, and can refer to the ratio of output to input voltage (voltage gain), current (current gain) or electric power (power gain). P V Announcing our NEW encyclopedia for Kids! π The gain of an electronic device or circuit generally varies with the frequency of the applied signal. I (or slope of the {\displaystyle P=V^{2}/R} The "current gain" of a bipolar transistor, When its input ( . The "gain" of a bipolar transistor normally refers to forward current transfer ratio, either hFE ("beta", the static ratio of Ic divided by Ib at some operating point), or sometimes hfe (the small-signal current gain, the slope of the graph of Ic against Ib at a point). When undertaking many calculations the transistor current gain is given in terms of the Greek letter Beta; β. R V R 2 I In the cases above, gain will be a dimensionless quantity, as it is the ratio of like units (decibels are not used as units, but rather as a method of indicating a logarithmic relationship). h R Although it is not strictly exact, the equation below is more than accurate enough for all practical calculations. Current Gain (Δi) The current gain is obtained by dividing the output by the input current of the amplifier. Search current gain and thousands of other words in English definition and synonym dictionary from Reverso. ). An amplifier has an input impedance of 50 ohms and drives a load of 50 ohms. Q. ; the formula is: In many cases, the input impedance FE = Power gain, in decibels (dB), is defined as follows: where This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. I {\displaystyle h_{\text{FE}}} In the same way, when power gain is calculated using current instead of power, making the substitution . h P {\displaystyle R_{\text{out}}} Unless otherwise stated, the term refers to the gain for frequencies in the passband, the intended operating frequency range of the equipment. out https://en.wikipedia.org/w/index.php?title=Gain_(electronics)&oldid=947425706#Current_gain, Wikipedia articles incorporating text from the Federal Standard 1037C, Creative Commons Attribution-ShareAlike License, This page was last edited on 26 March 2020, at 06:33. The current gain for the common-base configuration is defined as the change in collector current divided by the change in emitter current when the base-to-collector voltage is constant. in {\displaystyle V_{\text{out}}} out In the case of other devices, the gain will have a value in SI units. (mean radiation intensity from a lossless antenna). Typical common-base current gain in a well-designed bipolar transistor is very close to unity. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. An eligible individual is entitled to a cumulative lifetime capital gains exemption (LCGE) on net gains realized on the disposition of qualified property. V The fraction of the current flowing into the emitter of a transistor which flows through the base region and out the collector. In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port[1][2][3][4] by adding energy converted from some power supply to the signal. Power gain is more usually expressed in decibels, thus: 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. Δi = Iout / Iin. It is usually defined as the mean ratio of the signal amplitude or power at the output port to the amplitude or power at the input port. ) is 10 volts. . I out This transistor gain equation is the one that is seen in most instances. A gain greater than one (greater than zero dB), that is amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one. It is often expressed using the logarithmic decibel (dB) units ("dB gain"). is the power from the output. {\displaystyle I_{\text{b}}} [4] In the field of audio and general purpose amplifiers, especially operational amplifiers, the term usually refers to voltage gain,[2] but in radio frequency amplifiers it usually refers to power gain. All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. in In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port by adding energy converted from some power supply to the signal. Typical common-base current gain in a well-designed bipolar transistor is very close to unity. are equal, so the above equation can be simplified to: This simplified formula, the 20 log rule, 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. P P c The most useful amplifier… https://encyclopedia2.thefreedictionary.com/current+gain. graph, for The units V/V are optional but make it clear that this figure is a voltage gain and not a power gain. . {\displaystyle P_{\text{in}}} Figure 4(a) showed the gain simulation results, where the set of solid curves represent the current gain [H.sub.21] values and the set of open curves represent the unilateral power gain U values, from which the cut-off frequency [f.sub.t] and the maximum oscillation frequency [f.sub.max] can be extracted.
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