What is Gain: Definition and 416 Discussions

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. 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. It is often expressed using the logarithmic decibel (dB) units ("dB gain"). 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.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). In the field of audio and general purpose amplifiers, especially operational amplifiers, the term usually refers to voltage gain, but in radio frequency amplifiers it usually refers to power gain. 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. 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).
The gain of an electronic device or circuit generally varies with the frequency of the applied signal. Unless otherwise stated, the term refers to the gain for frequencies in the passband, the intended operating frequency range of the equipment.
The term gain has a different meaning in antenna design; antenna gain is the ratio of radiation intensity from a directional antenna to




P

in



/

4
π


{\displaystyle P_{\text{in}}/4\pi }
(mean radiation intensity from a lossless antenna).

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  1. T

    Gain of the system of amplifiers

    I need help with the two questions below please because i just don't understand it !1 Questions 1. A signal processing system consists of a preamplifier, an amplifier and a filter connected in series. At a given frequency the preamplifier and the amplifier have gains of 12 dB and 31 dB...
  2. W

    Gain an Awesome Perspective on the Scale of Things

    Wow, just found this great little link that gives an awesome perspective on the scale of things. Just thought I would share: http://www.pbs.org/wgbh/nova/elegant/scale.html
  3. Crumbles

    What is the relationship between a laser's gain curve and its natural linewidth?

    Can someone please explain what exactly the gain curve of a laser is? Is it exactly the same thing as the natural linewidth of the laser [a graph of intensity vs frequency] or am I off track? I found this graphhttp://www.phys.ksu.edu/perg/vqm/laserweb/Ch-5/C5s1p5.htm that tries to explain...
  4. P

    Insufficient Data: Calculating Orbital Energy Gain

    Came across another question during my exam review. Seems to me like there is insufficient data again. When the space shuttle delivers a crew to the international space station, it usually boosts the orbit of the station from about 320 km to 350 km. How much energy does the shuttle add to the...
  5. B

    How Does Antenna Gain Impact RF Energy Distribution?

    Hi, I'm having difficulty understanding how the gain of an antenna works. I appreciate that the gain effectively concentrates the available RF energy into a narrower beam but i can't fathom how this seems to mean that if i have a transmitter transmitting at say 100dBm that i can use antenna...
  6. S

    Engineers Needed How do you reduce THD in audio, how to get more gain, and more

    Greetings! I posted a few weeks ago about the preamp for the tape head I'm working on. I solved for all of my resistors and capacitor to get the right frequency response, and below is the theoretical frequency response, followed by what I actually get...
  7. R

    What purpose unity gain buffer amplifiers serve

    urgent help needed Can anyone tell me what purpose unity gain buffer amplifiers serve and why do you connect 2 low pass filters of same corner frequency by cascading them using one of these op amp buffers and not directly together. Also can you show me the diagram of this and where the...
  8. S

    Antenna Gain vs Effective Area

    I have been looking for info on the physical basis for this antenna equation : Gain = 4 * Pi * (Effective Area ) / Wavelength^2 I have found some tutorials that say it is based on reciprocity, and more specifically, on thermodynamic balance between a resistive load connected to an antenna...
  9. J

    GAIN and IMPEDANCE of a complex Circuit

    I am supposed to calculate the gain of the circuit given in the attachment. I have attached it in a word file. Z is the generic term for the effective resistance. I get that Z is Z = [jwL +(R/jwC)]/(R+1/jwC) Can someone tell me if this is correct? Also, now for the gain, it is...
  10. T

    Gain Insight into Sleep Disorders with this Interesting Article

    This was a very interesting article on sleep http://health.yahoo.com/health/centers/sleep_disorders/_101.html
  11. S

    What is 'Mirror Gain' for a Robot Parabolic Mirror?

    Hi, I've asked someone to make me a parabolic mirror for a robot and they want to know the 'mirror gain' i would like. Does anybody know what 'mirror gain' is? thanks
  12. M

    Could Superluminal Light Speeds Impact Theories on the Universe's Cold Death?

    What would the suggested effect from the results of this experiment on the predictions for the end of the universe, especially if it was a 'cold death'. The people doing the experiment mentioned that the state of cesium used existed at a near absolute zero temperature. In an older universe...
  13. N

    Can the water (100 oC) gain latent heat energy from the same temperature object?

    can the water (100 oC) gain latent heat energy from the same temperature object?
  14. S

    What RPM Gains Can Be Expected from a Lighter Axle on a Go Kart?

    I need to know whether to invest in a new lighter axel for a go kart Before I take the plunge, I'd like to get "some" kind of idea of the kinds of gains one can expect from this kind of change. The conditions as I know Them. the 5Hp engine achieves max torque at 5200-5400 RPM...
  15. Antonio Lao

    Certainty Gain by Uncertainty Power?

    One form of the Uncertainty Principle is given by \Delta p \Delta q \geq h where \Delta p is the change in momentum and \Delta q is the change in position and h is Planck's constant. If both side of the inequality is raise to the power n, does the new inequality expresses more certainty...
  16. T

    No Personal Gain: Is It Possible?

    is it possable for soemone to do something without any persnal gain? I think no...but then agian i think a lot of abstract things... DONT BOTHER READIGN THIS IT JUST RAMBLES AND I AM TIRED SO IT PRABLY WONT MAKE MUCH SENES: i dotn buy that good person who selflessly helps others its a...
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