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    what's the difference between passive and active components?

    i know passive componets include resistors and capacitors, and active componets include bipolar transistors and mos transistors. But what is the radical difference between them? :)

    thanks & B. R.

    •   Alt8th June 2004, 03:22

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    Re: what's the difference between passive and active compone

    I think that the main diferent is that passive components drain power to the source that are conected, insted of the active ones. Example

    A passive filted will drain current from the signal, but the active one, is not going to drain anything or olmost anything.

    Sorry about my english :P



    •   Alt8th June 2004, 03:47

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    Re: what's the difference between passive and active compone

    Main difference is that passive components can only waste(resistor) or accumulate(capacitor, inductor) energy. Active components can first off all amplify signal or generate it.



    •   Alt8th June 2004, 15:10

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    Re: what's the difference between passive and active compone

    thank you for all the help! :D

    I understand a little, maybe i need more time to get deep understanding. :)



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    Re: what's the difference between passive and active compone

    Another way to look at it is in form of energy

    Passive Components do not require a power supply to handle the signals that pass through them. They are used to store electrical charges, to limit or resist electrical current, and for filtering, surge suppression, measurement, timing, and tuning applications.

    Active Devices require a source of energy for its operation and have an output that is a function of present and past input signals



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    Re: what's the difference between passive and active compone

    I would say that (surprisingly i am not sure, but that's a very good thing)

    active devices are usually semiconductor devices that depend on (electron and holes) carriers for their operation, and hence require a source of energy(supply) that they can use to amplify signals (meaning generate their own power gain)

    passive devices are just materials that can dissipate or store energy. They can very well be made out of semiconductor devices, but in reality we get a lot of parasitics when we do that.

    The presence or absence of a source of energy determining the device operation would then be a fundamental difference.


    Active devices have memory since they can be modeled as a combination of passive devices that can be used as memory(e.g capacitors) so this is not a difference.

    ======================= SUMMARY
    If you look at active device models (e.g. mosfet), you will always find a dependent current or voltage source, which implies a source of power and a biasing point required for the derivation of such a model, whereas if you make a very detailed model of a spiral inductor, you will get only resistors, capacitors, and inductors but no dep. sources. so this seems to be the difference
    =======================



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    Re: what's the difference between passive and active components?

    Quote Originally Posted by leebluer View Post
    i know passive componets include resistors and capacitors, and active componets include bipolar transistors and mos transistors. But what is the radical difference between them? :)

    thanks & B. R.
    1.Active devices are capable of injecting power to the circuit but passive devices are incapable of supplying any energy
    2.Active devices contribute to amplification,power gain but passive devices are incapable to do so.
    3.Active devices require an additional source to be operational but passive devices donot require additional sources for the operation,instead they can store energy and release later.
    4.Active devices are capable of controlling the current like BJT(Current Controlled Devices),FET(Voltage Controlled Devices) etc while passive devices are not.
    5.Passive devices need the help of active devices to operate.It's necessary for any electronic circuit to have atleast an active device.
    6.Active Devices: Battery,BJTs,FETs,Diodes,PN Junctions
    Passive Devices: Resistors,Capacitors,Inductors etc.



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