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Hi.
Large signal means nothing.
Small signal means nothing.
Just as a large boat and a small boat tell nothing about their size.
Signal magnitude is measured in Volts, Watts, dBm, Amperes, lumens,...
Miguel
Small signal analysis focus on a "small" linear region, that's why it call small signal. Since it focus on the linear region, many math like linear algebra can be used.
Large signal does not focus on a small region.
large signal is a signal whose magnittude drives the transistor operating in the linear active region to the non-linear region(i.e the saturation region or the cut-off region).
generally small signal amplifiers/ devices are the first stages of any system be it a communication system/a sensory system.the are highly sensitive to small changes.
on the other hand large signal devices are used at the last stages. these devices give considerable power boost to the signal. generally two devices are used in push pull configuration.
Hi,
Small signal is the S parameter for the linear working of amplifiers for example and large signal is for the nolinear working to have power and intermodulation of amplifiers
Response of an amplifier can be shown by :
vo=a0 + a1*vin^1 + a2*vin^2 .........
here a0 is defined as ur bias point..
in small signal analysis we can neglect higher order parts of o/p..
ur o/p will become : vo=a0 + a1*vin^1
and for operating w/o disturbing the bias (a1*vin^1<<a0)
It sounds a little funny, but there is something associated with it. Did you know that a large signal produces high current while a small signal produces low current. In order to produce a large signal don't you need gain. So you increase the gain by lowering the emitter resistor and this makes the transistor current higher. So a large signal is associated with a high current transistor.
While we talk about Large and small signals, I can find Large signal analysis assosciated with high frequency analysis and small signal for low frequency analysis where capacitors are prime at high frequencies.Is there any correlation?
Small Signal refer to amplying region, where ur output signal is linear to ur given input.
Large Signal normally refer to signal saturating with a max current application where the output is not linear to the given input.
First of all, signal strengths are all relative.
Small signal analysis is the measurement/calculation of the tangent of the transfer function. But large signal is actually moving along the transfer function.
When a circuit is perfectly linear, all signal is small since the tangent is constant. However, almost all active components will have some kind of non-linearity, which makes transfer function non-linear. Therefore, large signal analysis is to examine the behavior of these non-linearity, or worse, functionality.
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