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Why the voltage gain of an FET amplifier is generally less than that obtained using BJT amplifier?
A FET (Field Effect Transistor) is mainly used when the input signal needs to be isolated from the output. A FET has a very high input resistance, so very little current is required from the input. Voltage gain is not the main objective when using a FET.
Does the power amplifier amplifies the power?
the final stage of a power amp is a current amplifier in a bipolar design and a voltage amp in a FET design.
A junction FET can be used as a voltage variable resistor at which stage?
nnm,n,n,mn
What is input impedance of fet amplifier?
Zin=Vds/Id [Vds=drain to source voltage ; Id = drain current]
Fet in cut off voltage?
fet is a voltage controlled device...cut off voltage in fet refers to that voltage of the gate - source junction at which the current flow through channel is zero
What is Cut-off voltage in fet?
fet is a voltage controlled device...cut off voltage in fet refers to that voltage of the gate - source junction at which the current flow through channel is zero
How can transistors act as amplifiers?
The small signal model for the common source FET can be used for analysing the basic FET amplifierconfigurations:(i)common source(CS),(ii)commondrain(CD) or source follower,and(iii)common gate(CG). The CS amplifier which provides good voltage amplification is most frequentlyused.The CD amplifier with high input impedance andnear-unity voltage gain is used as a buffer amplifier and the CG amplifier is used as a high frequencyamplifier.The small signal current-sourcemodel for the FET in CS configuration and the voltage source model can be derived by finding the Thevenin'sequivalent for the output part of amplificationfactor,drain resistance andtransconductance/mutual conductance of the FET.
What is the voltage gain of the FET amplifier?
It can be answered in two ways : 1. ratio of output & input voltages [Vout / Vin] i.e Drain voltage(Vds)/Source voltage(Vs). 2. multiplication of trans-conductance & drain resistance .
What is the simplest way to convert capacitance to voltage?
If it is a variable cap, apply AC signal to the capacitor as per its specifications.This is done because the variation in the voltage gives a corresponding current output due to the charging and discharging of capacitor. Then a Trans-impedance amplifier can be used to convert this input current to voltage. Current amplifier can be used to amplify the current at the input of the trans-impedance amplifier. Similarly a voltage amplifier can be used at the out put of the trans-impedance amplifier to amplify the voltage output.
Were do you buy a voltage amplifier?
In audio look at an amplifier. It will be always a voltage amplifier.
What are voltage controlled devices?
FET
How does power amplifier differ from a conventional voltage amplifier?
A voltage amplifier does not have to supply significant current bur a power amplifier does.
