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    What is the use of bypass capacitors in (BJT)amplifier circuits?

    Often, bypass capacitors which are labelled as Ce are used in amplifier circuits. What is their necessity and what is their function?

    •   Alt7th January 2012, 17:46

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    Re: What is the use of bypass capacitors in (BJT)amplifier circuits?

    Ce is in parallel with Re.
    Re fix the bias voltage at emitter.
    this is DC. under ac signal conditions , Re is effectively shorted by the Ce , as its impedance will be zero at ac.


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    •   Alt7th January 2012, 18:09

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    Re: What is the use of bypass capacitors in (BJT)amplifier circuits?

    Ce is used when an emitter resistor Re is used to set the bias or the operating point. Re stabilizes the bias level by introducing negative feedback but also reduces signal amplification or gain. By bypassing Re with a capacitor, DC stability is unchanged but AC signal feedback and gain reduction is avoided.
    Last edited by Pjdd; 7th January 2012 at 20:03.



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