In deriving ac equivalent circuit for an amplifier circuit, we short circuit___________?

Related Mcqs:

1. An amplifier without feedback has a voltage gain of 50,input resistance os 1 KΩ & Output resistance of 2.5KΩ.The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 is___________?

   A. 1/11KΩ
   B. 1/5KΩ
   C. 5KΩ
   D. 11KΩ

2. An amplifier using an opamp with slew rate SR=1v/µsec has a gain of 40db.if this amplifier has to faithfully amplify sinusoidal signals from dc to 20 KHz without introducing any slew-rate induced distortion, then the input signal level must not exceed________?

   A. 795mV
   B. 395mV
   C. 795 mV
   D. 39.5mV

3. Three identical amplifiers with each one having a voltage gain of 50,input resistance of 1KΩ & output resistance of 250 ,are cascaded.The open circuit voltage gain of combined amplifier is_________?

   A. 49dB
   B. 51dB
   C. 98dB
   D. 102dB

4. Which of the following amplifier circuit using junction transistor has the best gain?

   A. Common base
   B. Common emitter
   C. Common collector
   D. All have the same gain

5. The action of JFET in its equivalent circuit can best be represented as a_____________?

   A. Current controlled Current source
   B. Current controlled voltage source
   C. Voltage controlled voltage source
   D. voltage controlled current source

6. The bandwidth of an RF tuned amplifier is dependent on____________?

   A. Q –factor of the tuned o/p circuit
   B. Q –factor of the tuned i/p circuit
   C. Quiescent operating point
   D. Q-factor of the o/p and i/p circuits as well as quiescent operating point

7. Most of the linear ICs are based on the two-transistor differential amplifier because of its___________?

   A. input voltage dependent linear transfer characteristic
   B. high voltage gain
   C. high input resistance
   D. high CMRR

8. A differential amplifier is invariably used in the i/p stage of all OP-amps. This is done basically to provide the OP-amps with a very high_________?

   A. CMMR
   B. Bandwidth
   C. Slew rate
   D. Open-loop gain

9. Introducing a resistor in the emitter of a common amplifier stabilizes the dc operating point against variations in____________?

   A. Only the temperature
   B. only the β of the transistor
   C. Both Temperature & β
   D. None of the above

10. In a CB amplifier the maximum efficiency could be____________?

    A. 99%
    B. 85%
    C. 50%
    D. 25%