Neets Module 8 Assignment 1

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Neets Module 8 Assignment 1
2012-08-09 16:30:54

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  1. What is amplification?
    Amplification is the control of an output signal by an input signal so that the output signal has some (or all) of the characteristics of the input signal. The output signal is generally larger than the input signal in terms of voltage, current, or power.
  2. Does an amplifier actually change an input signal? Why or why not?
    No, the input signal is unchanged, the output signal is controlled by the input signal but does not effect the actual input signal.
  3. Why do electronic devices use amplifiers?
    To amplify the input signal to a usable level.
  4. In what two ways are amplifiers classified?
    By function and frequency response.
  5. What type of amplifier would be used to drive the speaker system of a record player?
    An audio power amplifier.
  6. What type of amplifier would be used to amplify the signal from a radio antenna?
    An RF voltage amplifier.
  7. What determines the class of operation of an amplifier?
    The amount of time (in relation to the input signal) in which current flows in the output circuit.
  8. What are the four classes of operation of a transistor amplifier?
    • A
    • AB
    • B
    • C
  9. If the output of a circuit needs to be a complete representation of one-half of the input signal, what class of operation is indicated?
    Class B operation.
  10. Why is class C operation more efficient than class A operation?
    The amplifier operates (and therefore uses power) for less time in class C than in class A.
  11. What class of operation has the highest fidelity?
    Class A operation.
  12. What is the purpose of an amplifier-coupling network?
    To transfer energy (a signal) from one stage to another.
  13. What are four methods of coupling amplifier stages?
    • Direct
    • RC
    • Impedance
    • Transformer coupling.
  14. What is the most common form of coupling?
    RC coupling.
  15. What type coupling is usually used to couple the output from a power amplifier?
    Transformer coupling.
  16. What type coupling would be most useful for an audio amplifier between the first and second stages?
    RC coupling
  17. What type of coupling is most effective at high frequencies?
    Impedance coupling.
  18. What impedance relationship between the output of one circuit and the input of another circuit will provide the maximum power transfer?
    Equal impedance.
  19. If maximum current is desired at the input to a circuit, should the input impedance of that circuit be lower than, equal to, or higher than the output impedance of the previous stage?
    Lower than.
  20. What are the input- and output-impedance characteristics of the three transistor configurations?
    Common emitter-medium input, medium output; common base-low input, high output; common collector-high input, low output.
  21. What transistor circuit configuration should be used to match a high output impedance to a low input impedance?
    Common collector.
  22. What type of coupling is most useful for impedance matching?
    Transformer coupling.
  23. What is feedback?
    The process of coupling a portion of the output of a circuit back to the circuit input.
  24. What are the two types of feedback?
    Positive and negative or regenerative and degenerative.
  25. What type feedback provides increased amplitude output signals?
    Positive (regenerative) feedback.
  26. What type feedback provides the best fidelity?
    Negative (degenerative) feedback.
  27. If the feedback signal is out of phase with the input signal, what type feedback is provided?
    Negative (degenerative) feedback.
  28. What type feedback is provided by an unbypassed emitter resistor in a common-emitter transistor amplifier?
    Negative (degenerative) feedback.
  29. What is a phase splitter?
    A device that provides two output signals that differ in phase from a single input signal.
  30. What is one use for a splitter?
    A phase splitter is used to provide the input signals to a push-pull amplifier.
  31. What is a common use for a push-pull amplifier?
    A push-pull amplifier is used when high power output and good fidelity are needed.
  32. What is the advantage of a push-pull amplifier?
    A push-pull amplifier provides more gain than a single transistor amplifier.
  33. What class of operation can be used with a push-pull amplifier to provide good fidelity output signals?
    • Class A
    • Class AB
    • Class B