feedback topologies?

Discussion in 'Homework Help' started by majinboy, Jun 12, 2006.

  1. majinboy

    Thread Starter New Member

    Jun 12, 2006
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    Hi people,
    My first post here, I have some queries regarding feedback topologies. Namely, how on earth do you identify wether a circuit contains shunt-shunt, series-shunt etc. topology?

    Also, how do you determine which circuit element/s are a part of the feedback network?

    thanks,
    Alex.
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    1,723
    I can help with the second part of your question. From Vacuum Tubes, to Bipolar Junction Transistors, to Field Effect Transistors there are three possible amplifier configurations.

    Common Cathode ≡ Common Emitter ≡ Common Source
    Common Grid ≡ Common Base ≡ Common Gate
    Common Plate = Common Collector ≡ Common Drain

    In this context the word "common" means that that node of the active device is common to both the input circuit and the output circuit. Once you have identified the common node you can find the input node and the output node.

    In the case of a Bipolar Junction Transistor
    Common Emitter has input on the base and output on the collector
    Common Base has input on the emitter and output on the collector
    Common Collector has input on the base and output on the emitter

    Similarly for tubes and FETs. Unlike semiconductor devices tubes may have extra grids(tetrodes and pentodes).

    One more note, the Common (Collector, Plate, and Drain) circuits are often called
    (Emitter, Cathode, and Source) Follower because the indicated output node follows the input signal.

    The feedback elements take a portion of the output signal and bring it back to the input.

    I'll let someone else answer part one of your question.
     
  3. mozikluv

    AAC Fanatic!

    Jan 22, 2004
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    hi alex,

    i believe i already have answered that same query way back. just can't remember when, pls. try to check my previous posts.

    mozikluv
     
  4. mozikluv

    AAC Fanatic!

    Jan 22, 2004
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    hi alex,

    am not sure if you found my previous post.

    anyway here's the revised version which now includes the transistor circuit.
     
  5. majinboy

    Thread Starter New Member

    Jun 12, 2006
    2
    0
    Hi mozikluv,
    I hadn't found your previous post yet as today is first time i have been back on these forums. Thanks for replying.

    Also thanks to Papabravo for replying too. I will study these and will be back with more questions soon.
     
  6. mozikluv

    AAC Fanatic!

    Jan 22, 2004
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    am reattaching the feedback topologies documents which got lost during the changeover.

    moz
     
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