Design cc-ce-cc amplifier

Discussion in 'Analog & Mixed-Signal Design' started by Jeongyun Kang, Nov 17, 2018.

  1. Jeongyun Kang

    Thread Starter New Member

    Nov 17, 2018
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    I'm going to design amplifier, requirement is that input impedance should be more than 20kohm, output impedance should be less than 50ohm, and voltage gain should be more than 200. So I'll make cc-ce-cc amplifier, but how can I choose transistor for each cc, ce, cc? And is it better to chooose transistor first and after that choose Rc, Re...and then R1, R2...etc? Or is there any other better way(order) to design it? Any guide will be appreciated. Thanks
     
  2. Bordodynov

    Well-Known Member

    May 20, 2015
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    You have chosen the wrong amplifier structure. I prefer to make the amplifier with a large gain and reduce the gain using negative feedback. This will increase the stability of the gain and reduce distortion. What you are proposing is a school approach. Well, try it. But you have to consider that there can be a more serious approach. See:
    Ampl12.png
     
  3. ScottWang

    Moderator

    Aug 23, 2012
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    @Bordodynov
    I just tested the asc file, but the left side of the graph table labeling as 0dB~20dB, they didn't like yours shown the voltage as 0V~360V.
     
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Move the mouse cursor at the Y-axis (the cursor turns into a ruler). Now, right mouse click to enter the menu and change the axis from Decibel to Linear.
     
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  5. ScottWang

    Moderator

    Aug 23, 2012
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    Thank you.
    I just want to try the original conditions as the posted graph table.
     
  6. Bordodynov

    Well-Known Member

    May 20, 2015
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    See
    Ampl12_.png Ampl12_tran.png
     
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  7. ArakelTheDragon

    Well-Known Member

    Nov 18, 2016
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    An opamp will be better I think. You will have a high current gain on the output. Why not use an OPAMP with a transistor on the output?
     
  8. Bordodynov

    Well-Known Member

    May 20, 2015
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    And what will you do if the signal source is very low impedance. In this case, of course, you can use an operational amplifier, but the goal is not this particular amplifier, but learning to build circuits. I push the idea that the amplifier electronics is not just a set of simple cascades, but an art. And that from the same number of transistors, using imagination and skill, you can extract more. Unfortunately this is not taught in school. It is also possible to vary the amplifiers using transistors of different conductivity and different types.
     
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  9. Bordodynov

    Well-Known Member

    May 20, 2015
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    Here is a more perfect scheme. It has more input resistance, less noise and a small output resistance.
    2018-11-20_09-08-45.png 2018-11-20_10-00-59.png
     
    absf likes this.
  10. Bordodynov

    Well-Known Member

    May 20, 2015
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    See CE-CC-CE:
    2018-11-21_08-47-37.png 2018-11-21_09-00-41.png
     
  11. hobbyist

    AAC Fanatic!

    Aug 10, 2008
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    Excellent reply, every thing you said is right on. Thank you.
     
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