BJT Circuit Analysis: The CASCODE Amplifier (Pt 1) (066g1)

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  • Опубліковано 31 гру 2024

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  • @fabiotrevisan8922
    @fabiotrevisan8922 5 місяців тому +2

    Very nice video and explanation.
    Your narration is also astoundingly clear in the way how you emphasize the important passages and such.
    Very well done!

    • @eie_for_you
      @eie_for_you  5 місяців тому

      Thank you so very much! I really appreciate the encouragement! 🙂

  • @acestudioscouk-Ace-G0ACE
    @acestudioscouk-Ace-G0ACE 5 місяців тому +3

    Thanks for making this video, the great thing about UA-cam is that you can re-watch until you have learnt and understood everything taught.

    • @eie_for_you
      @eie_for_you  5 місяців тому

      True that! And I've done that many times. Also, I've provided time markers in the description if you need to jump to a specific place. just click on the marker and you are there. 🙂

    • @acestudioscouk-Ace-G0ACE
      @acestudioscouk-Ace-G0ACE 5 місяців тому

      @@eie_for_you Time markers are a great help, thank-you!👍

    • @eie_for_you
      @eie_for_you  5 місяців тому

      @@acestudioscouk-Ace-G0ACE You are very welcome! 🙂

  • @Wil_Bloodworth
    @Wil_Bloodworth 5 місяців тому +3

    Excellent video. Thank you very much. I look forward to the follow-up one. God bless!

  • @WECB640
    @WECB640 5 місяців тому

    Once again, this was exceptional. Thank you Ralph for all your excellent teachings. 73

    • @eie_for_you
      @eie_for_you  5 місяців тому

      You are very welcome! 🙂

  • @Simon-mz7sf
    @Simon-mz7sf 5 місяців тому +1

    Great tutorial Ralph. Thankyou

    • @eie_for_you
      @eie_for_you  5 місяців тому

      Thank you and you are very welcome! 🙂

  • @fullwaverecked
    @fullwaverecked 5 місяців тому +3

    Damn Ralph, I'm 61 and today is the first time I finally figured out that my brain is like an ice cream cone. No matter how many times you melt it, I can always pull another out of the freezer... Thank you for doing that thang that you do.

    • @eie_for_you
      @eie_for_you  5 місяців тому

      You are very welcome, my friend! 🙂

  • @W1RMD
    @W1RMD 5 місяців тому

    Perfect! Thanks for sharing and take care.

    • @eie_for_you
      @eie_for_you  5 місяців тому +1

      You are very welcome, my friend! 🙂

  • @brjplummer9415
    @brjplummer9415 5 місяців тому +3

    This circuit was commonly used for the RF amplifyer in TV tuners connecting to the antenna and valves were used.

    • @eie_for_you
      @eie_for_you  5 місяців тому

      I would that there is a LOT less inter-element capacitance with a vacuum tube. Thus the higher frequency capability. 🙂

  • @ornithopterindia
    @ornithopterindia 5 місяців тому

    👍Thank you sir.

    • @eie_for_you
      @eie_for_you  5 місяців тому

      You are very welcome! 🙂

  • @fullwaverecked
    @fullwaverecked 5 місяців тому +1

    BTW, i always do the thumbs up before I watch the video, but i often forget to do it with your fine vids. Like devouring a fine steak and someone asking if i want steaksouse... Too busy doing Num Num Num....

    • @eie_for_you
      @eie_for_you  5 місяців тому +1

      Now that is a very interesting analogy! Thank you for the encouragement! 🙂

  • @kensmith5694
    @kensmith5694 5 місяців тому +1

    Note for new players:
    The names of the capacitances vary depending on what school you went to. There isn't really a standard naming in that form.
    I use Ceb and Ccb as the names.
    It is also easier to type.
    Also:
    If you put a resistor in series with Ce (on his design) to lower gain, it is also good to change where Cb hooks.
    Basically you put the resistor on the ground end of Ce and run Cb to that spot also.
    This gives you a higher input impedance.

    • @eie_for_you
      @eie_for_you  4 місяці тому

      WOW! I can't believe that it took me so long to notice this comment! My apologies! :-(
      In my next video I am going to be going through this whole process of a reduced gain version of the CASCODE amplifier. There are two basic methods to consider, one being to split the emitter resistor with the lower half being bypassed; this reduces the gain of the common-emitter portion of the circuit. The other is to design around this on the common-base part, setting the Rc to provide the needed gain there. :-)

    • @kensmith5694
      @kensmith5694 4 місяці тому

      @@eie_for_you
      As I said, my comment was targetting the "new players" who may be watching your video to understand the idea.
      A video of a version with well known gain (no temp co) would be a nice second one.
      I think a resistor in the ground end of Ce is better than splitting the emitter resistor. As a first step in the design it is no difference with the series splitting method but it does allow the Cb thing I suggested. If you then also bring the Rb3 over to that point, you can bootstrap out the loading the bias circuits put on the input. This can give you a really high impedance and a well known voltage gain.

    • @eie_for_you
      @eie_for_you  4 місяці тому

      @@kensmith5694 Cool!
      Yeah, the advantage of splitting the emitter resistor to control the overall gain does have the decided advantage of a higher input impedance. 🙂

  • @RaymondLau-u7x
    @RaymondLau-u7x 5 місяців тому

    I think I might have to watch this 2 or 3 times before it sinks in.

    • @eie_for_you
      @eie_for_you  5 місяців тому

      I know the feeling! There are some things in electronics that take a bit of work to understand what is going on. 🙂

  • @byronwatkins2565
    @byronwatkins2565 5 місяців тому

    Actually, the gain of the common emitter amplifier, Rc/Re, might be significantly less than 1. Cascode also greatly reduces the Early effect.

    • @eie_for_you
      @eie_for_you  5 місяців тому +1

      But, in its interaction with the common-base, it does approximate a gain of 1, in practice. This is how it was explained to us in engineering school and in the texts I reviewed to create this video. 🙂

    • @byronwatkins2565
      @byronwatkins2565 5 місяців тому +1

      @@eie_for_you With no emitter degeneration resistance, Rc=re for the top resistor and Re=re for the bottom resistor. In this case, the voltage gain is very close to 1, but the combined gain is not well-defined and varies greatly with signal level. Assuming gain=2 does consider the worst case for the Miller effect and is therefore not a bad strategy even when using emitter degeneration resistance to stabilize the gain..

    • @eie_for_you
      @eie_for_you  5 місяців тому

      @@byronwatkins2565 I hear ya! 🙂

  • @davidluther3955
    @davidluther3955 5 місяців тому

    INTREGUING!I HOPE I DO NOT GET LOST WITH THE DESIGHN EQUATIONS.AT ABOUT WHAT FREQUENCY DOES THE MILLER CAPACITANCE BECOME A PROBLEM?

    • @eie_for_you
      @eie_for_you  5 місяців тому +2

      Well, the frequency limitations depend entirely on the specific transistor being used. It also depends on the gain you set it up for. You can control the overall gain by splitting the emitter resistor, the bottom one is bypassed. The top one works together with the collector resistor to set the overall gain. The lower the set gain, the broader the frequency response. All of this will be covered in the next video where I go through the design and then we will see the results of the design including the "limited gain" version. 🙂

    • @andymouse
      @andymouse 5 місяців тому

      Audio.

    • @eie_for_you
      @eie_for_you  5 місяців тому +2

      @@andymouse Actually ... the main purpose was to extend the frequency response out far enough to be used as video amplifiers. This puts it well up into the MHz range. But, the actual extent depends entirely on the specific transistor you are using and the amount of actual gain you design into the amplifier. 🙂

    • @kensmith5694
      @kensmith5694 5 місяців тому +1

      It is going to also depend on your signal source's impedance. Remember that "Miller capacitance" is the gain of the stage times the Collector-base capacitance. This capacitor works against you signal source's resistance in
      F=1/(2*pi*R*C)
      If you make a stage with a gain of 100 using a transistor with a 1pF collector to base, you get 101pF seen at the input from that.
      If your signal has a 200K impedance, the result will be good enough for voice but not hifi.