BJT Small Signal Analysis: Common Emitter Fixed Bias and Voltage Divider Bias

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  • Опубликовано: 23 дек 2024

Комментарии • 75

  • @ALLABOUTELECTRONICS
    @ALLABOUTELECTRONICS  4 года назад +17

    The timestamps for the different topics covered in the video:
    1:00 Why a coupling capacitors are used in the Amplifier Circuit
    2:45 Steps to follow for the Small Signal Analysis
    4:35 Small Signal Analysis of CE Fixed Bias Circuit
    10:40 Small Signal Analysis (with output resistance)
    11:44 Small Signal Analysis of CE Voltage Divider Bias Circuit

    • @WalkWithKnowledge
      @WalkWithKnowledge 4 года назад

      plz..can you tell me which software you are using as explanation board..?
      I'm also started one channel I want one software like you are using ....!
      Thank you

    • @jineshks8271
      @jineshks8271 3 года назад

      Sir is this hybrid π model please help me...

    • @rutweakchacha1558
      @rutweakchacha1558 Год назад

      ​@@jineshks8271yess

  • @newtoninspired
    @newtoninspired 2 года назад +6

    Best Channel for Analog Electronics!

  • @uygarbaran8515
    @uygarbaran8515 3 года назад +15

    Thank you so much. You just saved me from hours of work.

  • @bijoyroychowdhuryprinon6768
    @bijoyroychowdhuryprinon6768 2 года назад +14

    salute from germany bro..

  • @mayurshah9131
    @mayurshah9131 4 года назад +5

    Excellent 👌 as usual

  • @sounikamandal
    @sounikamandal 3 месяца назад

    extremely helpful! Amazing explanation 🙏🙏

  • @ManuciansTrung
    @ManuciansTrung 4 года назад +6

    Can you explain more why is negative sign with the Voltage gain?
    Thank you

    • @ghousulhaq630
      @ghousulhaq630 3 года назад +1

      Due to out of phase at output

    • @ghousulhaq630
      @ghousulhaq630 3 года назад

      Dear when output is taken from collector then input signal in out of phase to the output (invert at output)

    • @RexxSchneider
      @RexxSchneider 2 года назад +1

      A small increase in the voltage applied to the base will produce an increase in the base current. That will produce an increase in the collector current. The increased collector current will produce a larger voltage across the collector resistor. But one end of that resistor is fixed at the supply voltage, so the voltage at the other end of the resistor must _decrease._ That is the collector of the transistor, and is the output of the stage.
      That shows that as the input voltage increases, the output voltage decreases. That is why we call it a negative gain.

  • @Hari-lg3fi
    @Hari-lg3fi 5 месяцев назад

    3:27 how this circuit will be fixed bias config? Base voltage is derived from Vcc. So can't it be voltage divider bias configuration sir?

  • @sangeet-sadhnakaraokeclub9175
    @sangeet-sadhnakaraokeclub9175 2 месяца назад

    Sir 6:16 i am confused about the resistors Rb and Rc how u placed them it seems odd

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  2 месяца назад

      Base resistor Rb is between base and ground. So, in AC equivalent circuit it is represented between base and emitter ( as emitter is ground).
      Similarly, collector resistor is between collector and ground terminal . So, in AC equivalent circuit, it is represented between collector and emitter terminal. I hope, it will clear your doubt.

  • @rajendrasiyag5306
    @rajendrasiyag5306 3 года назад +2

    Sir, I have observed that when there is a talk about approximation of anything, You call it so lightly that It is just for knowledge. Please tell that what exactly we will use during the question-solving side.
    I hope you will solve it.

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  3 года назад

      Many examples based on small signal analysis are also solved on the second channel. On this channel also, if you go through the playlist page, then you will find the BJT Solved example playlist. If you go through it, you will find many solved examples based on small signal analysis.

  • @teeggindarshannagappa8858
    @teeggindarshannagappa8858 Год назад

    Can you explain the condition at 16:30..? because the resultant of a parallel combination is always less then the least value

  • @kanishr5360
    @kanishr5360 4 года назад +1

    can you explain in which configuration the automatic street light using bc547 and ldr without relay

  • @poojashah6183
    @poojashah6183 4 года назад +3

    Bestest 👌🏻👌🏻

  • @mhsohan2769
    @mhsohan2769 9 месяцев назад

    As we consider capacitor is shorted for small signal analysis, does that mean small signal analysis is always done for high frequency application purpose?

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  9 месяцев назад

      No, here it is done for mid- band frequencies. But here it is assumed that the value of capacitor is selected such that, at the operating frequency , its reactance is very low and it can be assumed as a short circuit.

  • @yusufkhambaty930
    @yusufkhambaty930 2 года назад +1

    Sir why can’t we use vout/ iout for output impedance calculations

  • @nikolaynetsov6529
    @nikolaynetsov6529 4 года назад +1

    Why you put minus before gm in voltage gain? Vo=-gmVRc

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад +1

      In the equivalent circuit, if you see the current source gm*Vπ, it is flowing downwards.
      Applying KCL at the output, Io = - gm*Vπ.
      Therefore, Vo = -gm*Vπ*Rc
      And since Vin = Vπ.
      Vo / Vin or the voltage gain = -gm*Rc
      I hope it will clear your doubt.

    • @nikolaynetsov6529
      @nikolaynetsov6529 4 года назад

      @@ALLABOUTELECTRONICS Thank you for the answer

    • @user-fi3cd3ig6l
      @user-fi3cd3ig6l 4 года назад

      @@ALLABOUTELECTRONICS here how Io=-gm x vpi? Please answer me sir

    • @user-fi3cd3ig6l
      @user-fi3cd3ig6l 4 года назад

      @@ALLABOUTELECTRONICS how did minus sign come?

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад

      @@user-fi3cd3ig6l As I mentioned earlier, in the equivalent circuit, if you see the current source gm*Vπ is flowing downwards.
      Applying KCL at the output, Io = - gm*Vπ.
      Therefore, Vo = -gm*Vπ*Rc
      And since Vin = Vπ.
      Vo / Vin or the voltage gain = -gm*Rc
      I hope it will clear your doubt.

  • @deepikabirthare6622
    @deepikabirthare6622 4 года назад +1

    Can input impedance also be calculated as thevenin equivalent resistance as seen through input terminal?

    • @manitro337
      @manitro337 3 года назад

      Not quite sure, but I believe the small impedence resistance is ignored in comparison to the base/input resistance.

  • @WalkWithKnowledge
    @WalkWithKnowledge 4 года назад

    plz..can you tell me which software you are using as explanation board..?
    I'm also started one channel I want one software like you are using ....!
    Thank you

    • @vaibhavgiria5997
      @vaibhavgiria5997 4 года назад +6

      WILL A SALESMAN TELL YOU WHERE HE GETS THE GOODS FROM,,,,,,,,THEN YOU WILL ALSO BECOME A COMPETITOR AND STAND AGAINST HIM

    • @shivankitss8396
      @shivankitss8396 4 года назад

      @@vaibhavgiria5997 😂

  • @sarayushetty5678
    @sarayushetty5678 4 года назад +1

    When the voltage source is shorted how is resistance ignored, cant current flow through it??

  • @priyajitmondal6661
    @priyajitmondal6661 11 месяцев назад

    Thank you sir🙏🥺👍❤️

  • @parthasarker6121
    @parthasarker6121 2 года назад

    Loved this video

  • @abdxlive
    @abdxlive Год назад +2

    Apne Gain Ka Derivation With Early Effect Miss Kar Diya Hai Wahi Zaruri Tha 😪

  • @SuryaKJaya
    @SuryaKJaya 3 года назад

    Hai sir. I have a doubt. Weather AC analysis and small signal analysis are same?

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  3 года назад

      Yes

    • @RexxSchneider
      @RexxSchneider 2 года назад

      Not quite. The ac response is idealised so that we assume the changes in quiescent voltages and currents are small compared to their static values.
      You may have to consider sometimes the ac response of a circuit where the output swing is large, and then you will have to take into account, for example, the change in gm (and hence gain) as the collector current varies.

  • @beryyyllium
    @beryyyllium 4 года назад

    Sir, when does ro appear in the circuit?

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад

      When the early effect of BJT is also considered then output resistance should also be considered during the analysis.

  • @kontiimanalatit8987
    @kontiimanalatit8987 3 года назад

    The Ai of all common emitter circuits is equal to beta?

  • @farhanupaul
    @farhanupaul 4 года назад

    Can we use this model for high speed/ high frequency circuit?

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад +2

      At high frequency, other factors need to be considered as well. Will cover the high frequency model soon.

    • @arcticyt0219
      @arcticyt0219 Год назад +2

      @@ALLABOUTELECTRONICS Respected i thought this subject is harrd and i am going to fail in the sem exam but u saved my day just now started to study for the xam i have days of solid time to study ...i will get good marks with this tutorial ....need to say something sir i am also teaching to my friends .....THank U SO much Sir..................................

  • @danib5503
    @danib5503 2 года назад

    in the input impedance it is not the parallel combination of Rb and Rpi rather it is 1/parallel combination Rb and Rpi

    • @RexxSchneider
      @RexxSchneider 2 года назад +1

      No. The input impedance is the parallel combination of the resistors. It should be obvious that if those resistances increase, the input impedance must increase. Your formula would give a smaller answer if you made the resistances larger, and therefore must be wrong.

  • @susheelapatgar3640
    @susheelapatgar3640 4 года назад

    Thank u sir..it helps alot❤️👍

  • @nyarkofelicityserwaa3031
    @nyarkofelicityserwaa3031 10 месяцев назад +1

    thank you sir.

  • @حسيناحمدنجم-و6ي
    @حسيناحمدنجم-و6ي 4 года назад

    Hello can you help me in my research Who is talking about star-Delta transformation and its application for electric circuit containing impedances (complex values) similar.

  • @mailinhhoang3902
    @mailinhhoang3902 11 месяцев назад

    How to define the direction of io

  • @azizullookb4
    @azizullookb4 4 года назад

    are you sure that , you can see the generator as a open circuit? because it's not a indipendent generator...

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад

      I think you are talking about the equivalent circuit for finding the output resistance right !!

    • @ChannelHip
      @ChannelHip 4 года назад

      @@ALLABOUTELECTRONICS yes

    • @ChannelHip
      @ChannelHip 4 года назад

      LoOkB4U is my second account sir...

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад +1

      While calculating the output resistance, the input voltage source is considered as zero. And the dependent current source, gmVbe, depends on the input voltage. So, once input voltage and hence vbe is zero, the department current source will also become zero.
      I hope it will clear your doubt.

  • @ravikiranduvvuri8432
    @ravikiranduvvuri8432 4 месяца назад

    Thank you Sir.

  • @kavinnarayanan722
    @kavinnarayanan722 2 года назад

    Why don't u find Current gain?

  • @suryanarayana4355
    @suryanarayana4355 4 года назад

    Bro please put video about to explain the instrumentation amplifier

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад

      I have already made video on it.
      Here is the link: ruclips.net/video/pSctPegtZfc/видео.html

  • @sarayushetty5678
    @sarayushetty5678 4 года назад

    what is gm in the video, could someone plz explain this to me??

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  4 года назад +1

      gm is transconductance.

    • @RexxSchneider
      @RexxSchneider 2 года назад +1

      It is the rate of change of collector current as the base-emitter voltage changes. It increases as the collector current increases and is almost independent of the transistor used. It is found to be equal to the collector current divided by 25mV at room temperature.

  • @VishalSharma-ri3ih
    @VishalSharma-ri3ih 3 года назад

    This r0 existence is not cleared sir ...
    What is this place tell something

    • @ALLABOUTELECTRONICS
      @ALLABOUTELECTRONICS  3 года назад +1

      Please go through the video of early effect. It will get clear to you.
      Here is the link: ruclips.net/video/BOk501WULQs/видео.html

  • @arnavjain2212
    @arnavjain2212 Год назад +1

    jo jo yeh like karega, utna property aryan ke naam😆🤣🥰😝🥵🥵🏠🏠🏠
    1 like= 1 sq.ft
    🤭

  • @arashyusefi1889
    @arashyusefi1889 6 месяцев назад

    🙏 Thanks 🙏👍

  • @sarayushetty5678
    @sarayushetty5678 4 года назад +1

    When the voltage source is shorted how is resistance ignored, cant current flow through it??