Cascode configuration

Discussion in 'General Electronics Chat' started by mnada, Aug 4, 2012.

  1. mnada

    Thread Starter New Member

    Apr 5, 2012
    26
    0
    Hi, In the cascode topic there is a figure that confused me, it's this one
    [​IMG]

    Is this ( fig on right ) really common-base? It looks to me as a common emitter. If it's really a common base configuration, please give me a guide to identify the amplifier configuration type. One more thing I want to know what is the purpose of the capacitor C2 in the left fig. thanks
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    The cascode amp comprises two parts. The input is indeed a common emitter stage [Q3] but with a common base [Q2] collector load - rather than a simple resistive load. C2 bypasses Q2 base to ground forming the common base [AC] connection.
     
    mnada likes this.
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    656
    The circuit on the right is mis-labeled. It is actually a common-emitter stage, as indicated in the text below it.


    Q2 is the common-base stage. The input is the emitter, receiving the current from Q3. The base is AC-grounded through C2.
     
    mnada likes this.
  4. mnada

    Thread Starter New Member

    Apr 5, 2012
    26
    0
    Thank, does this mean that the caption under the right figure should be common-emitter instead of common-base?
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    656
    That makes the most sense. I don't see much point in comparing cascode with common-base.
     
    Last edited: Aug 4, 2012
    mnada likes this.
  6. mnada

    Thread Starter New Member

    Apr 5, 2012
    26
    0
    Is Nutmeg available to download for windows? can you please tell the link
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,344
    mnada likes this.
  8. mnada

    Thread Starter New Member

    Apr 5, 2012
    26
    0
    I can live with msdos version can you advice the link
     
  9. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,344
Loading...