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Drawing Bode plots...

Discussion in 'Electronic Basics' started by David, Sep 24, 2007.

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  1. David

    David Guest

    I'm working through Sedra/Smith's Microelectronic Circuits and would like to
    find a tutorial on drawing Bode plots both by hand and using computer

    I did see several sites discussing using MATLAB to accomplish this so the
    by-hand methods are what I'm most interested in.
  2. You mean the familiar amplitude / frequency plot? Just get 3- or 4-cycle
    semi-logarithmic graph paper. If the nearest office-supply store doesn't
    have it, a university bookstore certainly will. Generating a logarithmic X
    scale by hand sounds really tedious. A ruler and the log function of a
    calculator? Pull the slide out of a slide rule so you can use the C scale
    for a ruler?
  3. David

    David Guest

    Well even with log paper I notice the plots usually have curves to them...
    Would you usually only plot the linear portions and then estimate the
  4. Eeyore

    Eeyore Guest

    What's the problem ? It's a graph with frequency on the x-axis and gain on the

    Typically, a logarithimic scale is used so as to display the wide range of
    values conveniently.

    In MATLAB etc, use the graphing tool.

  5. JeffM

    JeffM Guest

    That's so 20th Century.
    Welcome to the Computer Age.
    Simple technique:
    1) Plot as many data points as it takes
    to be confident you have the curve right.

    2) Connect the dots.
  6. Rich Webb

    Rich Webb Guest

    As alternatives to Matlab, take a look at:
    Scilab (free-as-in-beer; see their license regarding commercial use
    (summary: okay but don't modify it)) at,
    Octave (GNU) at, and
    OMatrix (not free but not too expensive) at

    IIRC, you can also do log-log and semilog plots with MS Excel and
    most/many other spreadsheets. (See OOo).

    My program of choice for this is Mathcad. I don't recommend it any
    more, based on the rather restrictive licensing scheme they went to.
    My old-but-working 2001i is just fine, thankyouverymuch.
  7. neon


    Oct 21, 2006
    First choose your cycles for the paper 1.2,3 whatever is needed then scale your X MAX TO MIN and go at it x >>>>>> y
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