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Class E amp in LTspice

Discussion in 'Radio and Communications' started by Mosaic, Aug 13, 2017.

  1. Mosaic

    Mosaic Well-Known Member

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    Hi All:
    I spent a few hours tweaking this using common parts to about 90% efficiency.
    It can do more power out with a > 36V supply. No AM modulation , yet.
    Xtal Sig gen & ClassE 140W.png
     

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  2. ci139

    ci139 Active Member

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    vhat wersion of LT Spice has idt() supported
    Function ::: Description
    ddt(f) ::: Derivative of f with respect to time
    d2dt(f) ::: Second derivative of f with respect to time
    idt(f) | sdt(f) ::: Integrate f in time
    ddx(f,x) ::: Derivative of f with respect to x
    d2dx(f,x) ::: Second derivative of f with respect to x
    idx(f,x) | sdx(f,x) ::: Integrate f in x
    extract from T-Spice 16 User Guide p.73,-4
     
  3. Mosaic

    Mosaic Well-Known Member

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    I am still on LTspice version 4.2 if that's the question.
     
  4. dave

    Dave New Member

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  5. ci139

    ci139 Active Member

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    alec just indirect answered this in http://www.electro-tech-online.com/threads/spice-help.151665/ (((still they're not directly avail. on the plot panel - which caused this question)))
     
  6. Mosaic

    Mosaic Well-Known Member

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    I observed that increasing the idt period to 60uSec gave better results (more stable ) in this sim.
    FYI, some improvements to the performance can be had by:

    Tuning the output, similar eff%
    590n inductor vs 3.3n cap is one option, 2nd harmonic => 23dBr down, 158W out
    1975n inductor vs 800p cap is another => 34dBr down (2nd harmonic) @172W out
    2500n inductor vs 625p = 2nd harmonic => 36dBr down, +/- 4pf tuning range, 165W out
    3000n vs 515pf, 2nd harmonic 37dBr down
    4000n vs 382p, 2nd harmonic 40dBr down now, +/- 2 pf cap tuning can vary amplitude & eff% a lot.
    5000n vs 305pf, 2nd harmonic 43dB down, but capacitor tuning is +/- 1 pf now
     
  7. ci139

    ci139 Active Member

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    is it idt period or simulation minimum timestep coz the simulation becomes slower and more "accurate" (to simulation) if you dec. the least

    however the fine tunings in real world might have no apprpopriate effect (my Spice experience with power supply simulations is that there is no gain miracles e.g. most supply types (in practise) become stable by biasing the power switch input by 4mA or more - sufficiently for real life Ic-degraded ß(HFE) to keep the collector current flowing at above the moderate loads e.c. - e.g. you have to sledge hammer the circuit to and stay to mode it suppose to be ....)
     
  8. Mosaic

    Mosaic Well-Known Member

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    Y'know a class E RF amp might make for an efficient SMPS design approach given the fixed frequency tuning and Mhz range switching.
    Certainly possible for a boost application.
     
  9. ci139

    ci139 Active Member

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    and the way around i guess i even seen a switched power amp circuit . . . https://en.wikipedia.org/wiki/Class-D_amplifier -- ! surprise ☁̷̸̟☠♨☦ :lurking:sh¡t . . . i'm not an audio guy just got some old chips i thought to convert for small-power amps for evening-/night-/sleep time listening (count the sheep alternative) -- too many things undone so i always don't like to go to sleep . . .
     

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