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Class E amp in LTspice


Active Member
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


Well-Known Member
Thread starter #5
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


Active Member
I observed that increasing the idt period to 60uSec
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 ....)


Well-Known Member
Thread starter #7
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.


Active Member
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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