Component Calcs for ClassE Single-Ended

[DMOD]

If you don't use spreadsheets and use MatLab, here is a calc listing for a ClassE amp. If you don't have MatLab, you can use each step as a value for hand calculations, or use them in a spreadsheet. This listing includes FET output capacitance and the RDSon. In this calculation, Cshuntprime has to be greater than the FET output capacitance.

% Component Calcs for Switchmode RF Power Amp ClassE using an "L" harmonic filter
%
Coss = 300e-12
Rdson = 0.7
FH = 3.955e6
FL = 3.5e6
BW = FH - FL
Fc = 0.5*BW + FL
Q = Fc/BW
VDv = 100
Vsquared = VDv^2
Power = 350
Rload = (0.32*Vsquared)/(Power - (1.5*Rdson))
POVDv = Power/VDv
pi = 355/113
Omega = 2*pi*Fc
OmegaR = Omega*Rload
Omegasquared = Omega^2
X = 1.15*Rload
QR = Q*Rload
RoverOmega = Rload/Omega
Cshuntprime = (0.212/OmegaR)
Cdrainshunt = Cshuntprime - Coss
CseriesTune = .685/(Omega*(QR - X))
CshuntLoading = CseriesTune*5.5
LseriesResonant = 1/(Omegasquared*CseriesTune)
Lrfc = 50*RoverOmega % multiply by 0.283 for Push-Pull Operation with a center tapped output transformer
Vpeakdrain = 3.67*VDv
Isupplyavg = 1.1*POVDv
Idrainmax = 2.647*Isupplyavg
%

Computed values for 80 meters and a 350 Watt carrier were rounded up:

Fc = 3.728 Mhz
Q = 8.2
Power = 350 Watts
Rload = 9.2 Ohms
Cdrainshunt = 687 pF
CseriesTune = 453 pF
CshuntLoading = 2,491 pF
LseriesResonant = 4.0 uH
Lrfc = 20 uH
Vpeakdrain = 367 Volts
Isupplyavg = 3.9 Amps
Idrainmax = 10.2 Amps

Cheers - AC0OB

[steve_qix]

Also, you can check this URL. There are a number of good design tools there for class E.

http://www.classeradio.com/tools/tools.htm

Regards,

Steve