Power amplifier class E & F

[sinato]

the load termination for class E is different from that of class F and we use port adapter in cadence to determine the optimum load for the power amplifier by varying reflection coefficient .I feel now that the port adapter is the one which determine the class of the amplifier not me as it decides which load should we use

 

[D.A.(Tony)Stewart]

Class F amp in microwave Design involves a matching network design at the fundamental frequency and load harmonics. The common practice is to present a short circuit at the even order harmonics, and an open circuit at the odd order harmonic. This 2nd and 3rd harmonic is usually adequate. Thus the gate voltage will be out of phase with drain current on harmonics. and 75 to 80% efficiency may be possible.

The Class E amp is more a time domain filter design with a switched inductive current source into two resonant tank circuits. This current is commutated between the capacitor and switch. When the switch is closed, the voltage is forced to zero, fixing the capacitor’s charge, thus forcing the current through the switch. When the switch is open, the capacitor must conduct the current. By appropriately adjusting the amplitude and phase of the sinusoidal component of the current, a solution is found with zero capacitor charge just prior to turn on. This leaves an additional degree of freedom, which is typically used to set the capacitor current to zero at turn on. This results in a switching waveform with zero voltage (no capacitor charge) and zero voltage slope (no capacitor current) at turn on, conditions now known as the class-E switching conditions.

Ref Class E

 

[sinato]

1st thanks for your reply , what I am trying to say that for class E i should choose the load network so as to let the voltage of the cap discharge completely before the switch turns on so I am going to use the port adapter (varying load) to determine this optimum load while in class F although I should choose load terminations at different harmonics but I will also use the port adapter in the same way ...... My problem may be that I don't know how to choose the load termination at different harmonics using port adapter