Optimal load impedance for class E PA

Hi all,

I have a question about class E PA design.
When designing a class E PA, it's always suggested that we choose a optimum
load impedance according to Z= 0.28015/(ω*Cs) * exp( j 49.0524 degree).
My question is do we need to consider the stability of the amplifier.
It seems that if we just use the equation to design the load impedance, we can't make sure that impedance will make the amplifier stable?
Can any one kindly clear my confusion?
Thank you very much!

Due to the switching behavior Class E are rather power converters than amplifiers, when the output voltage is entirely determined by the supply voltage and load network elements. In this case the stability shouldn?t be a problem but you have to look for the stability of the entire circuit, when usually the Class E final stage uses in the front a voltage amplifier.