OPTIMIZATION OF FIELD-EMISSION ARRAYS FOR INDUCTIVE OUTPUT AMPLIFIERS

In an inductive output amplifier, an emission gated electron beam indu ces high-frequency fields in an output circuit via displacement curren ts, not convection current. Emission gated electron beams experience s trong interactions when traversing a resonant or synchronous electroma gnetic field, and this strong interaction is responsible for both the interesting nonlinear physics and the attractive efficiency and compac tness of emission gated amplifiers. Field emission cathodes, due to th eir extremely low electron transit time and high transconductance, off er the opportunity to extend the advantages of emission gating into C and X bands. Design criteria for the joint optimization of the field e mission arrays (FEAs) structure and the rf input and output circuits o f inductive output amplifiers are presented. It is found that while ou tput circuits yielding net efficiencies of 50% or greater are well wit hin the state of the art, the gain is likely to be moderate (10-20 dB) . With today's FEA performance, a desirable operating regime is achiev able, yielding a new class of compact, highly efficient, and moderate gain power booster amplifiers. (C) 1996 American Vacuum Society.