Resistive arc protection for field-emitter-array cold cathodes used in X-band inductive output amplifiers

Field emitter arrays (FEAs) can provide advantages over gridded thermionic emitters when used as cold cathodes in inductive output amplifier (IOA) tub es. However, they are prone to destructive arcing currents that reduce thei r lifetime. Display developers have alleviated this problem by means of int egral resistors formed in series with the emitting tips, but the resistive layers as currently used preclude gate modulation at X-band frequencies. By using a vertical instead of a lateral resistor, the layer can act as its o wn bypass capacitor under high frequency operation. An analysis of the effe ct of the resistive layer on rf performance is given. It is shown that redu cing the thickness of the layer results in an acceptable bypass capacitor v alue, while still maintaining sufficient are current protection. This is co nfirmed by means of an analytical model and SPICE simulation of a resistive ly protected FEA in an IOA configuration. FEAs fabricated with such resisti ve layers showed improvements in lifetime under de test conditions. (C) 199 9 American Vacuum Society. [S0734-211X(99)05802-3].