Field emitter array development for gigahertz operation

Progress is reported in a program to develop a GHz vacuum tube power amplifier using a modulated linear array of Spindt-type field emission cathodes for the electron source. Techniques developed in this program have enabled arrays of up to 500 tips per nm to be fabricated with a capacitance of 0.08 pF per mm, and a transconductance of 0.8 m Siemens per tip at an emission level of 40 mA per tip. Modulation of a test device with a 1.25 m long array at frequencies approaching 1 GHz using microstrip line couplers has been demonstrated. Methods for improving the performance are discussed.<>