Field emission triodes

Triode RF amplifier structures using field emission cathodes have been investigated from both the theoretical and experimental viewpoint. The physically large experimental structure used and the theoretical calculations for that structure are described. The agreement between theory and experiment for both DC and AC measurements is shown to be very good. The theoretical circuit modeling has produced information useful in work on higher-frequency operation. A RF voltage gain of about 11 dB has been measured at low frequencies, dropping to 0 dB at 200 kHz; the cathode had a transconductance of only 38 μS. Model calculations on the large structure used show operation to about 2 MHz with a more typical transconductance of 380 μS for a 1000-cone field emission cathode