Large‐signal and small‐signal electronic equivalent circuits for a field electron emitter

Abstract

Large-signal and small-signal electronic equivalent circuits are developed to describe signal generation by a field electron emitter, with and without a ballast resistor. It is shown that different small-signal equivalent circuits are needed for the cases where a small alternating voltage variation is applied and where the tunneling process is directly modulated, e.g. by directing a laser at the field emitter. The role of circuit resistances and of the parasitic capacitance between the emitter and its surroundings is crucially different in the two cases, with low-pass filter behaviour exhibited in the first case and high-pass filter behaviour in the second. Some consequences for the technical use of a field electron emitter as a non-linear device are discussed, particularly in applications that involve laser-assisted field electron emission and in the context of testing field emission tubes.

Field emission - based many-valued processing using carbon nanotube controlled switches - Part 1: Fundamentals

“…6. It was observed earlier that field emission tube itself behaves like a low-pass filter [27]. Equation (7a) shows that the increase in the field emission current (I Δ ) acts as a current source, and it can be shown that when a square-wave current source is fed to a parallel R-C circuit, the voltage across the resistor has a saw-tooth waveform with a peak-to-peak value of: V pp = R I Δ (1 -e -1/2f ) / (1 + e -1/2f ) (8) Fig.…”

“…Rigorous quantum simulations of laser-assisted field emission were performed which showed that the radiation from two lasers increases the DC current (optical rectification) and also causes harmonics and mixing terms with frequencies (n 1 f 1 + n 2 f 2 ), where f 1 and f 2 are the frequencies of the lasers and the integers n 1 and n 2 may be positive, zero or negative. However, the high-frequency terms are not seen in measurements of the current that passes through a field emission tube because the tube itself acts as a low-pass filter [27]. Antennas and transmission lines on field emitters have been made to couple microwave output power at the difference frequency (f 1 -f 2 ) [1,26], but these techniques were not implemented in the utilized tubes shown in Fig.…”

“…Instead, the spectrum of the field emission current was determined when transformers were used to superimpose low-frequency voltages on the applied static field with f 1 = 1.67 kHz and f 2 = 1.10 kHz. These frequencies were chosen [27] because they are low enough that the effects of the capacitances and inductances within the tubes may be neglected.…”

“…Carbon nanotubes are excellent field emitters [9,10,13,16,19,29,36,38,39,41] and facilitate the miniaturization of electronic devices [3,4,[6][7][8][9]15,17,24,[26][27][28]30,33,35,36,41]. Furthermore, the kinetic inductance of CNT causes them to be high impedance (approximately 5 k) transmission lines [28], and has shown that this effect can be used for the efficient broadband matching to the high impedance that is inherent in field emission.…”

Field emission - based many-valued processing using carbon nanotube controlled switches - Part 2: Architecture effectuation

“…It is also shown that the tip will withstand applied static fields as high as 9 V/nm, so that incident laser radiation with comparable field strengths could produce a bright source of microwave or THz radiation. Carbon nanotubes are excellent field emitters [9,10,13,16,19,29,36,38,39,41] and facilitate the miniaturization of electronic devices [3,4,[6][7][8][9]15,17,24,[26][27][28]30,33,35,36,41]. Furthermore, the kinetic inductance of CNT causes them to be high impedance (approximately 5 k) transmission lines [28], and had shown that this effect can be used for efficient broadband matching to the high impedance that is inherent in field emission.…”