Broadband traveling wave amplifier with an input stripline cathode and an output stripline anode

A broadband traveling wave amplifier which comprises a target anode and electron gun means for bombarding said anode with an electron beam having an amplitude proportional to the amplitude of an input signal to be amplified, characterized in that the electron gun means comprises:

• a cold cathode, which is configured as an input strip transmission line, or input stripline, having an electron emitting surface, comprising a semiconductor heterojunction formed by a first, N type, NEA semiconductor material having an indirect bandgap and a second NEA semiconductor material having a direct bandgap, wherein the indirect bandgap is wider than the direct bandgap, and the electron emitting surface is an outer surface of the direct bandgap NEA semiconductor material opposite the heterojunction, wherein the first NEA semiconductor material comprises cubic boron nitride (cBN), and the second NEA semiconductor material comprises aluminum nitride (AlN);
• and
• a modulation structure for modulating the electron beam with said input signal, said modulation structure comprising an adjacent electrically conductive control grid spaced from and extending over said electron emitting surface, wherein the signal to be amplified is applied between the N type NEA semiconductor material and the control grid;
• and
• said anode is configured as an output strip transmission line spaced from and extending parallel to the input stripline cathode, said output stripline anode having an electron bombarded surface facing the electron emitting surface of the input stripline cathode, and said output stripline anode exhibiting a phase velocity equal to the phase velocity of the input stripline cathode.

A broadband, traveling wave, push pull, amplifier assembly, which comprises:

• first and second broadband traveling wave amplifiers, having essentially identical characteristics, each amplifier comprising a target anode and electron gun means for bombarding said anode with an electron beam having an amplitude proportional to the amplitude of an input signal, the two electron guns means being supplied with opposite polarities of an alternating input signal to be amplified,
• wherein said electron gun means comprises (1) a cold cathode which includes semiconductor material exhibiting negative electron affinity (NEA) and which is configured as an input strip transmission line, or input stripline, having an electron emitting surface, and (2) a modulation structure for modulating the density of the electrons emitted from said electron emitting surface with said input signal to generate said electron beam, and
• wherein said anode is configured as an output strip transmission line spaced from and extending parallel to the input stripline cathode, said output stripline anode having an electron bombarded surface facing the electron emitting surface of the input stripline cathode, and said output stripline anode exhibiting a phase velocity equal to the phase velocity of the input stripline cathode;
• and
• an adjustable d.c. bias voltage supply means for providing a d.c. positive bias to the modulation structure relative to the input stripline cathode of both electron gun means, to preclude any electron emission for zero or negative potentials of the alternating input signal to be amplified;
• wherein the two output stripline anodes are connected in an output circuit such that said amplifier assembly operates in a push-pull mode.