Development of GaAs Gunn Diodes and Their Applications to Frequency Modulated Continuous Wave Radar

Abstract

In this work, we have designed and fabricated the GaAs Gunn diodes for a 94 GHz waveguide voltage controlled oscillator (VCO) which is one of the important parts in a frequency modulated continuous wave (FMCW) radar application. For fabrication of the high power GaAs Gunn diodes, we adopted a graded gap injector which enhances the output power and conversion efficiency by effectively removing the dead-zone. We have measured RF characteristics of the fabricated GaAs Gunn diodes. The operating current, oscillation frequency, and output power of the fabricated GaAs Gunn diodes are presented as a function of the anode diameters. The operating current increases with anode diameters, whereas the oscillation frequency decreases. The higher oscillation frequency was obtained from 60 µm anode diameters of the fabricated Gunn GaAs diodes and higher power was obtained from 68 µm. Also, for application of the 94 GHz FMCW radar system, we have fabricated the 94 GHz waveguide VCO. From the fabricated GaAs Gunn diodes of anode diameter of 60 µm, we have obtained the improved VCO performance.

Origins of Negative Differential Resistance in N-doped ZnO Nano-ribbons: Ab-initio Investigation

“…For instance GaAs-based Gunn diodes are made with frequencies up to 200 GHz, whereas GaN-based ones can reach up to 3 THz 37 . Furthermore, both Esaki and Gunn diodes use NDR for applications as oscillators, amplifiers, frequency converters, and detectors 38,39 .…”

“…The methods are incorporated into the code of Atomistic Tool-Kit (ATK) 51 . While debates about the origins and mechanisms yielding NDR are still active, the so-far achieved findings can be categorized into three possible groups: (i) Two-valley model has been successful to explain the Gunn effect as stated above 36–39 ; (ii) Suppression of resonant band/channel at Fermi level which is the case of molecular junctions 40–45 . Using ATK, Fan and coworkers 52 demonstrated that a single C 60 -molecule in a nanodevice can yield NDR controllable by shape deformation of molecule and specifically its interactions with the leads.…”

Characteristics of GaAs varactor diode with hyperabrupt doping profile

“…For applications such as vehicle collision avoidance systems and military radar sensors, frequency modulated continuous wave (FMCW) radar technology operating in the W‐band is an excellent solution. The improved performance of FMCW radar system necessitates the development of a waveguide VCO with high linearity and a wide bandwidth, which in turn demands the need for a high‐performance varactor diode . One very attractive feature of varactor diodes is their ability to electronically tune a given circuit to different frequencies by changing the reverse‐bias conditions .…”