Slot-Ring Multiport Driven Antenna with Improved Airside Radiation for Terahertz Communications

A slot-ring multiport driven (MPD) antenna is evaluated for operation in the terahertz band with emphasis on air-side radiation on a thick Indium Phosphide (InP) substrate. Geometrical modification to the known slot-ring are made by employing a circular outer ground and a backing ground plane to focus the radiation in the airside direction. Optimization of the modified structure is made to find the optimal size of the upper ground plane. The optimal design achieves maximum directivity of 10.8 dB which is an improvement of 3 dB from the original design. Moreover, the radiation is directed in the airside direction with a front-to-back lobe ratio of 14 dB. The slot-ring antenna design is verified by fabrication at 5 GHz and achieves 10.2 dB directivity

THz Electronics for Data Centre Wireless Links - the TERAPOD Project

This paper presents an overview of the terahertz (THz) resonant tunneling diode (RTD) technology that will be used as one of the approaches towards wireless data centres as envisioned on the eU H2020 TERAPOD project. We show an example 480 gm × 680 gm THz source chip at 300 GHz employing a 4 gm × 4 gm RTD device with 0.15 mW output power. We also show a basic laboratory wireless setup with this device in which up to 2.5 Gbps (limited by equipment) was demonstrated

Resonant tunnelling diode based high speed optoelectronic transmitters

Resonant tunneling diode (RTD) integration with photo detector (PD) from epi-layer design shows great potential for combining terahertz (THz) RTD electronic source with high speed optical modulation. With an optimized layer structure, the RTD-PD presented in the paper shows high stationary responsivity of 5 A/W at 1310 nm wavelength. High power microwave/mm-wave RTD-PD optoelectronic oscillators are proposed. The circuitry employs two RTD-PD devices in parallel. The oscillation frequencies range from 20-44 GHz with maximum attainable power about 1 mW at 34/37/44GHz.European Commission [645369

Broadband Bow-Tie Slot Antenna with Tuning Stub for Resonant Tunnelling Diode Oscillators with Novel Configuration for Substrate Effects Suppression

Radiation from antennas integrated with InP-based resonant tunnelling diode (RTD) oscillators is usually degraded because of the effects of the large dielectric constant substrate. The common solution has been to use hemispherical lenses to extract the signal from the backside of the substrate. In this paper we present a broadband bow-tie slot antenna with tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to air-side direction. The antenna was designed and fabricated using photolithography techniques to offer wide bandwidth (return loss S11 <-10dB) between 200-350 GHz on semi-insulating InP substrate with dielectric constant of ϵr = 12.56. Simulated and measured bandwidth almost extends the frequency range 230-325 GHz. Simulations shows air-side radiation pattern, an antenna gain of around 11 dB at 290 GHz and 98% radiation efficiency

IV Characteristics of a Stabilized Resonant Tunnelling Diodes

The presence of parasitic oscillations found in the negative differential region (NDR), which can distort the current-voltage (I-V) characteristics of the device is one of the main problems when designing resonant tunnelling diode (RTD) circuits. A new method for RTD stabilization is proposed based on work done previously on tunnel diodes and results show that there is a significant difference between the I-V characteristics of a tunnel diode and that of an RTD. This work shows promising potential for further increasing the RTD’s output power, DC-RF conversion efficiency and provides the basis for an accurate model of the NDR regio

Diced and grounded broadband bow-tie antenna with tuning stub for resonant tunnelling diode terahertz oscillators

Radiation from antennas integrated with indium phosphide (InP)-based resonant tunnelling diode (RTD) oscillators is mainly through the substrate because of the effects of the large dielectric constant. Therefore, hemispherical lenses are used to extract the signal from the backside of the substrate. In this study the authors present a broadband bow-tie slot antenna with a tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to the air-side direction. Antenna integration with RTD oscillators is described in this study as well. Two-port bow-tie slot antennas were designed and characterised and showed the suitability of integration with power combining RTD oscillator circuits which are based on mutual coupling. The antennas were fabricated using electron beam lithography on a semi-insulating InP substrate. Simulated and measured bandwidth almost extends the entire frequency range 230–325  GHz. Simulations shows air-side radiation pattern and antenna gain of around 11  dB at 280  GHz. Simulations also show that the antenna may be fed with a 50-Ω or 30-Ω feed line, i.e. suitable feed lines, without compromising its performance which may prove beneficial for optimum loading of RTD oscillators

Novel Tunnel Diode Oscillator Power Combining Circuit Topology Based on Synchronisation

Devices with negative differential resistance (NDR) regions in their current-voltage (I-V) characteristics such as tunnel diodes (TD) and resonant tunneling diodes (RTDs) have been used for realizing high frequency oscillators. In this paper, a new power combining technique is presented which combines output power through synchronisation of two coupled tunnel diode oscillators. The measured output power of the two synchronised tunnel diode oscillators realized in microstrip hybrid technology was -6.72 dBm at 716.2 MHz, while that of single tunnel diode oscillator was -9.09 dBm at 575.7 MHz. The circuit topology proposed in this paper can be utilized to realize high power and high frequency RTD terahertz sources

Compact J-band Oscillators with 1 mW RF Output Power and over 110 GHz Modulation Bandwidth

We report a compact resonant tunneling diode (RTD) oscillator with 1 mW output power at 260 GHz and a modulation bandwidth of over 110 GHz. The oscillator employs an RTD device size of 4 × 4 μm 2 resonating with an 88 μm long microstrip inductor. The total chip size is 470 × 530 μm 2. All fabrication was done using the low cost photolithography technique

AlGaN/GaN HEMT with Distributed Gate for Improved Thermal Performance

This paper reports a novel type of distributed gate (DG) HEMT fabricated using isolation by oxygen plasma. The technique results in planar devices with low gate leakage currents of only 1.3 μA/mm at -20 V gate voltage for devices with gate periphery of 1 mm. The DG-HEMT improves the thermal performance by reducing the current drop at higher drain voltages leading to higher output powers