Browsing by Subject "Coplanar waveguides"

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Open Access
Design of multi-octave band GaN-HEMT power amplifier
(IEEE, 2012) Eren, Gulesin; Şen, Özlem A.; Bölükbaş, Basar; Kurt, Gökhan; Arıcan, Orkun; Cengiz, Ömer; Ünal, Sıla T.K.; Durmuş, Yıldırım; Özbay, Ekmel
This paper describes design, fabrication and measurement of 6 GHz - 18 GHz monolithic microwave integrated circuit (MMIC) amplifier. The amplifier is realized as coplanar waveguide (CPW) circuit using 0.3 μm-gate Gallium-Nitride (GaN) HEMT technology. The amplifier has a small signal gain of 7 ± 0.75 dB. The output power at 3dB compression is better than 24 dBm with 16%-19% drain efficiency for the whole 6 GHz-18 GHz frequency band under continuous wave (CW) power. © 2012 IEEE.
Open Access
On-chip characterization of THz Schottky diodes using non-contact probes
(IEEE Computer Society, 2016) Khan, T. M.; Ghobadi, A.; Celik, O.; Caglayan, C.; Bıyıklı, Necmi; Okyay, Ali Kemal; Topalli, K.; Sertel, K.
We present non-contact characterization of GaAs Schottky contacts in the 140-220 GHz band. The non-contact probing technique utilizes planar on-chip antennas that are monolithically integrated with the coplanar waveguide environment housing the Schottky diode under test. The diode contact is fabricated through a 6 mask lithographic process with a 5 μm deep-trench under the contact to minimize parasitics and extend operation into the THz band. A quasi-optical link between the VNA ports and on-chip probe antennas enables efficient signal coupling into the test device. The non-contact probe station is calibrated using on-chip quick-offset-short method and the effectiveness of this approach is demonstrated for integrated diodes for under various bias conditions.
Open Access
Study of the power performance of gaN based HEMTs with varying field plate lengths
(North Atlantic University Union, 2015) Kurt G.; Toprak, A.; Sen O.A.; Özbay, Ekmel
In this paper, we report the optimum power performance of GaN based high-electron-mobility-transistors (HEMTs) on SiC substrate with the field plates of various dimensions. The AlGaN/GaN HEMTs are fabricated with 0.6 µm gate length, 3 µm drain-source space. And also, the field plate structures with the lengths of 0.2, 0.3, 0.5, and 0.7 µm have been fabricated on these HEMTs. Great enhancement in radio frequency (RF) output power density was achieved with acceptable compromise in small signal gain. A HEMT of 0.5 µm field plate length and 800 µm gate width is biased under 35 V, at 3 dB gain compression, The results showed that we obtained a continuous wave output power of 36.2 dBm (5.2 W/mm), power-added efficiency (PAE) of 33% and a small signal gain of 11.4 dB from this device. We also could achieve a continuous wave output power of 37.2 dBm (5.2 W/mm), poweradded efficiency (PAE) of 33.7% and a small gain of 10.7 dB from another HEMT with 0.5 µm field plate length and 1000 µm gate width. These results were obtained at 8 GHz without using a via hole technology. The results seem very stunning in this respect. © 2015, North Atlantic University Union. All rights reserved.
Open Access
Three dimensional microfabricated broadband patch and multifunction reconfigurable antennae for 60 GHz applications
(IEEE, 2015-04) Hünerli H. V.; Mopidevi, H.; Cağatay, E.; Imbert, M.; Romeu, J.; Jofre, L.; Çetiner, B. A.; Bıyıklı, Necmi
In this paper we present two antenna designs capable of covering the IEEE 802.11ad (WiGig) frequency band (57-66 GHz and 59-66 GHz respectively). The work below reports the design, microfabrication and characterization of a broadband patch antenna along with the design and microfabrication of multifunction reconfigurable antenna (MRA) in its static form excluding active switching. The first design is a patch antenna where the energy is coupled with a conductor-backed (CB) coplanar waveguide (CPW)-fed loop slot, resulting in a broad bandwidth. The feed circuitry along with the loop is formed on a quartz substrate (at 60 GHz), on top of which an SU-8-based three-dimensional (3D) structure with air cavities is microfabricated. The patch metallization is deposited on top of this structure. The second design is a CB CPW-fed loop slot coupled patch antenna with a parasitic layer on top. The feed circuitry along with the loop is formed on a quartz substrate. On top, the patch metallization is patterned on another quartz substrate. The parasitic pixels are deposited on top of these two quartz layers on top of an SU-8 based 3D structure with air cavities. © 2015 EurAAP.