Browsing by Subject "Coplanar waveguide"

Now showing 1 - 7 of 7

Open Access
Compact and wideband CPW wilkinson power dividers for GaN MMIC applications
(IEEE, 2018) Sutbas, Batuhan; Özbay, Ekmel; Atalar, Abdullah
This paper presents two types of modified CPW Wilkinson power dividers at X-band using GaN MMIC technology on a SiC substrate. Lumped element equivalents of the transmission line arms are used and they are capacitively loaded to achieve a reduced circuit size of lambda/14timeslambda/8. A symmetrical series RLC circuit in the isolation network is used to compensate for the bandwidth degradation after circuit miniaturization maintaining a fractional bandwidth of 29 % for input/output return losses and isolation better than 20 dB with an extra insertion loss less than 0.35 dB.
Open Access
Improved Wilkinson power divider structures for millimeter-wave applications
(2019-01) Sütbaş, Batuhan
Communication systems, radars, electronic warfare and space applications desire integrated circuits with higher operating frequencies. Working at the millimeter-wave region increases data rates, provides a more efficient use of the spectrum and enables smaller products. Power dividers are used as building blocks for such applications to split and combine RF signals. Wilkinson power divider is one of the most commonly used topology, providing high return loss and isolation with low insertion loss. However, it occupies valuable chip area, has a limited bandwidth, requires accurate modeling and precise fabrication. In addition, the layout becomes complicated for three or more outputs and cannot be realized on a planar circuit. This work presents three techniques to address the drawbacks of the original Wilkinson divider. The first structure achieves a compact size without bandwidth degradation and provides additional physical isolation at the output. The second divider improves the bandwidth of operation and increases tolerance to sheet resistance variance, enabling robustness and higher yields. The third technique simplifies the layout of three-way dividers and allows a planar fabrication technology. The proposed structures are analyzed using even-odd mode analysis and design equations are derived. Three high performance dividers with 30 GHz center frequency are designed employing the developed methods. The circuits are realized using GaN based coplanar waveguide and microstrip monolithic microwave integrated circuit technology. Experimental results demonstrate good agreement with theory and simulations, proving that the presented improvements could be useful in future millimeter-wave RF applications.
Open Access
Structural field plate length optimization for high power applications
(IEEE, 2014) Toprak, Ahmet; Kurt, Gökhan; Şen, Özlem A.; Özbay, Ekmel
In this work, we report GaN high-electron-mobility-transistors (HEMTs) on SiC with field plates of various dimensions for optimum performance. 0.6 μm gate length, 3 μm drain source space AlGaN/GaN HEMTs with field-plate lengths of 0.2, 0.3, 0.5 and 0.7 μm have been fabricated. Great enhancement in radio frequency (RF) output power density was achieved with acceptable compromise in small signal gain. When biased at 35 V, at 3 dB gain compression, a continuous wave output power density of 5.2 W/mm, power-added efficiency (PAE) of 33% and small gain of 11.4 dB were obtained at 8 GHz using device with 0.5 μm field plate length and 800 μm gate width without using via hole technology.
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
X Band GaN Based MMIC power amplifier with 36.5dBm P1-dB for space applications
(IEEE, 2018) Gürdal, Armağan; Yilmaz, Burak Alptug; Cengiz, Ömer; Şen, Özlem; Özbay, Ekmel
An X-Band Monolithic Microwave Integrated Circuit (MMIC) High Power Amplifier (HPA) with coplanar waveguide (CPW) based on AIGaN/GaN on SiC technology is presented in this paper. Coplanar waveguide technology (CPW) is chosen for the simplicity and reduced cost of fabrication since CPW process has no via. High Electron Mobility Transistors (HEMTs) are matched for the 8 GHz-8.4GHz frequency band for maximum output power. The Amplifier has a small signal gain over 10 dB, output power of 36.5dBm at 1 dB gain compression point (P1dB) and 40% power added efficiency (P AE) at (PldB) in the desired frequency band (8 GHz-8.4 GHz) with Vds = 30V.
Open Access
X band GaN based MMIC power amplifier with 36.5dBm P1-dB for space applications
(IEEE, 2018) Gürdal, Armağan; Yılmaz, Burak Alptuğ; Cengiz, Ömer; Sen, Özlem; Özbay, Ekmel
An X-Band Monolithic Microwave Integrated Circuit (MMIC) High Power Amplifier (HPA) with coplanar waveguide (CPW) based on AlGaN/GaN on SiC technology is presented in this paper. Coplanar waveguide technology (CPW) is chosen for the simplicity and reduced cost of fabrication since CPW process has no via. High Electron Mobility Transistors (HEMTs) are matched for the 8 GHz-8.4GHz frequency band for maximum output power. The Amplifier has a small signal gain over 10 dB, output power of 36.5dBm at 1 dB gain compression point (P1dB) and 40% power added efficiency (PAE) at (PldB) in the desired frequency band (8 GHz-8.4 GHz) with Vds = 30V.
Open Access
X-band high power GaN SPDT MMIC RF switches
(IEEE, 2019) Osmanoğlu, Sinan; Özbay, Ekmel
This paper describes the design results and measured performance of three different high power, low loss and high isolation GaN high electron mobility transistor (HEMT) based single-pole double-throw (SPDT) RF switches. Three different topologies were employed to design the proposed switches. The SPDT MMIC switches were developed with coplanar waveguide (CPW) GaN-HEMT technology to operate in X-Band. The measured performance showed that the switches have typical insertion loss of better than 2 dB, higher than 30 dB isolation with better than 10 dB return losses.