Browsing by Subject "Ka-band"

Now showing 1 - 3 of 3

Open Access
GaN HEMT based MMIC design and fabrication for Ka-band applications
(2020-07) Akoğlu, Büşra Çankaya
Gallium Nitride (GaN) technology has recently dominated the high power applications in the mm-wave frequencies, and its commercial use is emerging with the upcoming 5G technology. High Electron Mobility Transistors (HEMTs) based on GaN show superior material properties and high power densities, which makes them promising candidates to utilize for Monolithic Microwave Integrated Circuits (MMICs) in high frequency applications. NANOTAM’s 0.15µm/0.2µm GaN HEMT on Silicon Carbide (SiC) microfabrication process is used to fabricate the transistors and passive components. Process steps are explained, as well as in-house epitaxial growth. Fabricated transistors are characterized for their direct current (DC), small-signal, and large-signal performances. T-gate structure of the transistors is optimized for the highest gain performance at 35GHz. A three-stage MMIC ampliﬁer is designed, fabricated in two process cycles, and measurements are performed on-wafer at room temperature. The best performing MMIC shows a small-signal gain higher than 23.1dB with an output power of 31.9dBm and a power-added eﬃciency (PAE) of 26.5% at 35GHz.
Open Access
High efficiency 35 GHz MMICs based on 0.2 μm AlGaN/GaN HEMT technology
(Cambridge University Press, 2022-06-16) Akoğlu, Büşra Çankaya; Sütbaş, Batuhan; Özbay, Ekmel
In this paper, two high efficiency monolithic microwave integrated circuits (MMICs) are demonstrated using NANOTAM's in-house Ka-band fabrication technology. AlGaN/GaN HEMTs with 0.2 μm gate lengths are characterized, and an output power density of 2.9 W/mm is achieved at 35 GHz. A three-stage driver amplifier MMIC is designed, which has a measured gain higher than 19.3 dB across the frequency band of 33–36 GHz. The driver amplifier exhibits 31.9 dB output power and 26.5% power-added efficiency (PAE) at 35 GHz using 20 V supply voltage with 30% duty cycle. Another two-stage MMIC is realized as a power amplifier with a total output gate periphery of 1.8 mm. The output power and PAE of the power amplifier are measured as 3.91 W and 26.3%, respectively, at 35 GHz using 20 V supply voltage with 30% duty cycle. The high efficiency MMICs presented in this paper exhibit the capabilities of NANOTAM's 0.2 μm AlGaN/GaN on SiC technology.
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.