Olle Axelsson

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In this paper, two Low Noise Amplifiers designed in Gallium Nitride HEMT MMIC technology are presented. The focus of the designs is to achieve good linearity at low power consumption and acceptable noise figure. The first design achieves an OIP<sub>3</sub>/P<sub>DC</sub> of 12 using traditional LNA design techniques. In a second design, the OIP<sub>3</sub>(More)
A bilayer SiN<sub>x</sub> passivation scheme has been developed using low pressure chemical vapor deposition (LPCVD), which effectively suppresses the dispersive effects in AlGaN/GaN high-electron-mobility transistors (HEMTs) for microwave power operation. The bilayer LPCVD passivation is compared with in-situ SiN<sub>x</sub> passivations by metal-organic(More)
This study investigates degradation of gallium nitride (GaN) high-electron mobility transistor (HEMT) noise performance after both dc and RF stress with forward gate current. The results are used to facilitate optimization of the robustness of GaN low-noise amplifiers (LNAs). It is shown that forward biasing the gate of a GaN HEMT results in permanent(More)
This study investigates recovery time of the gain of AlGaN/GaN HEMT based low noise amplifiers (LNA) after an input overdrive pulse. Three LNAs, fabricated in two commercial MMIC processes and a Chalmers in-house process, are evaluated. The Chalmers process has an unintentionally doped buffer instead of the intentional Fe doping of the buffer which is(More)
In this paper a highly linear amplifier using an in-house gallium nitride (GaN) high electron mobility transistor (HEMT) technology is presented. A 3 dB bandwidth of 2.7&#x2013;3.6 GHz with a maximum gain of 18 dB was measured. The output third-order intercept point (OIP3) was measured to 39 dBm with a maximum power consumption of 2.1 W. With a reduction of(More)
The growth, fabrication, and performance of Al<sub>0.5</sub>Ga<sub>0.5</sub> N/AlN/GaN high-electron-mobility transistors (HEMTs) with a total barrier thickness of 7 nm are reported. An optimized surface passivation and an ohmic recess etch yield HEMTs exhibiting 0.72 S/mm peak extrinsic dc transconductance at a current density of 0.47 A/mm. Devices with a(More)
A Low-Pressure-Chemical-Vapor-Deposition (LPCVD) bilayer SiN<sub>x</sub> passivation scheme has been investigated and developed, which effectively suppress the current collapse in AlGaN/GaN HEMTs. Low current slump is very helpful for microwave power amplifier application. Compared to in-situ SiN<sub>x</sub> passivations by(More)
High-frequency and low-frequency noise (LFN) performance of GaN high electron-mobility transistors (HEMTs), passivated with SiNx deposited by either in situ or low-pressure-chemical-vapor-deposition (LPCVD), are compared. From 8-26 GHz, the LPCVD sample has a lower minimum noise figure (1 dB at 8 GHz) because of lower power spectral density of noise sources(More)
This paper investigates the impact of different iron (Fe) buffer doping profiles on trapping effects in microwave AlGaN/gallium nitride (GaN) high electron mobility transistors (HEMTs). We characterize not only the current collapse due to trapping in the buffer, but also the recovery process, which is important in the analysis of suitable linearization(More)
In this paper, the noise temperature of an electronic tuner is determined and its significance for the suitability of such tuners in noise parameter measurement systems discussed. The noise temperature of the tuner was found to be higher than the ambient room temperature in the laboratory and vary significantly between tuner states. For impedance states(More)