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In this paper, we present a highly robust GaN-based X-band low-noise amplifier (LNA) showing promising small-signal and noise performance as well as good linearity. The LNA is fabricated using in-house 0.15 μm AlGaN/GaN on a SiC HEMT process. Owing to the optimum choice of HEMT topologies and simultaneous matching technique, LNA achieves a noise figure better than 2 dB, output power at 1 dB gain compression higher than 19 dB, input and output reflection coefficients better than À9 and À11 dB, respectively. The small-signal gain of LNA is more than 19 dB for the whole band, and NF has a minimum of 1.74 dB at 10.2 GHz. LNA obtains an OIP3 up to 34.2 dBm and survives input power as high as 42 dBm. Survivability is investigated in terms of gain compression and forward gate current. Reverse recovery time (RRT), a crucial parameter for radar front-ends, is explored with respect to the RC time constant and trap phenomenon. The analysis shows that the significant contribution in RRT is due to traps while the RC time constant is in the nanoseconds range. Moreover, this study also addresses the requirement and choice of a DC gate feed resistor for the subsequent stages in a multi-stage design. The size of the designed LNA chip is 3 mm  1.2 mm only.

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This paper reports design, fabrication and measurements of a wideband amplifier for UHF applications. A technology based on Gallium Nitride (GaN) transistor is used to design a class-AB amplifier with compact dimensions which can be employed as a driver stage for many UHF applications with wideband requirements. Wideband impedance transformers at input and output of the amplifier are implemented to achieve the wideband features including higher gain and efficiency. The designed amplifier is fabricated and then characterized to verify the design parameters and it has been observed that the simulated results are in agreement with the measured ones. Maximum RF output of SW (37dBm) is demonstrated over frequencies ranging from IS0-S00 MHz with gain flatness of 2.SdB. Flatness of ±O.SdB is shown within 220-S00MHz. The measured powergain is found to be above 17dB for the entire band.

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