An X-band Low Noise Amplifier in 0.25- $\mu \mathrm{m}$ GaAs pHEMT Process

Abstract

This paper presents a 2-stage X-band low-noise amplifier (LNA). The self-biased common-source amplifier is employed as the core unit of this LNA. A resistor is introduced to improve the stability of this LNA. The method employing a resistor connected to bypass capacitor is proposed in this paper to improve the small-signal gain flatness. The source degeneration inductor is employed to improve the bandwidth of the presented LNA. This proposed LNA is fabricated in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.25\text{-}\mu\mathrm{m}$</tex> GaAs pHEMT process. The measurement results show that the small signal gain is of 13.5 dB, the flatness is less than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 0.4\text{dB}$</tex> over the whole operating frequency band. The post-layout simulation results show that the output 1 dB compression point is greater than 8 dBm, the typical noise figure is 2.5dB. The power consumption of the circuit is 180mW while the supply voltage is 5V. The whole area of the presented LNA is 2.0mm*1.2mm.