GaAs based MMIC LNA for X-band Applications

This paper presents a 2-stage X-band( 8-12GHz) low-noise amplifier (LNA), which is fabricated in a 0.25-mu m GaAs pHEMT process. The source degeneration inductor is adopted in this paper to improve the bandwidth of the LNA, which helps to increase the real part of the input impedance. The gain reduction mechanism while using the degeneration inductor is also discussed at the same time. The micro-line, which has inductance characteristics, takes place of the degeneration inductor in this paper. Therefore, a method to select this micro-line is proposed to achieve a better performance of the LNA in this paper. In addition, lossy matching networks are designed to increase the bandwidth. The measurement results of the fabricated LNA show that the typical small signal gain is 20 dB with the flatness less than +/- 0.4dB over the operating frequency band. The post-layout simulation results show that the output 1 dB compression point is greater than 13 dBm, the typical noise figure is of 1.5dB. The power consumption is 215mW while the supply voltage is 5V. The whole area of the presented LNA is 2.2 mm x 1.2mm.