Özet:

In this article, we demonstrate a low-cost 7.25-7.75 GHz two-stage low noise amplifier with sub-1-dB noise figure for satellite communication applications. The microstrip technology on Rogers RT5880 substrate with the dielectric constant of 2.2 and thickness of 0.508 mm were utilized to develop a low noise amplifier. The printed-circuit-board technology offers a variety of profits such as being low-cost, lighter-weight and re-configurability after the manufacturing process make this technology charming for satellite communication systems for both commercial and military applications. Since the monolithic microwave integrate circuit technology provide much smaller sized circuits and high electrical performance especially at the millimeter-wave frequencies, the printed microstrip technology can be a significant rival to integrated-circuit technology with its proven reliability, easier, cheaper and faster manufacturing process, compactible electrical performance in X-band applications. Moreover, the proposed amplifier was developed with utilizing California Eastern Laboratories’ CE3512K2 transistor on Rogers-RT5880 and surface mount devices were utilized in the matching networks to reduce the size. In addition, the source-generation and interstage matching topologies were implemented to simplify the matching complexity to enhance the noise and gain. The prototype was manufactured with utilizing LPKF prototyping machine. The developed LNA exhibits a measured gain of 23.5±0.5 dB with the noise figure of less than 0.9 dB and input/output return loss better than 11.5 dB in the operating frequency bandwidth. Furthermore, the developed amplifier has a measured carrier to interference of -59 dBc and P1dB of 13 dBm at the center frequency while consuming a total DC power of 50 mW.

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