Low-Noise GaAs HEMT for Digital Satellite Radio in C and S Bands

It offers a typical associated gain of 13.0dB at a frequency of 4GHz and, respectively, 18.0dB at 2.4GHz. Simultaneously the minimum noise figure is 0.35dB at both 4GHz and 2.4GHz – a value which is not only at the top level of the industry but also 0.1dB lower than with Mitsubishi’s 12GHz model MGF4953A.

With this excellent performance the new GaAs HEMT, which is integrated into an industry standard 4-pin full-mold package, is predestined for use in the first stage of low-noise amplifiers for satellite signals requiring excellent low-noise characteristics in order to improve sensitivity.

Satellite digital audio radio service (SDARS) has been present in North America since 2001 and has been widely adopted. In contrast to analogue radio services SDARS does not require tuning in order to adapt to regional broadcasting. Due to this convenience factor, SDARS is attractive for car information services such as traffic information and entertainment programs. With similar broadcast data services dubbed DAB (digital audio broadcasting) expected to start in other regions of the world, the satellite digital radio market is projected to grow globally in the near future.

All these systems require a special low-noise amplifier in order to amplify low-level satellite signals. Having passed this first amplification stage the S band signals (2 - 4GHz) are mixed down to an IF band (intermediate frequency) of about 0.8 to 1.5GHz before they are forwarded to the signal processing circuit.