A monolithic four-stage low-noise amplifier (LNA) was successfully demonstrated for direct broadcast satellite (DBS) down-converters using 0.3 µm gate pulse-doped GaAs MESFET's This paper presents the design and test results of the LNA. The key feature of the research is a detailed demonstration of the difference between a noise figure of the four-stage LNA and an optimal noise figure of an employed FET with simulation and experiments. This LNA shows VSWR's of below 1.5: 1 as well as a noise figure of 1.1 dB and a gain of 28 dB at 12 GHz. To the best of our knowledge, it is the lowest noise figure reported so far in 12 GHz-band MMIC amplifiers. In the power characteristics, a 1 dB compression point (P1dB) of 10 dBm and a third order intercept point (IP3) of 19 dBm were shown.