X-band MMIC amplifier with pulse-doped GaAs MESFET's

The design and test of an X-band monolithic four-stage low-noise amplifier (LNA) with 0.5 mu m-gate pulse-doped GaAs MESFETs for application in a direct broadcast satellite (DBS) converter is presented. The key feature of the research is a detailed demonstration of the advantages of using series feedback with experiments and simulations. This LNA shows an excellent input VSWR match under 1.4 as well as a noise figure of 1.67 dB and a gain of 24 dB at 12 GHz. The noise figure, the gain and VSWRs exhibit very little bias current dependence due to the exceptional features of the pulse-doped structure FETs and the optimized circuit design. Insensitivity to bias current implies performance stability in the face of process fluctuations. Thus, the yield of chips with noise figures of less than 2.0 dB is as high as 62.5%, and the variations of gain and VSWR are highly uniform as well.<
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