AWR Application Notes

Design of a 10GHz LNA for Amateur Radio Operation

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Design of a 10GHz LNA for Amateur Radio Operation Using AWR Software 2 www.cadence.com/go/awr LNA Specifications The LNA was designed to operate from +12V with at least 18dB of gain, less than 2dB noise figure, and unconditional stability. Linear analysis, design tradeoffs, and tuning were performed with Cadence AWR ® Microwave Office ® circuit design software, which contributed significantly to the success of this project. The design steps are detailed in the following section. Since the final radio was to be built entirely at home without the benefit of commercial grade fabrication and assembly tools, some important choices needed to be made at the outset. Among these were: f Semiconductors must be packaged - CEL (Renesas/NEC) NE3512S02 or NE3503M04 were identified as good packaged pseudomorphic high electron mobility transistor (pHEMT) candidates for the two LNA stages. ɢ The pHEMT S-parameter and noise data were provided on the CEL website. ɢ This data included package parasitics and source grounding inductance over a range of bias conditions. ɢ A negative gate bias supply was required for operation of these depletion-mode field-effect transistors (FETs). f Rogers R04003C laminate for RF board - Rogers R04003C laminate is a good RF substrate with controlled dielectric properties. ɢ The dielectric constant was 3.38 ± 0.05. ɢ Sheets of this material were available in six different dielectric thicknesses. ɢ For this LNA, 20 mil material was selected. Resist patterning, etching, and vias are discussed later in this article. f An available standard package such as Hammond 1590LLB or 1590LBFL - The Hammond 1590LLB cast aluminum package was selected for this LNA. ɢ It was readily available and low in cost. ɢ The interior cavity was 1.834" x 1.834", which was large enough to support propagation down to just below 6.5GHz. ɢ Potential moding needed to be addressed in the construction with an RF damping material such as Eccosorb. f Amphenol 132147-48 2-hole SMA connectors - The connectors provided an RF interface compatible with a 20mil laminate and 80 mil housing thickness. ɢ The external dielectric sleeve could be trimmed to 80 mils (to match the package wall thickness). ɢ The external center contact could be trimmed to overlap with the circuit board by 25mils for microstrip launch.

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