Design of a 10GHz LNA for Amateur Radio Operation Using AWR Software
6 www.cadence.com/go/awr
The layout of the designed LNA is shown in Figure 10. The RF input is on the right and output is on the left edge. Layouts were
done for both NE3512S02 and NE3503M04 pHEMTs. Figure 10 also shows the NE3512S02 pattern (and its mirror resist for
etching).
Figure 10: LNA layout (left) and mirror (right)
Construction Process
Construction of the LNA began with resist patterning and etching of the circuit board. The board was then etched in a
homemade bubble etcher and finished with a thin tin plate. Via holes were defined with a 35 mil drill. Figure 11 shows the
undrilled, etched board placed in the undrilled housing.
With the home-brew board process, it was necessary to solder wires in the through holes at each via location. An interior view
of the completed LNA is shown in Figure 11. The input is on the right and output on the left. The 3.3V regulator can be seen on
the left wall. The DC circuitry can clearly be seen along the top of the board and the RF amplifier stages on the lower portion.
Four small rectangles of Eccosorb can also be seen attached to DC bias feed lines. This was done for practical reasons as
insurance against parasitic feedback paths, although likely not needed. As stated earlier, moding suppression was needed in
this housing because 10GHz will propagate through a cavity this large. Eccosorb patches were placed on the right and lower
side walls as well as on the inside of the cover. Stability behavior was excellent.
Figure 11: Etched, undrilled board placed in undrilled housing, interior view of completed LNA, and completed 10GHz LNA
The completed LNA can be seen in Figure 11. The measured gain is just over +18dB and the associated noise figure (NF) is near
2dB. While this met the performance targets for use in the 10GHz station, the predicted levels were a bit better. The differ-
ences can be attributed to poor line-width control and excess via inductance in the home-fabricated circuit board.
