MICRF218_11 MICREL [Micrel Semiconductor], MICRF218_11 Datasheet - Page 19

• Manufacturer Part Number: MICRF218_11
• Description: 3.3V, 315/433MHz Wide-IF Bandwidth ASK Receiver
• Manufacturer: MICREL [Micrel Semiconductor]

November 2011
PCB Considerations and Layout
Figures 14 to 17 show top, bottom and silkscreen
layers of printed circuit board for the QR218HE1
board.
downloadable from Micrel Website: www.micrel.com,
to fabricate this board. Keep traces as short as
possible. Long traces will alter the matching network,
and the values suggested will not be valid. Suggested
Matching Values may vary due to PCB variations. A
PCB trace 100 mills (2.5mm) long has about 1.1nH
inductance. Optimization should always be done with
exhaustive range tests. Make individual ground
connections to the ground plane with a via for each
ground connection. Do not share vias with ground
connections. Each ground connection = 1 via or more
Gerber
files
are
provided
Figure15. QR218HE1 Bottom Layer, Mirror Image.
Figure 14. QR218HE1 Top Layer.
and
are
19
vias. Ground plane must be solid and possibly without
interruptions. Avoid ground plane on top next to the
matching elements. It normally adds additional stray
capacitance which changes the matching. Do not use
phenolic material. Use only FR4 or better materials.
Phenolic material is conductive above 200MHz. RF
path should be as straight as possible avoiding loops
and unnecessary turns. Separate ground and Vdd
lines from other circuits (microcontroller, etc). Known
sources of noise should be laid out as far as possible
from the RF circuits. Avoid thick traces, the higher the
frequency, the thinner the trace should be in order to
minimize losses in the RF path.
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