MICRF229 datasheet(18/23 Pages) MICREL

18 / 23 page

Micrel, Inc.

MICRF229

April 15, 2015

Revision 1.0

PCB Considerations and Layout

The MICRF229 evaluation board is a good starting point

for prototyping of most applications. The Gerber files are

downloadable from the Micrel website and contain the

remaining layers needed to fabricate this board. When

copying or making one’s own boards, make the traces as

short as possible. Long traces alter the matching network

and the values suggested are no longer valid. Suggested

matching values may vary due to PCB variations. A PCB

trace 100 mils (2.5mm) long has about 1.1nH inductance.

Optimization should always be done with range tests.

Make sure the individual ground connection has a

dedicated via rather than sharing a few of ground points

by a single via. Sharing ground via will increase the

ground path inductance. Ground plane should be solid

and with no sudden interruptions. Avoid using ground

plane on top layer next to the matching elements. It

normally

adds

additional

stray

capacitance

which

changes the matching. Do not use Phenolic materials as

they are conductive above 200MHz. Typically, FR4 or

better materials are recommended. The RF path should

straight

possible

avoid

loops

and

unnecessary turns. Separate ground and VDD lines from

other digital or switching power circuits (such as

microcontrollers, etc.). Known sources of noise should be

laid out as far as possible from the RF circuits. Avoid

unnecessary

wide

traces

which

would

add

distribution capacitance (between top trace to bottom

GND plane) and alter the RF parameters.

MICRF229 Datasheet(PDF) 18 Page - Micrel Semiconductor

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