MICRF213 datasheet(13/16 Pages) MICREL

13 / 16 page

Micrel, Inc.

MICRF213

May 2007

M9999-052307-A

(408) 944-0800

PCB Considerations and Layout

Figure 11 through 16 show some of the printed circuit

layers for the QR211HE1 board. The MICRF213

shares the exact same board with different component

values. Use the Gerber files provided (downloadable

from Micrel Website: www.micrel.com) which have the

remaining layers needed to fabricate this board. When

copying or making one’s own boards, be sure and

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are no longer valid.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 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.

not

vias

with

ground

connections. Each ground connection = 1 via or more

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, only FR4 or better materials.

Phenolic material is conductive above 200MHz. The

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.

Figure 11. QR211/213HE1 Top Layer

Figure 12. QR211/213HE1 Bottom Layer, Mirror Image

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