MICRF219A_15 datasheet(19/25 Pages) MICREL

19 / 25 page

Micrel, Inc.

MICRF219A

August 12, 2015

Revision 3.0

RadioTech@micrel.com or (408) 944-0800

PCB Considerations and Layout

The MICRF219A 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 then

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

better

materials

are

recommended. The RF path should be as straight as

possible

avoid

loops

and

unnecessary

turns.

Separate ground and VDD lines from other digital or

switching power circuits (such microcontroller, etc).

Known sources of noise should be laid out as far as

possible from the RF circuits. Avoid unnecessary wide

traces which would add more distribution capacitance

(between top trace to bottom GND plane) and alter the

RF parameters.

MICRF219A 数据表(PDF) 19 Page - Micrel Semiconductor

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