MICRF112_13 datasheet(14/21 Pages) MICREL

14 / 21 page

Micrel, Inc.

MICRF112

February 2013

M9999-020713

Output Matching Network

Part of the function of the output network is to attenuate

the second and third harmonics. When matching to a

transmit frequency, be sure not only to optimize for

maximum output power but to attenuate unwanted

harmonics.

Layout Issues

PCB layout is extremely important to achieve optimum

performance and consistent manufacturing results. Be

careful with the orientation of the components to ensure

that they do not couple or decouple the RF signal. PCB

trace length should be short, to minimize parasitic

inductance (1in ~ 20nH). For example, depending on

inductance values, a 0.5in trace can change the

inductance by as much as 10%. To reduce parasitic

inductance, the use of wide traces and a ground plane

under signal traces is recommended. Use vias with low

value inductance for components requiring a connection

to ground.

Antenna Layout

The antenna trace layout affects directivity. No ground

plane should be under the antenna trace. For consistent

performance, do not place components inside the loop of

the antenna. Gerbers for the Evaluation Board PCB, with

a suggested layout are available on the Micrel web site

at: www.micrel.com.

MICRF112 데이터시트(PDF) 14 Page - Micrel Semiconductor