Re: [avr-chat] Sample program for ATmeGA128RFA1

[Joerg Wunsch]

David VanHorn <address@hidden> wrote:

> These chips also spew harmonics if the output impedance is too far
> off.

The key to a good supression of the second harmonics is to
keep everything symmetric.  That way, most of the 2nd harmonics
that still leave the internal PA will compensate outside.

It's really recommendable though to add external lowpass filters.
The baluns recommended in the datasheet do already have them.  But
if you use a symmetric antenna, you better add two PI filters.

(ETSI harmonics supression is just reachable even without them, but
not much margin is left, so Tx power should be reduced a bit to gain
margin.  FCC harmonics supression requirements are a bit harder, and
always require a lowpass filter.)

-- 
cheers, Joerg               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/
Never trust an operating system you don't have sources for. ;-)