Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: TRANSISTOR FOR EFFICIENT 900 MHz, 100mW PA ?
Unread postPosted: Thu Sep 02, 2004
Any suggestions on a nice transistor for a PA at 900MHz with good efficiency? Spec:-
50 to 100 mW
Supply rail: 3 Volts
Frequency: 900 MHz
Class: Probably C or
harmonic terminated etc (need best efficiency)
Efficiency: Target of better than 60%
Transistor type: Fet or
Size: Small parts preferred
Cost: Not critical
Any suggestions on a nice transistor for a PA at 900MHz with
Unread postPosted: Thu Sep 09, 2004 2:08 pm
I've had some great luck with an Infineon BFP450
at those levels, efficiencies and frequencies. Hint
a constant current source bias.
Post subject: 100 mW amp
Sat Sep 11, 2004 9:03 am
Don't know if this is better, the efficiency may be a bit off,
but talk about
Guest - IFX
Unread postPosted: Sat Sep 11, 2004 11:42 pm
Use only Infineon BFP450 for your application. It is very stable and easy to tune to 900MHz.
It is a
SiGe Device with Ft of 25GHz
http://www.infineon.com/cmc_upload/docu ... bfp450.pdf
http://www.infineon.com/cmc_upload/migr ... pli026.pdf
http://www.infineon.com/cgi/ecrm.dll/ec ... ?oid=13759
If you need more gain add BFP420 / BFP 520 /
BFP 620 as a driver to your +20dBm PA.
With Best Regards,
Guest - IFX
Unread postPosted: Mon Sep 13, 2004 9:12 am
Thanks to you all,
Strange (or maybe not) but I ended up prototyping a BFP450 amp last week. Performance is reasonable without trying
very hard (circa 45 to 50% collector eff') but quite a bit harder to get any more efficiency than that. I tried a
harmonic termination of 2F and then 3F but this did not gain me much for quite a bit more complexity!
Thanks again anyway