TRANSISTOR FOR EFFICIENT 900 MHz, 100mW PA ? - RF Cafe Forums
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Post subject: TRANSISTOR FOR EFFICIENT 900 MHz, 100mW PA ?
Unread postPosted: Thu Sep 02, 2004 6:59 am
Any suggestions on a nice transistor for a PA at 900MHz with good efficiency? Spec:-
Pout: 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 Bipolar
Size: Small parts preferred
Cost: Not critical
Post subject: 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
use a constant current source bias.
Post subject: 100 mW amp
Unread postPosted: Sat Sep 11, 2004 9:03 am
Don't know if this is better, the efficiency may be a bit off,
but talk about simple...
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