Triad RF Systems
LadyBug Technologies LB5944A RF Power Sensor - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024
    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:

Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes App Notes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Homepage Thank you for visiting RF Cafe!
everythingRF RF & Microwave Parts Database (h2) - RF Cafe

Cascade P1dB - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. If the folks at phpBB would release a version with integrated sign-in from the major social media platforms, I would resurrect the RF Cafe Forums, but until then it is probably not worth the effort. Regardless, there are still lots of great posts in the archive that ware worth looking at.

Below are the old forum threads, including responses to the original posts.

-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews
-- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

Post subject: Cascade P1dB Posted: Mon Oct 01, 2007 7:26 am


Joined: Tue Sep 04, 2007 7:54 am
Posts: 13
Location: Dallas
Is there any general rule of thumb when slecting amplifiers in a chain so that maximum P1dB can be realized from the chain. I know that last stage of the chain should be the highest P1dB amplifier. Curious to know if there any techniques to arrange the amplifiers tio get maximum P1dB.


Post subject: Posted: Thu Oct 04, 2007 4:31 am


Joined: Tue Mar 15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi there,

You are right, for multi-stages power amplifier the largest P1dB should be at the last stage. Or in other words, your last stage should be the largest device with largest current handling capability.

But keep in mind that P1dB is related to the input power too.
So the key is you have to drive enough power (enough gain) to get the correct level of P1dB that you expected.
Besides, to drive high P1dB, you need good matching, especially output matching and interstage matching. Without good interstage-matching, it is difficult to get high P1dB.

Input matching might not be too critical in this case.
Having said that, your preceding stages are as critical as your last stage to determine high P1dB.

I hope it helps.

Jean (Wavestream Corp)


Post subject: Posted: Thu Oct 04, 2007 5:58 pm

Site Admin

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany

Just to add to the points that Jean mentioned:

You should take care that the stage before the last stage will not get into saturation. In other words, you should drive the amplifier so that only the last stage will be in P1dB. If the first and middle stages will be driven into saturation, you will loose gain and will not reach into the full output power that the amplifier is capable to.

Posted  11/12/2012
high frequency PCB of PCBONLINE
EMC Directory
Axiom Test Equipment - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free