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 Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Bittele Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol RF Superstore San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
Exodus Advanced Communications Best in Class RF Amplifier SSPAs - RF Cafe

RF amplifier Maximum ratings and complex waveforms - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 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. 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.

NOTICE: The original RF Cafe Forum is available again for reading, and the new RF Cafe Blog is an active board.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

kalisteuma

Post subject: RF amplifier Maximum ratings and complex waveforms Posted: Tue Oct 07, 2008 10:45 pm

Lieutenant

Joined: Tue Oct 07, 2008 10:19 pm

Posts: 1

Hi there,

I have a question on how to correctly rate the maximum peak power of a RF device, given its maximum drain (collector) voltage and maximum current and/or power dissipation. My question rises as more complex and demanding waveforms are being used in RF power amplifiers nowadays: higher peak-to-average ratios (PAR). More specifically I am looking for a guide on how to derive voltages and currents being developed at the devices terminals (not at the 50-Ohm impedance nodes) under a known set of conditions: Average power, PAR, VDD. Is it possible for someone to point me in the right direction on how to find this information?

Thank you

Kalisteuma

Top

FSomma

Post subject: Posted: Thu Oct 09, 2008 3:35 pm

Hello kalisteuma

It is very complex answer.. I don´t know if I can completely answer it..

When I design a power amplifier the first thing you have to analyze even before choosing any transistor is your input signal. It is not always that easy to know the PAR of the complex modulated signals, the best way is by measuring the CCDF curve of your signal (you can also simulate it). With the CCDF curve, you will have a record of the maximum peak power of the signal.

Then you select a transistor knowing the average power that you need and the peak power that your signal demands (of course that if your requirements allow it, you can chopp the output signal by reducing its PAR, selecting a smaller transistor). Let me clarify this with an example:

-If you have a signal with a PAR of 10dB and you need 10W of average power you will have to choose a 100W amplifier. In this case, the max peak power at the output will be 100W

-If you have a signal with a PAR of 10dB and you need 10W of average power and you choose a 50W amplifier. In this case, the max peak power at the output will be 50W and you will be chopping the signal to a PAR of 7dB.

-If you have a signal with a PAR of 5dB and you need 10W of average power and you choose a 100W amplifier. In this case, the max peak power at the output will be 31.6W and you will be using the amplifier with a lot of back off.

With the above information I was trying to explain how to rate the max output peak power of an amplifier.

Now if you want to know the peak voltage at the very output of the transistor you will need to know the impedance of that point. You can have that by measuring or asking to the manufacturer the loadpull data of the transistor.

Posted  11/12/2012

Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe
RF Cascade Workbook 2018 by RF Cafe
everythingRF RF & Microwave Parts Database - RF Cafe
Windfreak Technologies Frequency Synthesizers - RF Cafe
Anatech Electronics (RF Filters) - RF Cafe

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

These Are Available for Free

 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

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:

AirplanesAndRockets.com