Triad RF Systems
Berkeley Nucleonics Academy RF Boot Camp - RF Cafe
 

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

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!
Innovative Power Products Combiners / Dividers

Noise figure increase - 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

shireesha
 Post subject: Noise figure increase
Posted: Wed Dec 09, 2009 6:40 am 
 
Captain

Joined: Wed Jun 04, 2008 3:23 am
Posts: 11
Hello,
I am trying to design a 30 dB Low noise amplifier at 9.5 GHz using the FHX13X super low noise HEMT from fujitsu as the first stage. I am able to meet all the specs but I have encountered a weird phenomenon. During the noise figure measurement for a certain percentage of modules the noise figure starts low (around the designed spec of 1.2 dB) and goes on to slowly increase with time to 2.5 dB. For every measurement cycle (of the noise figure analayzer) it seems to increase 0.02 dB. What are the possible reasons for this?

Thanks.


 
   
 
maxwell
 Post subject: Re: Noise figure increase
Posted: Fri Dec 18, 2009 12:13 pm 
 
Captain
 

Joined: Mon Sep 01, 2003 6:59 pm
Posts: 13
Location: Boston
Are these packaged LNA, or open substrate? The increasing NF over time suggests either a charge accumulating (possibly bias capacitance), or a temperature realted issue. Both could be caused by poor solder joints. Have you already ruled out these two possibilities?






Posted  11/12/2012
high frequency PCB of PCBONLINE
withwave microwave devices - RF Cafe
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