Electronics World Cover,TOC,and list of posted Popular Electronics articles QST Radio & TV News Radio-Craft Radio-Electronics Short Wave Craft Wireless World About RF Cafe RF Cafe Homepage RF Cafe in Morse Code Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs Twitter LinkedIn Crosswords Engineering Humor Kirt's Cogitations Engineering Event Calendar RF Engineering Quizzes AN/MPN-14 Radar 5CCG Notable Quotes App Notes Calculators Education Magazines Software,T-Shirts,Coffee Mugs Articles - submitted by RF Cafe visitors Simulators Technical Writings RF Cafe Archives Test Notes Wireless System Designer RF Stencils for Visio Shapes for Word Search RF Cafe Sitemap Advertising Facebook RF Cafe Forums Thank you for visiting RF Cafe!

How Can I Match 100K Om to 12K Om - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

Amateur Radio | Antennas | Circuits & Components | Systems | Test & Measurement


cpeter
Post subject: How can I match 100K om to 12K om
Unread postPosted: Wed Mar 09, 2005 11:32 pm
Offline
Lieutenant

Joined: Wed Mar 09, 2005 11:20 pm
Posts: 2
I am doing a design:

AD9854 -> differential & quadrature signal -> 80MHz filter & match network? -> AD8346

And:
output impedance of AD9854: 100k om
input impedance of AD8346: 12k om

how can I design the filter & match circuit?

Thanks.
Peter


Top
Profile

Guest
Post subject: Impedance matching?
Unread postPosted: Sun Mar 13, 2005 10:18 pm

Peter,
Your question leaves out some important information - such as the frequency range involved.

The impedances you cite are only accurate at very low frequencies. There is significant reactance present at any reasonable RF frequency. (There's both bond wire inductance and bonding pad capacitance to ground).

The implication is that you probably don't want to match 100k to 12k, since you really won't have it anyway! Digital-to-Analog converters are often driven into the summing junction of an operational amplifier - which is a "virtual ground". From the classical RF viewpoint, that's weird - but the DAC output is often essentially a current, which must be converted to a voltage.

Check out Analog Devices' application notes on the AD9854 - I'm sure that they don't show the kind of impedance-matching network you're asking for.

Good Luck!


Top


cpeter
Post subject: Thanks.
Unread postPosted: Wed Mar 16, 2005 1:47 am
Offline
Lieutenant

Joined: Wed Mar 09, 2005 11:20 pm
Posts: 2
You answer is very helpful, thanks a lot!
:D







Posted  11/12/2012

RF Cafe Software

   Wireless System Designer - RF Cafe
Wireless System Designer

RF & EE Symbols Word
RF Stencils for Visio
Calculator Workbook
RF Workbench
Smith Chartâ„¢ for Visio
Smith Chartâ„¢ for Excel

About RF Cafe

Kirt Blattenberger - RF Cafe WebmasterCopyright
1996 - 2022
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...

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

Try Using SEARCH
to Find What You Need. 
There are 1,000s of Pages Indexed on RF Cafe !

height-line