Windfreak Technologies
Exodus Advanced Communications Best in Class RF Amplifier SSPAs
 

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!
Anatech Electronics

PIN diode bias question... - 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

bparker
Post subject: PIN diode bias question... Posted: Wed Nov 23, 2005 6:29 am

Lieutenant

Joined: Fri Aug 27, 2004 11:25 am
Posts: 4
Location: Cape Town, R.S.A.
Hi All,


A fundamental question regarding PIN diodes and their biasing – How does one calculate the minimum DC voltage required to ensure that a PIN diode remains OFF in the presence of RF?

In a specific system implementation, where a PIN diode RF switch is used to cold switch 500 W RF pulsed signal, a shunt diode configuration is used. In this existing system a reverse bias of 50V is used to switch the diodes OFF, but it was shown experimentally that the reverse voltage could be dropped as low as 25V before the RF began to bias the diodes ON.

First of all I understand that 500W RF power corresponds to a RF voltage swing of 450Vp-p, if 50 ohm is assumed. This on top of a -50V bias (for switching the diodes OFF) means that the signal is swinging between -275V and +175V, which one would think would bias the diodes ON during the positive cycle. The minority carrier lifetime of the PIN diode however is related to the fact that this does not happen and the diode remains OFF for the complete duration.

The question then remains, what is the relationship between minority carrier lifetime, RF power, frequency and other PIN diode specifications and this minimum reverse bias voltage to ensure that the diodes remain OFF.

Am I missing something obvious? I've searched through various application notes and other literature, which somehow always seem to ignore this requirement.


_________________
B.K.P.


Top

Peter Raynald
Post subject: Posted: Wed Nov 23, 2005 11:44 pm

Captain


Joined: Tue Sep 07, 2004 3:09 pm
Posts: 11
Hello BKP,

This is an interesting question.

As I know when used as attenuators, pin diode long minority carrier lifetime drives the hability of the diode to provide good intermodulation caracteristic.

In a two tone intermodulation test the enveloppe being non-constant, I see this also as the hability to resist bias change by the enveloppe modulation.

I wonder if the equations for linearity of a pin diode attenuator in high attenuation condition would be useful... like the one from MACOM or Alpha. You would be using a criterion for extremely low distortion meaning the diode absorbs no power.



Posted  11/12/2012
KR Electronics (RF Filters) - RF Cafe
Werbel Microwave - RF Cafe
LOTUS Communications Systems Modular RF Component Building Blocks - RF Cafe
 

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

These Are Available for Free