Windfreak Technologies
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!
everythingRF RF & Microwave Parts Database (h2) - RF Cafe

Gate bias - 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

SDO
 Post subject: Gate bias
Posted: Fri Oct 22, 2010 5:59 am 
 
Captain
 

Joined: Tue Aug 26, 2008 5:18 am
Posts: 22
Location: UK
Hi,
Can any please explain to me how do we select the value of gate bias resistor in combination with inductor in the design of RF power amplifier. Inductor is frequency dependent but why do we use varios values of resistor apart from stability.
Thanks.
SDO


 
   
 
IR
 Post subject: Re: Gate bias
Posted: Mon Oct 25, 2010 2:00 pm 
 
Site Admin
 

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

Don't you mean a voltage divider?
if you mean a single bias resistor, can you show an example of such circuit?

_________________
Best regards,

- IR


 
   
 
SDO
 Post subject: Re: Gate bias
Posted: Thu Oct 28, 2010 2:48 am 
 
Captain
 

Joined: Tue Aug 26, 2008 5:18 am
Posts: 22
Location: UK
Hi,
Thanks for your reply. I am attaching JPeg of Schematic showing 27R resistor (R39). Please explain how do we select this select resistor. This PA has been designed for 60MHz.
I cannot attach/insert Image, anyhow this resistor is from gate to a series inductor and after that are decoupling caps on the gate bias. SO it is like DC--->decoupling caps--->inductor--->resistor--->gate. It is definitely not a voltage divider but used to present low impedance at low frequencies.


 
   
 
IR
 Post subject: Re: Gate bias
Posted: Thu Oct 28, 2010 4:33 am 
 
Site Admin
 

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
I guess that this is a recommendation by the transistor manufacturer.
Have you tried to simulate the circuit with and without the resistor?

This resistor is most probably used for stability and it works to stabilize the amplifier by reducing the gain in low frequencies (Where the gain is extremely high). The resistor works for DC to very low frequencies in which the reactance of the inductor has almost no influence.

_________________
Best regards,

- IR




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