•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe™

Sitemap

How to choose the device for PAs and LNAs - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


johnjohn
Post subject: How to choose the device for PAs and LNAs Posted: Thu Nov 17, 2005 4:46 pm

Lieutenant

Joined: Thu Nov 17, 2005 4:29 pm
Posts: 1
I am working with a SiGe BiCMOS process that has different size bipolars.
For emitter width, we have three choices: 0.4um, 0.6um and 0.9um.

I have read some paper saying that for a PA, there is a relationship
between the maximum output power and the emitter area. Does anybody
know what is the exact relationship? Is that coming from the parasitic
considerations or others?

If we somehow determined the total emitter area of the PA. Which
emitter width to use? Some paper say that the narrower emitter
gives better NFmin and higher Ft. How can that be explained?
Even if that is true, it would apply to LNAs. Can PAs benefit from this?
(given that we don't care about noise of PAs)


Thanks


Top

Jeanalmira
Post subject: Posted: Thu Nov 24, 2005 4:23 am

General


Joined: Tue Mar 15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi :

I am sorry for my comments that are probably not directly related to SiGe BiCMOS devices, as I havent experienced using this device before

Just general comments on device for PA and LNA design. Usually for LNA design, we choose device with higher cut-off frequency as the noise figure will be lower, for example HEMT devices.

As for PA design, we choose device based on the power requirement, that related to device impedance, gate width, etc. For example, in most cases, MESFET is preferable for PA design, while HEMT is preferable for LNA design.

Any further advice is appreciated...

Warm regards,
Jean (EUDA)



Posted  11/12/2012
Custom Search
More than 10,000 searchable pages indexed.

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website