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
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: A question of LNA Posted: Thu Mar 30, 2006 9:47 am
Joined: Thu Mar 30, 2006 9:20 am
Hello ,I'm a student and know a little ADS .I'm designing the
LNA.When I have mathed input and output impedance using the L and C,I can design the PCB .But the appliances
should't link directly to each other .there are shuold be the transmission line between them .How should I decide
the transmission line width and length .How do I measure The influence of the ransmission line .Should the input
and output impedanc be changed??[/url]
Post subject: Posted: Thu Mar 30, 2006 5:37
Joined: Mon Jun 27, 2005 2:02 pm
When designing a matching circuit you should take into consideration the transmission lines that
connect between the matching components. In general, these transmission lines should have an impedance of 50 ohm.
You can calculate the width of the line by using LINECalc (A tool of ADS), or just by using a formula (Depednding
on the type of transmission line you use - Co-Planar, µstrip etc). Series transmission lines (50 ohm) will add
delay (phase angle), you will see it on the smith chart. The impedances will be changed of course, but you can
tune the values of the components to compensate for that. Also take into consideration that the components have
tolerance. Finally see that the matching circuit provides the required matching all over the required BW.
What is your operating frequency and BW??