Post subject: CPWG Line width and spacings Posted:
Tue Jan 06, 2009 9:18 am
Aug 16, 2006 8:20 am
I am using a CPWG topology for one of my board design. I find that
line width of 40 mil with 18 mils spacing from adjoining ground
on a 20 mil Rogers 4350 substrate gives a 50 ohm impedance. Similarly
a 20 mil wide trace with spacing of 5 mils also yields 50 ohm for
same 20 mil thick substrate.
To take advantage of the low
loss offered by a 40 mil trace I went for this choice. While the
components in the RF portion (3 GHz to 7 GHz) of the design were
easily routed with this trace width, the components in Base Band
section (DC to 250 MHz) had inputs and output which run parallel
to each other. This makes using 40 mil wide trace with 20 mil ground
spacing difficult. however I can accommodate the 20 mil wide and
5 mil spacing easily.
Has anyone ever used two different CPWG
dimensions on the same PCB. Also would it be a good idea to do so.
The main IC creating problem is HMC626LP5 from Hittite. It is a
VGA with an Attenuator between two amplifiers. the input and output
of each amplifier are on same side separated by a single Ground
Post subject: Posted: Sat Jan 10,
2009 12:30 pm
Joined: Mon Jun 27,
2005 2:02 pm
There should be no problem to route the signal lines in
the configuration you mentioned as long as it gives 50-ohm impedance.
For the control signal you can use 5mil lines as they require no
Post subject: Posted: Mon Jan 12, 2009 2:17 am
Joined: Wed Aug 16, 2006 8:20 am
Thanks for your suggestions
Design Engineer- RF