Post subject: CPWG Line width and spacings Posted:
Tue Jan 06, 2009 9:18 am
Joined: Wed 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 pin.
Design Engineer- RF
Post subject: Posted: Sat Jan 10, 2009 12:30
Joined: Mon Jun 27, 2005 2:02 pm
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 specific impedance.
Post subject: Posted: Mon Jan 12,
2009 2:17 am
Joined: Wed Aug 16, 2006 8:20
Thanks for your