> A typical RF CHOKE is lossy (deliberately) and hence one > would not normally > use a relatively high-Q PCB track to implement a choke.
Er, not necessarily. Having a lossy choke (series DC) is good in that it widens the bandwidth, but note that if you have a high power amplifier, drawing oodles of current, that series R is going to dissipate LOTS of power. Not really what you want either from an efficiency or thermal management standpoint. For "de-Qing" the feed from a hi-Q inductor, I've often seen a resistor applied in parallel to it. That way most of the DC current goes through the inductor, but as the Z of the inductor increases with frequency, the resistor adds a resistive component to the parallel pair of components. > 1/4 wavelength line is not what I would call a choke. Choke > to me is a > soggy inductor. A 1/4 wavelength line is more likely to be a > moderate to > High-Q resonator and has a different function to the old-stye > broadband, > flat response chokes. They're used a "bias feeds" at higher frequencies (microwave especially). Hi-Z at the desired frequency, low-Z at DC. > Brian G. and others wrote a spiral track generator for > Protel. Use that. OOooo!! Where's that?! Does it lock the tracks together so that they don't get independently pulled and the group can be drug together? I've not tried to make a "footprint" like this, I've just drawn the thing and had to redo it if I want to move it. Hopefully there's a better way. I don't live and breathe Protel. Sorry if the comments are nit picks, but just wanted to provide another POV. Thanks & regards, -- Mark Randol, RF Evaluation Engineer Motorola SPS, Inc. M/S EL536 2100 E. Elliot Road Tempe, AZ 85284 (480)413-8052 Voice (480)413-8690 FAX <mailto:[EMAIL PROTECTED]> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
