Designer’s Guide Community

michael_li New Member Offline Posts: 4	inductance of the exposed pad bondwire Dec 04^th, 2006, 6:20am In my 2000MHz PA Driver circuit design,I use bondwire inductor emitter negative feedback. To get higher gain,I bond the emitter to the Exposed Pad of the QFN48 package,so the bondwire inductance is estimated 1nH.Is that right,or it should be 500pH?
Back to top	IP Logged

ACWWong

Community Fellow

Offline

Posts: 539
Oxford, UK

Re: inductance of the exposed pad bondwire
Reply #1 - Dec 4^th, 2006, 6:50am

It depends on how long it is (and other dimensions) and what the adjacent bondwires are etc. etc.
So 1nH is ok as an approximation for the self inductance of a 1mm length of bondwire. 0.5nH is ok for something like 0.6mm. Depending on adjacent bondwires, mutal inductance can act to change the effective value you use.
You can find references to bondwire inductance formulae in something like Tom Lee's "Design of CMOS Radio Frequency Integrated Circuits"

Back to top

IP Logged

loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: inductance of the exposed pad bondwire Reply #2 - Dec 4^th, 2006, 9:21am In addition to the textbook references, electromagnetic model tools (Sonnett, ASITIC, and others) will allow development of an inductance and magentic coupling model. Manufacturers of the QFN package (popular in RF circles due to low L) also develop more complete package models for their customers. Jerry
Back to top	Jerry Twomey www.effectiveelectrons.com Read My Electronic Design Column Here Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical IP Logged

ACWWong Community Fellow Offline Posts: 539 Oxford, UK	Re: inductance of the exposed pad bondwire Reply #3 - Dec 4^th, 2006, 9:33am yes best port of call is are your packaging people... as loose says, they normally can give you some model data: I just googled and found this: http://www.ose.com.tw/ic/en/packaging_service.asp but you could also try amkor or unisem...
Back to top	IP Logged

loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: inductance of the exposed pad bondwire Reply #4 - Dec 4^th, 2006, 1:26pm Amkor is pretty good at developing package models for their products. Good results seen from them! :)
Back to top	Jerry Twomey www.effectiveelectrons.com Read My Electronic Design Column Here Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical IP Logged

michael_li New Member Offline Posts: 4	Re: inductance of the exposed pad bondwire Reply #5 - Dec 5^th, 2006, 1:59am You are so kind. Thanks all of you. So I will check it with the package factory.
Back to top	IP Logged