Inductance lead effects - RF Cafe Forums
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Post subject: Inductance lead effects Posted: Fri Sep 09, 2005 3:59 am
Joined: Tue Mar 15, 2005 11:43 pm
I'm currently designing 3.5GHz power amplifier module, with the clip pin lead. I'm wondering whether the inductance of the lead (especially output lead) will significantly affect the performance?
and also due to the substrate thickness, the lead will be bent to connect to evaluation board (jig). So, there'll be gaps in between. I'm not sure whether it'll affect the performance especially at 3.5GHz range?
I've done some simulation by adding some inductance at the output. The gain is not significantly affected, but there's some effect at output return loss ( although not "high" ). Since so far, I only be able to do small signal simulation, I'm worried that it'll affect power performance at the end.
Could anybody kindly advise me how to do the "right and accurate" simulations to observe/ predict the effects on overall performance?
I need to prepare some anaylsis before send to fabrication.
Your advice is much appreciated.
Thanks and Regards,.
Post subject: Posted: Fri Sep 09, 2005 9:03 am
Joined: Mon Jun 27, 2005 2:02 pm
I didn't understand compleltly from your description what is a clip pin lead
Could you tell what is the package type?
If you mean that there is an air gap between one pin of yor active device to the substrate this will certainly cause a discontinuity in the impedance and will affect your return loss. If this occurs at the output it could be worse, because as you may know, the output is much more dominant in PA design.
I think that you can simulate an air-gap by measuring the dimensions of the air-gap and add a shape(s) of transmission line(s) with the same dimensions that has a dielectric coefficient of Er=1 (Dielectric coefficient of air).
Please provide the information above so I can help you more.
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