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MOSFET (Si/SiC) Forum Discussions

User21999
Level 1
First question asked First reply posted
Level 1
Hello support team,

i am planning to use Bgb707l7esd in my project for satellite receiver.

i have below query regarding this part number.

As per the layer stacking information given from your end, we have below query.

As layer stack up shows in application note (https://www.infineon.com/cms/en/product/rf-wireless-control/low-noise-amplifier-lna-ics/general-purp...) that it has top layer of rogers and bottom layer of FR4 for BGB707L7ESD,
I want to use FR4 as both layers. Is it possible or it will effect the performance?


Kindly request you to provide information as soon as possible.

Thanks
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1 Solution
Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Nidhi,

I discussed your concern with the author of the app note.
This is the conclusion:

Using FR4 for the top layer of the PCB instead of Rogers wouldn’t impact the performance of the LNA. You need to adjust the RF trace width(50-ohm microstrip line) according to the FR4 materials dielectric constant and the substrate height.

I hope this satisfies your doubt.

Let me know if you need anything else.
Best regards,

Pablo

View solution in original post

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Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Nidhi,

Thank you for posting on Infineon Forums.
I will check internally about the performance of Bgb707l7esd with FR4 top layer and I will get to you as soon as I have an answer.

Best regards,
Pablo
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Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Nidhi,

I discussed your concern with the author of the app note.
This is the conclusion:

Using FR4 for the top layer of the PCB instead of Rogers wouldn’t impact the performance of the LNA. You need to adjust the RF trace width(50-ohm microstrip line) according to the FR4 materials dielectric constant and the substrate height.

I hope this satisfies your doubt.

Let me know if you need anything else.
Best regards,

Pablo
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User21999
Level 1
First question asked First reply posted
Level 1
Hello Pablo,

Thank you so much for your prompt reply.

Can you please provide layer stack up for FR 4 material that will be help to calculate trace width and avoid iteration in design.

Thanks
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Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Nidhi,

As seen on the datasheet, there are three copper layers with two FR4 layers.
5183.attach

If I misunderstood your question, please let me know.

You can use any online tool like the following one to calculate the width.
https://www.everythingrf.com/rf-calculators/microstrip-width-calculator

Best regards,
Pablo
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User21999
Level 1
First question asked First reply posted
Level 1
Hello Support Team,


we have one problem in fabrication. we are only capable of making a PCB in FR4 2 layer or 4 layer and herewith i have attached layer stackup for the same, Is it possible to have the same performance with the attached layer stack up.

I have calculate the trace width for 50 ohm impedance :

FR4 2 layer: 2.9mm
FR4 4 layer: 0.31mm

Kindly guide and verify regarding that. As per my understanding i have taken copper and prepag thickness in consideration please guide if i am wrong.

waiting for your valuable support.

Thannks
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Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Nidhi,

Please understand that this is the Power Mosfet forum and not an RF forum.
Thus our knowledge of the subject is limited.
I recommend you post in an RF community that can guide you with calculations.

As far as your calculations are concerned, I see no problem.

Best regards,
Pablo
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User21999
Level 1
First question asked First reply posted
Level 1
Hello,

Can you please share link of RF forum.
we have search that but didn't get .


Thanks
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Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Nidhi,

By RF forum, I meant other communities on the internet, as Infineon does not have a dedicated RF sub-forum.
If you have any other Infineon product-specific questions, you can always post on our forum.
You can also post RF questions on our forum. However, have in mind that we do not have dedicated RF engineers on this forum.
Therefore you would be relying on other forum users who may have RF experience.

Best regards,
Pablo
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