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RF switch selection

udi-eng

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I am designing a Lora RF board based on STM32WL ic.

the reference design uses a RF switch BGS12SN6. I would like to replace it in my design to SKY13453-385LF.

1) the new IC requirement states " Must be DC blocked" for the RF ports. I believe the reference design includes this, but would like to verify.

2) There are some differences between the original and replacement components: I don't know which parameters are critical to review, and which are less important: insertion loss, Isolation, Return loss, 2nd harmonics ,3rd harmonics ...
 

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BigBoss

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C2,C12,C13 Provide DC Isolation, no worry.
They are pretty similar but the specifications of BGS12SN6 are slightly better in term of Insertion Loss and Isolation but they are very close.
The Cases are different but you can modify the PCB thought.
I believe you can use the equivalent without any problem.
 

biff44

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C2,C12,C13 Provide DC Isolation, no worry.
They are pretty similar but the specifications of BGS12SN6 are slightly better in term of Insertion Loss and Isolation but they are very close.
The Cases are different but you can modify the PCB thought.
I believe you can use the equivalent without any problem.
i agree, all four rf ports are already dc blocked

you do realize that skyworks part is a two throw switch, right?
you have to make sure the control voltages you use match up with the skyworks switch requirements.
 

vfone

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BGS12SN6 and SKY13453-385LF are SP2T (Single Pole Double Throw) switches when BGS13S4N9 is a SP3T (3 ways) switch.
So you cannot just replace an SP3T switch with a single SP2T switch.
You can replace an SP3T switch with two SP2T switches, but the switching logic become more complicated (and the insertion loss higher).
According to datasheets, to avoid DC issues, is better to use DC blocking capacitors on any of these switches.
 

udi-eng

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BGS12SN6 and SKY13453-385LF are SP2T (Single Pole Double Throw) switches when BGS13S4N9 is a SP3T (3 ways) switch.
So you cannot just replace an SP3T switch with a single SP2T switch.
You can replace an SP3T switch with two SP2T switches, but the switching logic become more complicated (and the insertion loss higher).
According to datasheets, to avoid DC issues, is better to use DC blocking capacitors on any of these switches.
Thanks for your comment, ST also provides a schematics with SP2T, that is BGS12SN6 in a layout application note for this part, so I took this as a reference. the reason I used the SP3T schematics is because it shows the whole rf part
 

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