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Biasng Network For RF switch

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monolothics

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Hi
I want to design a phase shifter using microstrip that worked at 2.4 GHz
and using MASWSS0136 as switch

what i want to ask is how to design a bias network for MASWSS0136 switch???

so far what i've been searching is to use the λ/4 bias tee or radial stub
but i guess the bias tee and radial stub is used to biasing LNA or HPA

can anyone help??
thanks
 

rf1008

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Naybe i can't understand your meaning of your application.

MASWSS0136 is a general RF SPDT device and doesn't need DC bias, the V1 and V2 are control signal to choose which RF path will be used.In this condition a bypass capacitor at V1 and V2 is enough,such as 10pF or 22pF for 2.4GHz application.
 

monolothics

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hi rf1008
appreciate the reply

yeah maybe i'm confusing about bias network so my question isn't quite clear
but can i use high impdance microstrip line instead of bypass capacitor?

thanks
 

biff44

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yeah, what he said! Add caps to ground at v1 and v2, but be careful if you need fast switching time--do not make them large value!
 

rf1008

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hi rf1008
appreciate the reply

yeah maybe i'm confusing about bias network so my question isn't quite clear
but can i use high impdance microstrip line instead of bypass capacitor?

thanks

High impedance utrip line is as choke and can't replace bypass capacotpr . Of course you may use both high impedance utrip line and bypass capacitor to construct LPF for better interference suppression, but you should consider your control signal at V1/V2 not be impressed as biff44 said.

High impedance utrip line and fan-shape structure are used at bias network in higher frequency.
 

monolothics

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hi,,
what if this switch : MASWSS0180,
does this switch need bypass capacitor on v1 and v2 too??

thanks
 

tony_lth

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the bypass cap always should be added, but depend on the situation, such as PCB layout, and EMC, etc, the cap values should be different.
 

monolothics

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hi tony_lth
thanks for the reply

but in the datasheet there's no explanation of using capacitor on the v1 and v2 port??
and how about on the RFin port, is it need capacitor too??

thanks
 

tony_lth

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The dc decoupling capacitors are determined by the applications and freq bands, no constant value for every situation.
If you add capacitor on RF path, what is your purpose? do you have basic knowledge of microwave technologies? It will shunt RF signal to GND>
 

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