match network <CC1120>

WH HUANG

Hello, we just follow the reference design <420 - 470MHZ>, now we like to insert a SAW filter <output Z=50ohm> , so we need to design a match network between SAW and the BALUN ? so what the impedance on BALUN input?

directly to use C18 / L3 is ok, no need to design a match network ???

sorry about my poor english, and thanks for your input.

over 10 years ago

0 TER over 10 years ago

TI__Guru**** 317180 points

If you only want a filter in the Rx path, use the topology shown in: www.ti.com/.../tidr229.pdf (component values needs to be taken from the 433 MHz ref design)

0 WH HUANG over 10 years ago in reply to TER

Expert 1530 points

thanks, but the 433MHZ ref design has no SAW filter yet. and we dont know the impedance on the Balun circuit . so we have no idea to make a match network.
insert serial LC between SAW out and Balun INPUT is wrong way.

0 TER over 10 years ago in reply to WH HUANG

TI__Guru**** 317180 points

As the schematic I included in the last post shows the point you point the arrow to in your first post is a 50 ohm point.

0 WH HUANG over 10 years ago in reply to TER

Expert 1530 points

sorry , can you direatly show us the L3 / C 18 values for ISM 433MHZ application ?

we have read the follow thread, so we like you can tell the match network compnonents value.

e2e.ti.com/.../155715

0 WH HUANG over 10 years ago in reply to WH HUANG

Expert 1530 points

Sorry ,i am back now. just check the datasheet, it shows the optimum source impedance is <100+j60/50+j30>

so we like to use the optimum source impedance:

the balun input (optimum source impedance should be 55nH//42ohm) ? right? or we still need to use the VNA to do matching network?

Thanks.

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match network <CC1120>