Is the circuit around GNSS of nRF9160 DK 0.8.5 reliable?

[Yusuke]

According to the blog below, hardware design of nRF9160-SICA has been fixed on May 31st.
https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/nrf9160-development-status

I'm designing GNSS-relate circuit which is connected to nRF9160 and need a reference for it.

Is it Ok to design a circuit referring to nRF9160 DK 0.8.5?
https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF9160-DK/Download#infotabs
Isn't there any design update in the GNSS related circuit of the next version of nRF9160 DK?

If so, I will imitate the nRF9160 DK 0.8.5; nRF9160(GNSS port) - LNA - RF switch - GNSS antenna
I'll use BGA524N6E6327XTSA1 for LNA. This doesn't have a filter.
https://www.mouser.jp/datasheet/2/196/Infineon-BGA524N6-DS-v03_00-en-1225539.pdf
Also, I'll use SKY13522-644LF for RF switch
http://www.skyworksinc.com/uploads/documents/SKY13522_644LF_202858E.pdf

I know that software update will be required to let GNSS function perform fully.

Any advice and suggestions are welcome.

Thanks.

[Kaja]

Hi Yusuke,

so the DK 0.8.5 has an working GNSS circuitry, and you can design after that. 

Your design chooses sounds fine, I'm happy to review the rest of the schematic when its ready. 

Best regards,
Kaja

[Yusuke]

Hi, Kaja

This is GNSS circuit of my design.
To reduce power consumption, I want to enable LNA(IC8) only when GPS function is needed. GPS_RF_AMP_EN line controls the enable of IC8.

Also, RF switch(SKY13522-644LF) V1 port is connected to MAGPIO0 port of nRF9160 through RFSW_V1. MAGPIO0 can be controlled by AT command.
Due to the maxium input voltage of SW2, RFSW_V1 voltage is devided and input to the V1 port

I chose ACAG0301-1575-T for GNSS antenna.
https://abracon.com/datasheets/ACAG0301-1575-T.pdf

Can you review this? Thanks a lot!

[Kaja]

Hi Yusuke, 

so the circuitry in general looks fine, L3 should be the value stated in the LNA datasheet, 8.2 nH. The pi-network out of the GPS pin is not need seen from the chips side, the output impedance of the GPS pin is 50 Ohm. 

Best regards,
Kaja

[Yusuke]

Thank you!

This is the final design. If you see wrong thing, let me know.

[Yusuke]

Hi, Kaja

I have one more question. How about using saw filter like below? I think you don't need RF switch in this case.

nRF9160(GPS port) --- LNA --- SAW filter --- antenna

[chirag.aumraj]

Hi Kaja,

Is it necessary to use RF switch between LNA and Antenna? I want to use an onchip GPS antenna on my custom board.

if yes, then why we need to use it?

Thank you,

Chirag