nRF9160 schematic design questions

[Nishantt]

Hello,

We are using nRF9160 for asset tracking product. We used nRF52832 as an BLE+MCU. I have some queries regarding the schematic design of nRF9160.

1. Is it mandatory to use LNA and Antenna tuner circuitry for GPS antenna? or I can just go with T or Pi matching circuitry? 

2. What is the purpose of COEX pins? We are using the BLE of nRF52832 and using nRF9160 for GPS and NB-IoT connectivity. Is it mandatory to use or I can let them unconnected? 
    We are sending GPS data to nRF52832 after every 30 mins and we required minimum current consumption for continues tracking. 

3. In datasheet it is written in VDD_GPIO recommendation : 

    VDD_GPIO should be applied after VDD has been supplied
    VDD_GPIO should be removed before removing VDD

    I am not sure how to design the circuit with above requirements.

4.  Please guide me to make RESET pin circuit as weel because I am bit confuse after seeing nRF9160 DK RESET circuit.

[ketiljo]

1. Using a LNA is highly recommended: https://infocenter.nordicsemi.com/topic/nwp_033/WP/nwp_033/nwp_033_gps.html

An antenna tuner is normally not needed but the antenna needs a pi or T match. 

2. https://infocenter.nordicsemi.com/topic/nwp_037/WP/nwp_037/coex_if.html

3. VDD_GPIO can be applied and removed together with VDD. 

4. https://infocenter.nordicsemi.com/topic/nwp_037/WP/nwp_037/nreset.html

[Nishantt]

Hello,

Thank you for your answers.

I have still some doubts in questions 1 & 4. 

1. Why in nRF9160 DK schematic it placed MHF connector before the LNA circuit? Please find below image from DK.
    Also please note that we are using BGS01SF011398 GPS patch antenna.
            

4. About the RESET circuit. It works on 2.2V and nrf52832 GPIO works on 3.3V. So I have to add one BJT (P/N : BC847CT-7-F ) for level shifting purposes or I can directly connect both (with the resistor in series as per recommendation)?

[ketiljo]

1. This is to be able to use an external, active antenna. It it's not needed, you can replace all this with a single 39 pF cap:

 

4. Reset is normally high so you can pull it down with any transistor but not directly connected to 2.2 V. 

[Nishantt]

Thank you for your support. I will raise one private ticket once our schematic design will be done.