GPS Antenna Circuit

RE: GPS Antenna Circuit

Yusuke — Fri, 09 Aug 2019 06:38:51 GMT

Yes, I did. Now, I'm doing impedance matching.

RE: GPS Antenna Circuit

a3p — Sat, 03 Aug 2019 16:26:03 GMT

this link is dead. could you point me to the current ref design. i can't seem to find it in the docs :/

RE: GPS Antenna Circuit

Hardik — Tue, 23 Jul 2019 08:44:49 GMT

Hi Yusuke,

We can use Band pass filter or RF Switch.

Are you done with your schematic part of GPS?

RE: GPS Antenna Circuit

Yusuke — Wed, 05 Jun 2019 15:13:06 GMT

Hi, Andreas. I'm designing a circuit related to gps antenna in nRF9160.

you said this.

>note that as there is no filter internally this might be needed externally

If you add a RF switch between GPS antenna and LNA(BGA715N7), it should work fine with BGA715N7, right? In my understanding, you need to select LNA equipped with filter only when you don't attach RF switch. Is this correct?

RE: GPS Antenna Circuit

Andreas — Mon, 27 May 2019 12:09:39 GMT

Hi,

This looks fine, but note that as there is no filter internally this might be needed externally.

Best regards,

Andreas

RE: GPS Antenna Circuit

Andreas — Mon, 27 May 2019 12:08:54 GMT

Hi,

Unfortunately we do not have much experience with different parts yet. Skyworks has a nice lineup though, both sole amplifiers and front-end modules (with filter).

Depending on the design, and the isolation between the antennas, it might also be needed to add a mechanism for disconnecting the GPS antenna during LTE transmission, e.g. the switch circuitry in some of the DK designs. We have not managed to characterize the general need for this yet. In any case, from a performance point of view, it should be in your best interest to place the two antennas as far apart as possible, which should increase the isolation.

Best regards,

Andreas

RE: GPS Antenna Circuit

GJSea — Sun, 26 May 2019 20:20:28 GMT

The Infineon BGA715N7 is what I'm going be basing our design on, it is readily available and has much higher 20dB gain, and uses less than half the current.

RE: GPS Antenna Circuit

Balamurugan — Fri, 24 May 2019 16:53:37 GMT

Thanks for pointing to new GPS circuit and explanation.

we do not find "QM14501"" in digikey or mouser to buy.

Could you recommend alternative component.

RE: GPS Antenna Circuit

Balamurugan — Fri, 24 May 2019 16:52:49 GMT

Thanks.

RE: GPS Antenna Circuit

Andreas — Fri, 24 May 2019 14:14:19 GMT

Hi,

This could possibly be used. As mentioned you should make sure you are able to replicate the recommended mounting in your end product, and that it supports the bands you plan on using.

I notice that it has two matching configurations, one that supports 700-800 MHz, and one that supports 820-960 MHz. If you plan on supporting both in your product you then need to implement an antenna tuning circuit, two RF switches that can switch to different antenna matching circuits depending on the band/frequency operating at.

Best regards,

Andreas

RE: GPS Antenna Circuit

Andreas — Fri, 24 May 2019 14:08:22 GMT

Hi,

Correct, the GPS circuitry in the current version of the DK is too complex and not performing very well. See the PS reference design for outlines of the general design. In general:

Green: LNA with LNA specific passives. We recommend an LNA that has the filter on the input.
Blue: Test connector - optional
Red: PCB antenna + antenna matching

You can also use an external antenna, depending on your product requirements. If using an active antenna, you would need a bias tee on your PCB.

You should choose a PCB antenna which has a recommended mounting that aligns well with your intended mounting. E.g. if it is recommended to be placed in the corner of a ground plane, it will not be optimal if you place it along a straight edge of the ground plane. You also need to ensure that it supports the frequency in which the bands you plan to use are placed.

Best regards,

Andreas

RE: GPS Antenna Circuit

Balamurugan — Fri, 24 May 2019 13:45:33 GMT

could we use https://www.mouser.in/datasheet/2/611/johanson_07052018_0830AT54A2200-1500417.pdf for Cellular-RF ?