The Qorvo QM14501 LNA in nRF9160 reference schematic seems to be consuming several mA of current, which is quite a lot for a GPS LNA. There are other LNA chips in the market, which use less current, but their IIP3 / 1dB compression point is lower. Are there any specific demands to compression characteristics of the GPS LNA, as it sits next to the cellular TX antenna etc.? Has the higher compression point LNA (QM14501) selected to the ref. design, because lower-compression point (and lower current consumption) GPS LNAs would saturate or produce cellular TX harmonics due to the high RF field generated by the cellular TX antenna of nRF9160?
Are these nRF9160 datasheet GPS sensitivity figures including or excluding the use of QM14501 LNA ?
- Acquisition sensitivity: -144 dBm for cold start, -147 dBm for hot start
- Acquisition time: 30 seconds for cold start, 5 seconds for hot start
- Tracking sensitivity: -149 dBm (open sky received power ≥ -130 dBm)
If the LNA is not used at all, how much less sensitivity there is for the GPS? What are those figures then?
