Ublox MAX - M8 GPS Module, is a LNA and SAW filter necessary when using passive antennas?

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I intend to use the Ublox MAX - M8  GPS Module.

However it suggest that fro passive antenna’ that an external LNA and SAW filter is used.

Does anyone have any thoughts on this, is there a GPS module that you would recommend?
asked Feb 13 by joel

1 Answer

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For best performance with any receiver you want to minimize noise figure and remove interference - thus placing LNA/SAW near the antenna or using active antenna with SAW in it would give you best performance (same as u-blox describes in the datasheet).  Depending on what you need with respect to sensitivity you can go without active antenna or LNA.  If your design doesn't have sources of jamming (transmitters) then SAW may not be needed.  With active antenna you typically have NF of 1 dB, same is for LNA near passive antenna.  With MAX-M8 noise figure of 3.5 dB you would lose 2.5 dB + losses between antenna and MAX-M8 in sensitivity values - say about 2 dB.  If this is OK for your application then you do not need LNA or active antenna.
answered Feb 13 by grumpy Senior Principal Expert