Hello,
Let me try to clarify.
First you should not confuse BlueNRG-LP matching/filtering and antenna matching.
BlueNRG-LP has a nearly 50 Ohms RF output but it requires few extra components to ensure best RF matching and also filtering to reject spurious emission (Harmonic2, Harmonic3 etc) and be compliant with regional certification (CE, FCC etc)
Then depending on antenna selected and also on layout or product mechanical parts, it is needed to add few components for antenna matching.
This will ensure antenna will radiate at proper frequency.
As you noted there are two different solutions depending STEVAL-IDB011V1 or V2.
With V1 version
- C30, C5, L1 and C6 are here to ensure proper BlueNRG-LP matching.
- U2 is a Low Pass Filter to ensure harmonic rejection.
- C42, L3 and C43 are dedciated to ensure proper antenna matching. Considering there is not a specific antenna here (SMA connector), no antenna matching is done (just 0 Ohm)
With V2 version, the idea was to replace the Low Pass Filter components was a full discrete solution.
- C30, C5, C42, L1, C6, L3 and C43 are acting for BlueNRG-LP matching and filtering
- Again, considering there is not a specific antenna here (SMA connector), no antenna matching is implemented or even shown here.
So hope that clarified the difference between both eval kits.
As said before, it is always recommended to have 2 or 3 components for matching an antenna.
Despite we will be perfectly 50 Ohms after BlueNRG-LP matching/filtering and despite antenna is also supposed to be perfectly 50 Ohms, in reality this never happens and having no matching will not allow to get an antenna radiating at proper frequency.
Antenna matching must be done with a VNA (Vector Network Analyser) by checking S11 parameter.
Regards
Laurent
