Which Noise analysis for RF design?

I have to simulate the noise performances (with Spectre) of an active bandpass filter working up to 1.5 GHz. It's 50ohm input/output matched and what I do not understand is which noise analysis I must use. First, I used Noise analysis in Cadence and during the design I noticed clear noise improvement by choosing the right configuration, minimizing the use of resistors on the signal path and so on. I achieved this way a small noise figure of ~3-4 dB (for NF). The second possibility is to check the Noise option while doing an SP analysis but in opposite to the first case, I achieved high noise of about 30 dB and no decreasing possibility. I used input/output ports. How could I obtain the right noise figure? Many thanks.