I have a RX chain whose cascaded noise figure increases, then decreases after a mixer (which is not possible?!) before increasing down the chain. The final cascaded noise figure reported is 1 dB lower than one calculated by spreadsheet. The help files mentioned that I check the cascaded gain, which I did, and it is correct. I also increased the no of noise points, with didn't help. Are there other factors that I should have taken care of? What is happening here?