I'd like to use the HMC5805ALS6 from 0.5GHz to 18GHz. The datasheet gives a typical NF of 4.5dB from DC to 5GHz. But looking at the Noise Figure vs Frequency curve in the datasheet shows that the NF increases very quickly at low frequencies, up to 10dB or more.
How can I have a reliable estimation of the NF at 0.5GHz ? Will it be more close to 5dB, 10dB, 15dB? Or more ?
Since I've seen some similar NF vs Frequency curves in other HMC amplifiers I was wondering what could be the physical/technological reason of such behavior ?
Thanks in advance for your help !