The datasheets of the HMC575 and HMC573 frequency doublers only give residual phase noise at 100 kHz offset. Can you perhaps provide a graph over a wider offset frequency range?

Admittedly this should be easier to answer than it is. I have not been able to find the original characterization data. I was able to determine the number in the HMC575 datasheet was based on 4GHz input frequency. From there you can mathematically determine some reasonable numbers using these formulas.

100kHz PN = datasheet number + 10*log(fout/4GHz)

For different phase offset you can use a 10*log(offset frequency) curve.

What particular frequencies and offset are you interested in?

My requirement is to multiply 3.6 GHz to 14.4 GHz. I am mostly interested in the phase noise at the higher offsets, i.e. 1 MHz and 10 MHz. If I look at the phase noise graphs for the HMC561, HMC368 and HMC814, also frequency doublers, it seems as if the drop in PN is slightly less than 10 dB /decade, but I could make an estimate based on those, if you think they are representative?

In contrast, the phase noise of the X4 multiplier HMC370 already bottoms out at 100kHz and doesn't drop much after that. I am worried that the HMC575 and HMC573 might do the same.

My requirement is to multiply 3.6 GHz to 14.4 GHz. I am mostly interested in the phase noise at the higher offsets, i.e. 1 MHz and 10 MHz. If I look at the phase noise graphs for the HMC561, HMC368 and HMC814, also frequency doublers, it seems as if the drop in PN is slightly less than 10 dB /decade, but I could make an estimate based on those, if you think they are representative?

In contrast, the phase noise of the X4 multiplier HMC370 already bottoms out at 100kHz and doesn't drop much after that. I am worried that the HMC575 and HMC573 might do the same.

I have some boards on order, that won't be in until later this week. I will make some absolute phase noise measurements (<12G output) for you (not residual, as I don't have that equipment on hand). I will check a couple spot frequencies. We can go from there.

Absolute Phase Noise Plots for HMC573 and HMC575. These include the phase noise from the signal generator. Signal generator was set to 4.5GHz. Both parts phase noise at 9GHz. If the input signal source is limitting the phase noise, the 9GHz output should be 20*log(M), where M=2 for the multiplication factor (6dB). This looks to be the case. So these plots let you know the HMC57x phase noise is better than these plots show. Does this help?