ADMV4530 Phase Noise at the EVB

Hi kosta_tr

If you can provide test conditions, then that may help in troubleshooting. One common area to check is the if you have setup a fractional frequency, you need to be sure to enable CP bleed current and set value to 115. For fractional frequencies, phase noise may degrade by 10dB without the bleed current set correctly. If you still require assistance, feel free to reach out to your local FAE and they can engage with product line for guidance.

Best Regards,

David

Hi. I have a similar problem. I can not reduce the phase noise in the lower offset values. For example, at 1kHz of frequency offset i have around -20dBc/Hz. I need to decrease this value to -50dBc/Hz. I am using a IF source between 2 and 2.4 GHz and i am using a 50 Mhz of Ref in to generate around 30 GHz of RF output using fractional N and lowest CP current. The bleed current does not make any effect over this values. How can i fix this problem? thank you!

Hi aocvm,

To help assist I'll need more information. Please provide block diagram of the setup, measurement data, phase noise the reference and IF sources, register map settings, etc. Also, is this on evaluation board or your board? If you can not post these to the forum, please work with your local FAE support; they will contact me if needed.

Thanks,

David

Hi. Of course. The block diagram set up and register map settings are exactly the same as the eval kit manual suggestion (page 4 and page 10 settings and PLL settings by default): https://www.analog.com/media/en/technical-documentation/user-guides/admv4530iq-evalz-4530if-evalz-ug-1759.pdf , an the test was over the same evaluation board. Referece phase noise = -70,86 dBc/Hz @1kH freq offset; IF phase noise = -102,13 dBc/Hz @1kHz freq offset. The best I could achieve was -32 dBc/Hz @1kHz freq offset. Tha you for the help!!

You will need a reference source with better phase noise. Additionally, you may want to run with a higher reference frequency so that the overall N value is lower, and therefore less phase noise from +20xlog(N).