Hello TI forum members,
I am currently working on a project where I need to perform frequency hopping using four LMX2820 PLLs while ensuring their phase synchronization. Specifically, I am aiming for a frequency switchover time of less than 200 microseconds. The phase synchronization requirement falls under Category 3.
I would greatly appreciate any guidance or suggestions on how to achieve this task effectively. Here are a few specific points I would like to address:
1. Is it mandatory to perform VCO calibration after each frequency change for Category 3? Are there any workarounds? I am curious to know whether I would need to re-synchronize the PLLs if I perform an instant calibration or fully assisted calibration. I am assuming that the synchronisation will not be maintained while using fully assisted calibration. Are there any considerations or steps I should take to maintain phase synchronization after calibration?
2. In order to optimize the frequency settling time after synchronisation (in order to reduce the MASH_RST_COUNT value), I am open to increasing the loop bandwidth. However, it is important to ensure that the spurious levels stay under -50 dBc. Could you provide any suggestions or guidelines on adjusting the loop bandwidth while keeping the spurious levels within the desired range? I am planning to use an fOSCIN of 200MHz. Are there any other ways to improve the frequency settling time after the sync event?
Any insights or recommendations on this topic would be greatly appreciated.
