Partecipants: Marco, Eleonora, Yuhang, Matteo

We mount in a NIM box the PLL board described in the logbook entry 847. The photo of the box are 'pllboxfrontend.png' and 'pllboxtop.png'.

Description of the front-end:

- 2 SMA connector for the two input beat note and RF channel from DDS board not amplified

- Lemo connector (output) label MUX is a chnnel digitally configurable from the software use for diagnostic purposes (RF monitor, Beat monitor, Lock detect, etc)

- Lemo connector (output) label Fast is the correction singnal sent to lazer PZT, it can be activated or not using a switch mounted on the front panel

- Lemo connector (output) label Slow is the correction signal sent to laser PLT, it can be activated or not using a switch mounted on the front panel

Test of the board using AUX2 as slave laser (fig 'aux2lasrslave.pdf')

We tested the long term stability during the night ant the day later we found the PLL still locked 

We measure the PLL phase noise in three different condition (charge pump current: 4.375mA):

- MLfree running (rampe auto swithced off) rms phase noise: 4.9mrad

- ML free running (rampe auto switched on) rms phase noise: 10.6mrad

- ML non free running (filter cavity locked) rms phase noise: 16.7mrad

Test of the board using AUX1 as slave laser (fig 'aux1lasrslave.pdf')

We measure the PLL phase noise in three different condition  (charge pump current: 3.75mA):

- MLfree running (rampe auto swithced off) rms phase noise: 5.5mrad

- ML free running (rampe auto switched on) rms phase noise: 14.9mrad

- ML non free running (filter cavity locked) rms phase noise: 15mrad

For both the servo loop we noticed that the output voltage of the rampe auto is high enough to increase the ML frequency noise.

Moreover the noise reduction due to the filter cavity locking between 100 Hz and 12-15 kHz is visible in both the servo loop. 

The rampe auto noise is predominant at frequencies above the unitary gain bandwidth of the filter cavity servo loop