On the evaluation board, we can confirm the phase noise in Fig. 2 with the loop filter in Fig. 1 (almost agrees with the simulation).
With the loop filter in Figure 3, the result is Figure 4, which is not the same as the simulation result.
What do you think is the cause of this?
(Why is it equal to the actual measurement in Fig. 1 and not the same in Fig. 3?)
There is a possibility that the parts constant of the loop filter is different, so I replaced it several times, but the result is the same.
Is it because the constant setting of the loop filter is bad?
The purpose is to set the 100kHz loop bandwidth to about 10kHz and improve the integrated value of phase noise.
Attached is the phase noise data of 120M REF used in the simulation, so please give us some advice.
Regards,
Akihiko Yokouchi/
Fig.1
Fig.2
Fig.3
Fig.4
120M REF data
10 -92
20 -92
30 -92
50 -92
70 -92
100 -92
200 -102
300 -109
500 -119
700 -125
1000 -131
2000 -138
3000 -139.3
5000 -140
7000 -140.5
10000 -141
20000 -142
30000 -143
50000 -144
70000 -145
100000 -145.5
200000 -147
300000 -148
500000 -149
700000 -150
1000000 -151
