Hi,
We have a requirement for Data capture and down conversion using the ADC12DJ5200 DDC block. We are operating the ADCs in JMODE 15 with Fs = 4Gsps and the NCO frequency set to 1GHz. We are following the NCO Synchronization steps mentioned in Section 7.3.8.1.6. The SYSREF clock is continuous and AC coupled. So we have followed the procedure mention for AC coupled SYSREF. We have listed the registers and programing sequence below. But, despite that, we are not getting the data between two ADCs in-phase. Please check the programing sequence and let us know if it needs modification.
Note: With the same hardware, we were able to achieve synchronization in JMODE 20 (NCO Bypass mode) with 5.2Gsps sampling.
| step 1: | sysref calibration |
| x"002976", (ADC synchronization using SYSREF POS Values) | |
| step 2: | x"020000", -- Disable JESD |
| step 3: | x"006100", -- stop calibration |
| step 4: | write JMODE 15, NCO FREQ 1000 MHz, PHASE registers |
| step 5: | x"006101", -- start calibration |
| step 6: | x"020001", -- Enable JESD |
| step 7: | Program CAL_SOFT_TRIG 0 and then 1 |
| x"006C00", -- cal_soft_trig = 0 | |
| x"006C01", -- cal_soft_trig = 1 | |
| step 8: | start NCO synchronization by setting NCO_SYNC_NEXT to 1 at the same time at all ADCs |
| x"021902", --NCO_SYNC_ILA =0 (NCO SYNCHONIZATION REG) | |
| x"021903", --NCO_SYNC_ILA =1 (NCO SYNCHONIZATION REG) | |
| Note: | NCOA[1:0] and NCOB[1:0] are set to "00" always |
Note : We have tried writing NCO freq and Phase registers after enabling JESD also. But there is no synchronization however.
Regards,
Ayesha
