Tool/software:
Hello everyone.
While working on a system (Avnet Microzed card connected to a PCB with several modules, including two ti DAC3484), I got additional phase noise in my datapath.
While working with data of zeros and testing the NCO module of the DAC's, I've noticed a Phase addition in the NCO. My clock configuration is:
f_DACCLK=1GHz, Interpolation=8, DATACLK= 125MHz, f_OSTR = 15.625MHz, SYNC off, f_FRAME=7.8125MHz.
while working with DATA of zeros, this is my DAC configuration:
Configuring CONFIG0 = 0x349F
Configuring CONFIG2 = 0xF052
Configuring CONFIG18 (phase_offsetAB(15:0))= 0x0000
Configuring CONFIG19 (phase_offsetAB(15:0))= 0x0000
Configuring CONFIG20 (phase_addAB(15:0))= 0x3333
Configuring CONFIG21 (phase_addAB(31:16))= 0x3333
Configuring CONFIG22 (phase_addCD(15:0))= 0x3333
Configuring CONFIG23 (phase_addCD(31:16))= 0x3333
Configuring CONFIG24 = 0x280B (PLL bypassed)
Configuring CONFIG25 = 0x6074
Configuring CONFIG26 = 0x7820 (PLL sleeping)
Configuring CONFIG27 = 0x0800
Configuring CONFIG330 = 0x9999
Configuring CONFIG31 = 0xAA90
Configuring CONFIG32 = 0xCC00
I got some snapshots from my scope:
When I look at the DAC3484 datasheet, I expect the NCO to output signals with 90 degrees phase from each other within the two paths (AB and CD).
Why am I getting this Phase offset?
Thank you in advance,
Tomer
