DAC38J84: Complex Mixer Block and NCO setting

min hu

Intellectual 990 points

Part Number: DAC38J84

Mode:4421,data_reate=312.5Msps,8x interpolation,DAC_CLK=2500MHz(external)

K=16,ref_clk=156.25MHz,SYSREF=19.53125

Bypass Mixer Block,DAC output is about 10MHz single tone(IQ):FIG1

Enable Mixer Block with Course Mixer Mode = Fs/8,Output is right：FIG2

I would like to use NCO Block,So Enable Mixer Block,Course Mixer=Bypass,NCO Enable:register Config2=0x20D0,

but the output is not what expected?

my SYSREF is continuous,so NCO Accu syncing source can not be 'SYSREF',I tried all the other configurations,NCO seems not working right.

Anything i missed?

Thanks,

Hoo

over 8 years ago

0 min hu over 8 years ago

Intellectual 990 points

DAC input data is Offset-Binary

DAC output is not what expected:

I use the GUI tool to help me with the register settings:

config2=0x20D0;

config13=0x0400;

config31=0x1140;

0 jim s over 8 years ago in reply to min hu

TI__Guru* 91947 points

Min,

If you are using the TSW14J56EVM, you need to set the DAC option to 2's Complement, not Offset Binary if you are using the default settings of the DAC.

Config2 should be 0x2052

Config13 should be 0x400

Config31 should be 0x9980

Regards,

Jim

Data converters

Data converters forum

DAC38J84: Complex Mixer Block and NCO setting