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AFE7444EVM: AFE7444 Ref clock

ganesh singh1
Intellectual 400 points
Part Number: AFE7444EVM
Other Parts Discussed in Thread: AFE7444

Hi ,

I want to increase the AFE ref clock to 384 MHz. I tried it, but Internal VCO seems to be not tuned properly. I make 16x interpolation and the Clockout of AFE is not 2.048GHz. 

As per theory, it should be 384*16 = 6.144 GHz ( DAC Clock) and ADC clock = DAC clock/3 = 2.048 GHz. This should be the same as Clock out of AFE. 

Can you please let me know if it is possible to do that in AFE7444 EVM?

Right Now I am programming LMK of AFE with Prescaler 5 and M value at 5 so the VCO Freq will be 3.072 GHz. Then I divide it by 8 to get the AFE REF clock to 384 MHz.

Please help me in this regard if possible.

With regards,

Ganesh Singh

  • 0
    TI__Genius 10505 points

    Hi Ganesh,

    In AFE7444, the low VCO is tuned to a target center frequency of 5.89824 GHz, and the high VCO is tuned to a target center frequency of 8.84736 GHz. All characterization in internal PLL mode of AFE7444 device is done at 5.89824 or 8.84736 GHz VCO frequencies. The EVM GUI is also coded to program these frequencies. 

    It might be possible to configure in clocking scheme that are you suggested above. However you have to manually create the SPI configuration files for LMK as there could be more settings that need to be done to use 3.072 GHz VCO in LMK. You can use TICS Pro to get SPI config files. 

    The AFE79xx family devices are more flexible in terms of configuration and also better than AFE7444 in almost all specifications. I suggest that you look into AFE79xx if need an AFE in internal PLL mode at different VCO frequencies. 

    Regards,

    Vijay