AnsweredAssumed Answered

AD9956 LO and baseband mod generation external VCO configuration

Question asked by cwz on Nov 13, 2015
Latest reply on Nov 16, 2015 by KennyG

Hi there,


I would like to use the AD9956 in the LO and baseband modulation generation mode. As per Fig 24 in the datasheet, I would like my VCO to generate ~2,5GHz tone. However, here is my question:


Few things to make sure if VCO output is 2,5G:

     1) I have to set R appropriately so that SYSCLK does not exceed 400 MHz

     2) I have to set N appropriately so that PLLOSC does not exceed 200 MHz.


However, to set the R and N values, I first need to program the registers of the AD9956. So if that's the case, before I successfully program this values, how will the PLL loop behave, and subsequently, how will my VCO output behave?


Thanks in advance!