I'm confused about fref of SERDES PLL in AD9136

Hi xiaohexiang,

fREF term is used to refer to the frequency of the REFCLK fed into CLK+/- differential pins (pins 2 and 3). DACCLK is equal to fREF if DACCLK is sourced directly from CLK+/- (pins 2 and 3). If the DAC PLL is employed, the DACCLK is a multiple of fREF. The DACCLK is used to generate all internal clocks required by the DAC.

Regards,

Shine

Thank you for your answer.

But fREF term also seems to mean the reference of serdes pll. And I want to known the ralationship between the reference of serdes pll and DACCLK?

Hi xiaohexiang ,

Apologies for the delay. The relationship between fRef and DACCLK is indicated in Equation 2 in page 73 of the Rev D datasheet. As mentioned by ShineC above, the DACCLK is a multiple of fREF through clock multiplication, and DACCLK will be used to generate the internal clocks of the DAC, including the SERDES PLL. 

Regards,

Marco

Hi xiaohexiang ,

Apologies for the delay. The relationship between fRef and DACCLK is indicated in Equation 2 in page 73 of the Rev D datasheet. As mentioned by ShineC above, the DACCLK is a multiple of fREF through clock multiplication, and DACCLK will be used to generate the internal clocks of the DAC, including the SERDES PLL. 

Regards,

Marco