Part Number: LMX2594PSEVM
I have a design question about clock synchronization and ADC/DAC synchronization across cards
We are designing a ADC/DAC card that will transmit a signal and then receive the return signal of a frequency comb. the return signal will be phase and amplitude shifted due to the sensors on the transmitted side.
We are currently making 4 identical cards that will send and read back frequency signals from different sensors.
I am considering however the implications of these four cards not being synchronized
There is at the moment a thought that we want to have the option of an external synchronized clock, but we have not implemented it yet at the moment we have a clock tree using the LMK/LMX and a clean reference clock that generates two 5Ghz clocks for the ADC and the DAC but we do not have synchronization across cards
1. If the sensors are distinct does it maybe not matter that they are not synchronized? Even though the same frequencies are sent to each sensor. Will not being synchronized across the cards make it difficult to distinguish between phase noise and actual phase shift in the return signal? Or just make it hard to compare across sensors?
2. If we want the option of an external clock so we can have the option of synchronization, does it make sense to repeat the same circuitry over and over on four cards or could we use one clock card and distribute that across cards through a backplane type board? Or would not having a very clean reference clock on each card make it difficult to achieve the low noise we might need on each set of ADC/DACs
3. If we do only use only clock card, could that be more easily be used to synchronize other things such as a power card that has switch mode power supplies? as well as all the ADCs/DACs?
Maybe too detailed of questions, but essentially right now we have no synchronization across cards or sensors, and I want to better understand the risks of doing so.
We are currently using the attached EVM boards to implement a prototype with the ADC/DAC sample clock at 5GhzADC_Datasheet_EVM.pdf DAC39RF10EVM_User_Guide.pdf