AD9914 multi-chip synchronization questions

Question

Hi 
 I am planning to use 9 AD9914 chips as signal generators for a wideband system (1 main chip and 8 subordinate chips) to generate RF signals between 0.1-1.4 GHz and will need to synchronize these using an external clock generator connected to the main chip. 
 Reading through the datasheet there's no mention of the system clock frequency being limited while using an external reference signal but reading through the AD9914 FAQ found here: What is the difference between the AD9914 and AD9915? it mentions AD9914 being limited to 2.5 GHz when using the multi-chip sync. Would this mean i am effectively locked between using a REF CLK of between 500 MHz and 2.5 GHz? 
 I also wonder if it is possible to control multiple AD9914 using one microprocessor and the chip select bar or if it is recommended to use one microprocessor per AD9914 instead when controlling the frequency and phase of the outgoing signals?

Jules.Nikko · Accepted Answer

Hi Gustav677 , 
 Yes, it is limited to 2.5 GHz as there will be inconsistencies when proceeding at higher frequency. This is also the reason why AD9915 was derived from AD9914 to ensure synchronization and certain application notes (AN-1254) discusses this. 
 As per AN1254, it is possible to use 1 microprocessor or let's say device to control the IO_Update for all the devices for it to have a synchronized IO_Update signals. Controlling CS in that sense will also be possible. 
 
 All the best, 
 Jules)

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AD9914 multi-chip synchronization questions