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ADF5901 Dev board routed programming question

Hello all,

I am looking at the ADF5901 development board datasheet and I had a few questions about some of the routed connections. 

In the datasheet above, I'm focusing on the connections between the SPD programming board to the ADF4159 and ADF5901.  The ADF4159 VDVDD is listed as 1.8 in its own data sheet. I assume the resistors between SPI_CLK (R11 and R28) CLK_PLL are there as a voltage divider from the SPD output 3.3 to 1.8? Can those resistor values change as long as the ratio remains the same?

Also, does the resistor between SPI_CLK (R46) CLK_TX need to be there? Is it serving as a current limit? 

Thanks in advance!


Edited by wsapia
[edited by: wsapia at 1:29 PM (GMT 0) on 7 May 2020]