Other Parts Discussed in Thread: LMX1204, , ADC12DJ5200RF, LMX2595, LMX2572, LMX2595EVM
Hi, for my current project I need a fractional PLL based clock generator design for driving several ADC12DJ5200RF. The idea is to use a LMX2572 or a LMX2595 fpll to drive a LMX1204 which would generate all the JESD204B/C related signals and ADC clocks. I have the relevant EVM from Texas Instruments to evaluate the performance before we use these in actual design, however I have some issues with the performance I am getting from the LMX1204EVM.
Below is a spectrum of what the LMX2595EVM generated clock of 5120Mhz looks like. I am satisfied with this performance, apart from the overtones there are no other spurs (at least from what this old spectrum analyzer can see). I have terminated RFOutAM and I am measuring RFOutAP here with a 50 Ohm Coax to the SA. The power level is somewhere between 5-6 dBm. The PLL is properly locked and indicated by the LED on the EVM.
However, when I feed this signal into CLKINP (CLKINN is terminated) and measure the output of the LMX1204EVM in buffer mode I get really poor spurious performance and I don't know why. I am measuring on CLK0P and I have terminated CLK0N.
This is the settings I use for the LMX1204EVM in TICS PRO:
Is there something I am doing wrong in the settings for the LMX1204EVM or my setup? Is this spurious performance typical and expected of the LMX1204?
