Part Number: DAC39RF10 Other Parts Discussed in Thread: ADC12DJ3200 Tool/software: We are using LMX2615 for DAC39RF10 and ADC12DJ3200. LMX2615's Output clocks are 8388.608MHz for DAC and 2097.152MHz for ADC. Under low temperature around 0 degree C, there is below issue. Our board has the spurious about 35dBc at +-2.08MHz from fundamental frequency of DAC. Of course, if DAC output frequency is changed, the spurious occurs around +/- 2.08MHz at that changed frequency. Also, We measured the 8388.608MHz between LMX2615 and DAC39RF10. There are the spurious about -80dBm at +-2.08MHz from fundamental frequency of DAC. We controlled the power down of DAC(controlled by SPI : DAC Register 0x0002 0x03), then the spurious has been eliminated. We are digging the DAC's input clock buffer power(VDDCLK10)and core clock power power(VDDCLK18) noise issue and also pull up matching circuit between LMX2615 and DAC39RF10. Do you have any clue for this issue? please refer the below schematic.
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