Our design has the AD9653 clocked by 100MHz,we found our board is very sensitive to external power supply, some times it works with one power supply and gives clean output but some time it has spikes on the output with another power supply. When it's not working, it has big offset outputs, 800 ~ 1200, while normally it has 100 ~ 250 offset.
Further investigation shows that if it is powered up with the 100MHz clock input disconnected, and later re-connect the clock, it will always work. But this doesn't make any sense, since the Data sheet says it needs a stable clock when powering up.
We are about to start the mass production, but do have some concerns about this, since we could not understand what's happening.
Any ideas will be greatly appreciated!
The AD9653 was configured as 1V internal reference, 2V span. SPI is not used, the SDIO/OLM, SCLK/DTP, CSB pins are strapped to OLM - AVDD, DTP- 10K to AGND, CSB -AVDD, for 2 lane, 1 frame, 16 bit , normal operation.