Frank wrote:

I have some digital waveforms, during the idle interval, it's zero, while in
active
mode, some patterns are output. This waveform is send through DAC (TI
DAC290x-EVM) and ADC (Analog AD9218). I am expecting a clean
zeros during the idle interval, however the ADC output are not. How can I
correct this problem?

How does it compare with the analog signal? What is the magnitude of
your error? IF there an AC component to your reading during idle? If
the error is small, it is probably system noise.

--
Thad