reading serial flash SST25VF040B at 50MHz frequency
I am using SST25VF040B serial flash as memory for Digital to analog converter on an PCB designed. I have written into serial flash at 8MHz clock rate successfully. Next I tried to read same flash at 50MHz clock rate to provide flash's output as input data to Digital to analog converter. But getting unexpected signals when observed on mixed signal oscilloscope.
Once it read out correct data but after that it started to give some one zero kind of pulse at SO(serial output), even before the command to read flash completes. (though the one zero pattern is observed on flash'SO line i think its not the actual output of flash as when read same address location at much lower rate like 6MHz got corect output).
Also different signals captured on MSO are very noisy.
Not able to understand the behaviour. Please suggest what can be the possible reasons and how to solve it.