I'm working with a AD9833. I have a 1MHz oscillator for the master clock. It works fine at low frequencies (<10kHz). But when I try to go higher the output looks like a staircase (steps). This does not happens at a specific frequency though. It gets worst as I increase the frequency. The triangular wave does the same thing. The master clock frequency looks like a perfect square wave. The design is in a PCB with connection to a breadboard. No ground planes at all in the PCB. Is this a noise issue? or Am I missing something more fundamental?