A rounded value is sent to the DAC via a microcontroller and represents frequency. I have measured each step of the MCP4921 DAC output, and compared it to the ideal rounded integer to see how much error is present. The value sent out is from an exponential calculation so the amount of descrete steps grows exponentially between each DAC data point. I understand that the DNL error has bigger effect when there are less discrete steps ,therefore there should be less error at higher frequencies. but looking at the graph, the actual values seems to be growing at higher DAC points, not tending towards the ideal voltage. what could be causing this? orange is the actual measurements, grey is the rounded value (ideal)
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