I'm using an AD5725 in bipolar operation and am having an issue whenever it cross 0V. Whenever the polarity of the output changes, i get a rather large spike. I've included a scope shot of it. Any ideas on how to reduce/remove this behavior?
Are you using the similar schematic diagram as in Figure 28 of the AD5725 Data Sheet? Would you be able to provide more details (schematics, supplies, references, etc) so we could better help you with your issue?
I'm using an ADR4520 voltage reference which gets buffered through an inverting opamp stage to create the negative ref and then buffered again with another inverting opamp to create the positive reference. I'm using +/- 12V supplies with 0.1u decoupling for the DAC. I've done some more investigation and these spikes directly lineup with bit transitions. The more bits that transition during a DAC update, the larger the spike. I've tried adding some bulk capacitance to the supplies directly at the IC however that didn't seem to help.
This is called the output glitch. You are correct in stating that the more bits that transition during a DAC update, the larger the spike. We have specified this typical performance in Figure 26 of the AD5725 Data Sheet.
As for the reduction of the glitch, you could make an RC filter at the output. Take note that when you implement the RC filter, the DAC will have longer settling time at the output.
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