DAC Zero-Order Hold Models
This article provides two simple time-domain models of a DAC’s zero-order hold. These models will allow us to find time and frequency domain approximations of DAC outputs, and simulate analog filtering of those outputs. Developing the models is also a good way to learn about the DAC ZOH function.
Summary
This blog presents two simple time-domain models of a DAC's zero-order hold (ZOH), showing how to derive time- and frequency-domain approximations of DAC outputs. It explains how those models can be used to simulate analog filtering and to reason about reconstruction/anti-imaging effects.
Key Takeaways
- Derive two time-domain ZOH models that represent the DAC output as a sequence of held rectangular pulses.
- Approximate the ZOH frequency response (sinc-shaped effect) and predict spectral images introduced by the hold.
- Simulate the effect of analog reconstruction/anti-imaging filters on DAC outputs using the time-domain models.
- Quantify how hold duration and sample rate affect time-domain ringing and frequency-domain attenuation of harmonics.
Who Should Read This
DSP engineers or graduate students with interest in DAC behavior who need practical models to design reconstruction filters and analyze spectral effects.
TimelessIntermediate
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