EE 691WData Converter Design
Introduction
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Data Converters
SignalConditioning
ADC
MCU
DAC
PostProcessing
-Amplification-Anti-aliasingfilter
ex. Smoothing filter
Analog-to-Digital Converters(ADCs) provide an interface from the outside world to a computing systemDigital-to-Analog Converters(DACs)provide an interfacefrom a computing system to the outside world
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Why This Course on Data Converters?
Needed tointerface withthe physical worldData converters are everywhere – huge marketDemand for increasing data converter performance keeps growingSystem-on-a-chip applications mean that data converters are in truly mixed-signal applicationsData converters are typically the bleeding edge of analog/mixed-signal designData converters are notoriously difficult to design
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Why is data converter design difficult?
Need high precision from imprecise partsVery large, complicated systems, so simulation is difficult (and sometimes impossible)Many, many transistors – simulations can last hours/daysConvergence problemsThese are mixed-signal systemsNoiseCouplingOften require advanced processing and/or post-fabrication correctionLaser trimmingFusesInteraction with DSPsThese techniquescomplicate design/simulationDifferent from other analog systemsDeal with large signals (not small-signal modeling)
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Typical ADCs
Anti-aliasing filter tobandlimitthe signal
Converts from continuous-time to discrete-time(switched-capacitor techniques)
- Primary active element is the comparator- Often includes a DAC
- Creates the digital word- Provides error correction- Time synchrony
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Nyquist-Rate vs. Oversampled
Nyquist-RateSample at a rate close to theNyquistfrequency“Conventional” type of data convertersProvides the fastest sampling rates / bandwidthsOversampledSampling rate is much, much higher than theNyquistrate (typically at least 20 times higher)Often called “noise-shaping” circuitsProvides very high resolution
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Schedule
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Expectations Coming into Class
That you will participate!That you will actually do the readingEmphasis on doing, simulating, and creatingThat you remember (or can relearn) CadenceThat we will be able to find a time to meet outside of class time for brief project updates (for the final project)A willingness to experiment and search for answers
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Mechanics of Class
Several short announced quizzesCover recent reading materialUsually 15-20 minutesFocus on understanding concepts, as opposed to solving problemsReading synopsesShort write-ups on what you readIn-class summaries of a specific aspect/circuit (short explanatory presentation,usually just a few minutes)Statement saying that you actually did thereadingIn-classdiscussion and problemsClass time is a time for discussion, sharing ideas/designs, and getting questions answeredDesign reviews and project summariesEveryone participates!Please provide your input, suggestions, questions
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