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Introduction of Analog to Introduction of Analog to Digital ConverterDigital Converter
YZU EEVLSI Lab 3524Yan-Chu Chou
2 Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
OutlineOutline
IntroductionPrinciple
Structure
Conclusion
Reference
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Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
IntroductionIntroduction
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DigitalProcessor
Prefilter Sample/Hold Quantizer Encoder
General block diagram for an ADC
Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
Classification of ADC Classification of ADC ArchitecturesArchitectures
Conversion Rate Nequist ADCs Oversampled ADCsSlow Integrating(serial) Very high
resolution>14bits
Medium Successive approximation
1-bit PipelineAlgorithmic
Fast Flash Low resolution>6bits
Multiple-bit pipeline
Folding and interpolating
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Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
PrinciplePrinciple
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Static Characterization of ADCs•Offset error:the horizontal difference between this line and the infinite resolution characteristic that passes through the origin•Gain error:a difference between the actual characteristic,and the infinite resolution characteristic,which is proportional to the magnitude of the input voltage•Integral nonlinearity(INL):the maximum difference between the actual finite resolution characteristic and the ideal finite resolution characteristic measured vertically in percent or LSBs•Differential nonlinearity(DNL):defined as a measure of the separation between adjacent codes measured at each vertical step in percent or LSBs
Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
Offset errorOffset error
Example of offset error for a 3-bit ADC5
Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
Gain errorGain error
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Example of gain error for a 3-bit ADC
Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
INL and DNLINL and DNL
Example of INL and DNL for a 3-bit ADC
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Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
Flash A/D ConverterFlash A/D Converter
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Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
Interpolating A/D Interpolating A/D ConverterConverter
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Introduction of Analog to Digital ConverterIntroduction of Analog to Digital Converter
ConclusionConclusion
The ADC by nature must be sampled. It is not possible to continuously convert the incoming analog signal to a digital output code.The ADC is a sampled-data circuit.
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