Paper presentation Ultra-Portable Devices Paper: S. Hong, W. E. - - PowerPoint PPT Presentation

Paper presentation – Ultra-Portable Devices

Paper: Presented by:

• S. Hong, W. E. Stark.

Decoding Performance and Complexity Analysis for Analog and Digital Channel Decoders.

Vehicular Technology Conference (VTC), May 2001, vol. 2, pages 1277-1281. Reza Meraji

2010-02-03 1 Paper Presentation - Ultra Portable Devices

Outline

• Decoder Models

– Digital Viterbi decoder – Analog Viterbi decoder

• Basic read/write analog memory model
• Performance Evaluations

– Noise sources in decoders – Data access and path memory length

• Comparisons of energy and area
• Summary and conclusion

2010-02-03 2 Paper Presentation - Ultra Portable Devices

Digital and Analog Processing System Models

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Decoder Architecture Models for Convolutional Codes

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Main Processing Units

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Analog Memory Model

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Memory Read Access (Scaling)

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Noise Sources in Decoders

• Digital

– Quantization noise – Finite wordlength

• Analog

– Noise due to nonlinearity of the read and write amplifiers – Noise due to charge leakage (strong function of time and temperature) – Noise due to charge sharing (capacitor mismatches)

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Analog Decoder Performance:

as a function of capacitor sizes

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Analog Decoder Performance:

as a function of overall amplifier gain deviation

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Data Access and Path Memory Length

• Data access

– Too many memory access times: Data value deterioration – Memory not accessed quickly enough: information leaks as electric charge

• Path memory length:

– Small dynamic range (limited supply voltage) – Computational overflow for a long path memory length

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Power Dissipation in Decoders

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• Digital:

– Switching power dissipation – Short-circuit current power

• Analog:

– Mostly because of biasing current

• Memory access power dissipation applies for both

Energy and Area Comparisons

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Summary

• Analog circuits: a solution for small size, high speed and

low-power signal processing applications

• System performance distortion due to imperfect

characteristics of analog citcuits

• Undesirable effects of the analog memory on the

decoder performance

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