Paper presentation Ultra-Portable Devices Paper: CH. Winstead, N. - PowerPoint PPT Presentation

Paper presentation � Ultra-Portable Devices Paper: CH. Winstead, N. Nguyen, V. Gaudet, CH. Schlegel. Low-Voltage CMOS Circuits for Analog Iterative Decoders. IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS, REGULAR PAPERS, vol. 53, no. 4, April 2006, pages 829-841. Presented by: Reza Meraji 2010-02-03 Paper Presentation - Ultra Portable Devices 1

Outline � Decoding Circuits based on sum-product algorithm � Canonical topology � Low voltage topology � Decoder architectures � Trellis � Tanner Graph � Example decoder implementations � Performance results 2010-02-03 Paper Presentation - Ultra Portable Devices 2

Sum-Product Algorithm 2010-02-03 Paper Presentation - Ultra Portable Devices 3

Canonical Sum-Product Circuit 2010-02-03 Paper Presentation - Ultra Portable Devices 4

Canonical Sum-Product Circuit: Source Connected Transistor Array 2010-02-03 Paper Presentation - Ultra Portable Devices 5

Re-normalization Circuit 2010-02-03 Paper Presentation - Ultra Portable Devices 6

A Slice of the Canonical Topology 2010-02-03 Paper Presentation - Ultra Portable Devices 7

Low Voltage Sum-Product Circuit Topology 2010-02-03 Paper Presentation - Ultra Portable Devices 8

Allowable Supply Voltages 2010-02-03 Paper Presentation - Ultra Portable Devices 9

Difference in Minimum Supply Voltage 2010-02-03 Paper Presentation - Ultra Portable Devices 10

Decoder Architectures: Trellis Decoders (Hamming Code) 2010-02-03 Paper Presentation - Ultra Portable Devices 11

Low-Voltage Circuit for Trellis Decoding 2010-02-03 Paper Presentation - Ultra Portable Devices 12

LDPC (Tanner Graph) Decoders Tanner graph for an (8,4) Hamming code Implementation of equality and parity-check nodes for LDPC-style decoders 2010-02-03 Paper Presentation - Ultra Portable Devices 13

Die micro photograph of chip: showing the factor graph decoder , the Trellis decoder, and the I/O interfaces 2010-02-03 Paper Presentation - Ultra Portable Devices 14

Decoder Implementations Summary 2010-02-03 Paper Presentation - Ultra Portable Devices 15

Serial I/O Interface 2010-02-03 Paper Presentation - Ultra Portable Devices 16

I/O Timing: Transient Response 2010-02-03 Paper Presentation - Ultra Portable Devices 17

Experimental Setup 2010-02-03 Paper Presentation - Ultra Portable Devices 18

Performance results: for the Tanner graph (TG) and T rellis (TR) decoders 2010-02-03 Paper Presentation - Ultra Portable Devices 19

Measured results: Showing performance as a function of supply voltage and speed for the Tanner graph decoder 2010-02-03 Paper Presentation - Ultra Portable Devices 20

Measured results: Showing performance as a function of supply voltage and speed for the Trellis graph decoder 2010-02-03 Paper Presentation - Ultra Portable Devices 21

Energy Efficiency Figures: Of Digital (top 2) and Analog Decoders (bottom 4) 2010-02-03 Paper Presentation - Ultra Portable Devices 22

Comparison of Eb/N0 losses: For the Tanner graph (TG) and T rellis (TR) decoders at different Vdd as a function of clock speed 2010-02-03 Paper Presentation - Ultra Portable Devices 23

Summary � Overview of low power CMOS analog circuits f or iterative decoding � A new topology for reducing supply voltage by at least 0.4 V � Proposed topology used to implement two types of decoders � The Trellis decoder achieved the lowest energy per bit of any reported iterative decoder 2010-02-03 Paper Presentation - Ultra Portable Devices 24