# A Low-Complexity Message Passing Algorithm for Reduced Routing Congestion in LDPC Decoders

Tinoosh Mohsenin

Dean Truong

Bevan Baas

*VLSI Computation Laboratory*

*Department of Electrical and Computer Engineering*

*University of California, Davis*

### Abstract:

A low-complexity message-passing algorithm, called
Split-Row Threshold, is used to implement low-density parity-check
(LDPC) decoders with reduced layout routing congestion. Five
LDPC decoders that are compatible with the 10GBASE-T standard
are implemented using MinSum Normalized and MinSum
Split-Row Threshold algorithms. All decoders are built using
a standard cell design flow and include all steps through the
generation of GDS II layout. An Spn = 16 decoder achieves
improvements in area, throughput, and energy efficiency of
4.1 times, 3.3 times, and 4.8 times, respectively, compared to a
MinSum Normalized implementation. Postlayout results show
that a fully parallel Spn = 16 decoder in 65-nm CMOS operates
at 195 MHz at 1.3 V with an average throughput of 92.8 Gbits/s
with early termination enabled. Low-power operation at 0.7 V
gives a worst case throughput of 6.5 Gbits/s just above the
10GBASE-T requirement and an estimated average power of 62 mW,
resulting in 9.5 pJ/bit. At 0.7 V with early termination enabled,
the throughput is 16.6 Gbits/s, and the energy is 3.7 pJ/bit,
which is 5.8 lower than the previously reported lowest energy
per bit. The decoder area is 4.84 mm?? with a final postlayout area
utilization of 97%.

### Paper

### Reference

Mohsenin, T.; Truong, D.N.; Baas, B.M.; , "A Low-Complexity Message-Passing Algorithm for Reduced Routing Congestion in LDPC Decoders,"
*Circuits and Systems I: Regular Papers, IEEE Transactions on*, vol.57, no.5, pp.1048-1061, May 2010

### BibTeX Entry

@ARTICLE{Mohsenin:TCASI,
author={Mohsenin, T. and Truong, D.N. and Baas, B.M.},
journal={Circuits and Systems I: Regular Papers, IEEE Transactions on},
title={A Low-Complexity Message-Passing Algorithm for Reduced Routing Congestion in {LDPC} Decoders},
year={2010},
month={May.},
volume={57},
number={5},
pages={1048-1061},
doi={10.1109/TCSI.2010.2046957},
ISSN={1549-8328}
}

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Last update: Sep. 27, 2010