Decoding a family of dense codes using the sum-product algorithm and subthreshold PMOS

Jorge Ernesto Perez Chamorro (1) , Fabrice Seguin (2, 1) , Cyril Lahuec (2, 1) , Gérald Le Mestre (2, 1) , Michel Jezequel (2, 1)

1 ELEC - Département Electronique
2 Lab-STICC_TB_CACS_IAS

Cortex codes are a family of block codes with good minimum distance properties whose parity-check matrices are very dense. Digital implementations of Cortex decoders using standard decoding algorithms have not shown an acceptable performance. Motivated by the encoder structure, a new bipartite graph is introduced and exemplified for the Cortex construction of the extended Hamming code. The Cortex graph has longer girth and approximately 80% less cycles than the Tanner graph. A Cortex and an LDPC-like decoder were implemented for the same code using identical PMOS-based Gilbert multipliers. This makes them the first reported analog decoders using mainly PMOS transistors. The Cortex outperforms the LDPC-like decoder in Bit Error Rate and at the same time saves 44% of die surface. The results are supported using data from a test chip designed for a 0.25 um CMOS process.

Mots clés: Analogue decoding; CMOS analogue integrated circuits; Channel coding

Domaines: Electronique; Traitement du signal et de l'image [eess.SP]

Jorge Ernesto Perez Chamorro, Fabrice Seguin, Cyril Lahuec, Gérald Le Mestre, Michel Jezequel. Decoding a family of dense codes using the sum-product algorithm and subthreshold PMOS. IEEE International Symposium on Circuits And Systems, Taiwan, May 2009, Taipei, Taiwan. pp.2685 - 2688. ⟨hal-01853651⟩