Design, Simulation, and Implementation of a CMOS Analog Decoder for (480,240) Low-Density Parity-Check Code

The analog low-density parity-check (LDPC) decoder, which is a specific application of the probabilistic computing, is considered to be a promising solution for power-constrained applications. However, due to the lack of efficient electronic design automation tools and reliable circuit model, the analog LDPC decoders suffer from costly hand-craft design cycle, and are unable to provide enough coding gains for practical applications. In this paper, we present an implementation of a (480,240) CMOS analog LDPC decoder, which is the longest implemented code to date using the analog approach. We first propose an analog LDPC decoder architecture, which is constructed by the reusable modules and can significantly reduce the hardware complexity. And then, we present a mixed behavioral and structural model for the analog LDPC decoding circuits, which can reliably and efficiently predict the error-correcting performance. Finally, the experimental results show that the decoder prototype, which is fabricated in a 0.35-μm CMOS technology, can achieve a throughput higher than 50 Mbps with the power consumption of 86.3 mW for the decoder core, and can offer a superior 6.3-dB coding gain at the bit error rate of 10-6 when the tested throughput is 5 Mbps. The proposed analog LDPC decoder is suitable for the power-limited applications with moderate throughput and certain coding gains.