A 15.8 pJ/bit/iter quasi-cyclic LDPC decoder for IEEE 802.11n in 90 nm CMOS

We present a low-power quasi-cyclic (QC) low density parity check (LDPC) decoder that meets the throughput requirements of the highest-rate (600 Mbps) modes of the IEEE 802.11n WLAN standard. The design is based on the layered offset-min-sum algorithm and is runtime-programmable to process different code matrices (including all rates and block lengths specified by IEEE 802.11n). The register-transfer-level implementation has been optimized for best energy efficiency. The corresponding 90 nm CMOS ASIC has a core area of 1.77 mm² and achieves a maximum throughput of 680 Mbps at 346 MHz clock frequency and 10 decoding iterations. The measured energy efficiency is 15.8pJ/bit/iteration at a nominal operating voltage of 1.0 V.