An all-analog CMOS implementation of a turbo decoder for hard-disk drive read channels

In this work we present a full analog turbo decoder for hard-disk EPR-IV read channels in CMOS technology. The design is based on a current-mode approach developed by Loeliger et al. [1], for the analog implementation of sum-product algorithms. The circuits main attractions are the coding gain offered by turbo codes over the uncoded EPR-IV channel, and the relative simplicity and power efficiency of the analog approach over the digital approach. The circuit is developed in a 0.18 μm CMOS technology and operates at a 1.8 V power supply, with a total simulated power consumption (including peripheral circuitry) of about 650 mW at 400 Mb/s.