Analog Decoding of Trellis Coded Modulation for Multi-level Flash Memories

Trellis coded modulation (TCM) is a potential candidate for error correction in multilevel flash memories. TCM typically requires probabilistic decoding algorithms (e.g. BCJR), that can be conveniently implemented in the analog domain. In this work, we study the feasibility and complexity of the analog approach, proposing transistor-level solutions for the building blocks of the decoder. In the case of a TCM designed for an effective storage density of 3 information bits/cell, an analog decoder for a 196-bit field features an estimated current draw of <0.5 mA and area overhead of <0.45 mm2.