A 200 MHz 3.3 V BiCMOS class-IV partial-response analog Viterbi decoder

Analog Viterbi decoders have recently been shown to be viable alternatives to digital implementations. In fact a commercial realization for a class-IV partial-response maximum-likelihood magnetic read-channel has been reported. Analog Viterbi decoders offer the advantages of reduced power and size primarily due to the elimination of the A/D converter required in digital implementations. The analog Viterbi decoder described here offers the advantages of less complexity and improved robustness to circuit imperfections as compared to previously-reported realizations. This decoder was fabricated in a 0.8 μm BiCMOS process, consumes 30 mW from a 3.3V power supply while operating at an effective rate of 200 MSymbols/s, and has a core area of only 0.5 mm²