This paper presents a mixed-signal Viterbi decoder, which is suitable for a MB-OFDM UWB receiver. The decoder structure is based on a (2,1,7) convolutional code used in several UWB physical layer proposals. An analog processing core can be viewed as an alternative approach to the digital cores, which need advanced signal processing techniques to avoid the speed bottlenecks, e.g. in add-compare-select operation. By using a distributed trellis diagram and differential state metric update, the large path memory can be excluded from the decoder implementation. The accuracy of the proposed decoder is increased by combining the branch metric calculation with the 3-bit digital-to-analog converter at the decoder front-end.
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