High-performance Viterbi decoder with circularly connected 2-D CNN unilateral cell array

A very-high-performance Viterbi decoder with a circularly connected two-dimensional analog cellular neural network (CNN) cell array is disclosed. In the proposed Viterbi decoder, the CNN cells with nonlinear unilateral connections are implemented with electronic circuits at nodes on a trellis diagram. The circuits are circularly connected, forming a cylindrical shape so that the cells of the last stage are connected to those of the first stage. Unilateral connections guide the information to flow circularly around the cylindrical surface. Such configuration enables the conceptually infinite length of the trellis diagram to be reduced to a circuit of limited size. The analog circuits does not require any analog-digital converters, which is the major cause of high power consumption and the quantization error. With the parallel analog processing structure, its decoding speed becomes very high. Also, the decoding mechanism using triggering wave of the CNN circuit does not require the path memory. Circuits for the proposed structure have been designed with HSPICE. Features of the proposed Viterbi decoder are compared with those of the conventional digital Viterbi decoder.