Analog Circuits for Symbol-Likelihood Computation

New analog circuits are presented to convert the output of a matched filter into symbol-and bit-likelihoods suitable as input to analog decoders for error correcting codes. The new circuits can be adapted to many constellations including pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM) and for arbitrary bit-to-symbol mappings. In contrast to a previously published circuit these new circuits compute exact probabilities and they are more versatile.