Decreasing the effects of BJT´s parasitics of computing cells for analog decoders

This paper presents an analog decoder computing cell less sensitive to bipolar junction transistor (BJT) parasitic elements. Unlike customary cells, the proposed cell does not invert the output probabilities ranking, hence limiting the wrong decoding outcome. This is achieved with a slight complexity increase as only two diodes are added to the basic computing cell. It is also shown that the proposed cell can improve the decoding performance even for large biasing current, opening the way to improve the decoding convergence of an analog BiCMOS decoder. Simulation results are shown for a 0.25-μm BiCMOS process from NXP with minimal size transistors.