This paper presents the effect of BJTs’ parasitic elements on the decoding performance of a BiCMOS analog decoder. The transistor’s parasitic effects are taken into account to develop a more accurate behavioral model of the computing nodes. The model is applied to double-binary 0.25-μm BiCMOS analog decoders. Behavioral simulations show that the BJTs parasitic elements deteriorate the error correcting performance of a stand-alone APP decoder by 0.5dB compared with the ideal BER. In a turbo scheme, the loss is reduced to 0.2dB for BER smaller than 10−2. A simple solution based on an NMOS amplifier is proposed to counterbalance the dominant parasitic element. The amplifier reduces the degradation by 0.2dB for the APP decoder. However, the turbo decoder is improved only for a BER above 10−2.