In this paper a 12 bits 50 kS/s micropower hybrid ADC is proposed for biomimetic microelectronic systems using 0.18 mum CMOS process. The hybrid ADC combines SAR and dual-slope architectures to achieve 12 bits, power consumption 60 muW, and small silicon die size. This hybrid ADC shows very good figure-of-merits (FOM) on both power consumption and silicon die size compared with conventional low power SAR ADC. A fully differential GmC integrator is proposed for the dual-slope operation with low voltage discrete-time CMFB.