A　large　number　of　redundant　signals　will　be　generated　when　the　traditional　Nyquist　sampling　method　is　used　to　acquire　a　biological　signal,　leading　to　a　system＇s　energy　loss.　A　new　level-crossing　analog-to-digital　converter　(LC-ADC)　with　non-uniform　sampling　and　fixed　window　structure　is　presented,　with　fewer　data　and　low　power　consumption　features.　The　circuit　uses　a　6-bit　capacitive　DAC　to　quantize　the　input　signal,　avoiding　the　error　accumulation　of　the　1-bit　capacitive　DAC　structure,　and　a　nanoamp　CMOS　current　bias　circuit　to　provide　a　very　low　quiescent　current　for　the　comparator,　further　reducing　power　consumption.　The　structure　was　verified　in　a　0.18μm　CMOS　technology.　The　results　indicate　that　the　total　power　dissipation　is　0.26uw@500Hz,　the　signal-to-noise　distortion　ratio　(SNDR)　is　59dB@500Hz,　and　ENOB　reached　9.51bit,　which　is　suitable　for　the　acquisition　of　low-frequency　biological　signals.　　©　Published　under　licence　by　IOP　Publishing　Ltd.