Abstract: A 5^th-order discrete-time (DT) single-loop single-bit-quantized ΣΔ modulator for audio application was designed.An improved Class-AB switched-OTA was proposed, which made the integrator achieve low power dissipation and high slew rate in low voltage.OTA worked at half of the clock cycle and effectively saved power of the modulator.Post simulation showed that the modulator achieved 97.6-dB SFDR and 87.3-dB SNDR.The total area was 0.4 mm².At 1-V power supply, the modulator consumed 260 μA current and the FoM was 286 fJ/c-step, which achieved the low-voltage low-power high-accuracy design target.