An ultra low power sigma-delta modulator for hearing aid with double-sampling

A single-loop third-order switched-capacitor Sigma-Delta modulator for hearing aid application is presented. Double-Sampling is introduced to achieve a high performance with comparative low power consumption. The effect of capacitor mismatch is further discussed. To over come the switch-on problem under low-voltage, bootstrapping is adopted in this design. The modulator is implemented under SMIC0.13µm mix signal technology, the post simulation results indicates the modulator achieves 92-dB SNDR in 8 kHz signal bandwidth with an OSR of 128. The power consumption is 38uW under 1-V supply voltage and the chip core size is 0.25 mm2.