A 4.95mW 114dB SNDR delta-sigma modulator based on SC circuits for audio chip

A low-power high-resolution delta-sigma modulator for consumer audio chip is described. The modulator uses a 4
^th
-order CRFF topology based on switched-capacitor (SC) circuits with a 3-bit quantizer and pseudo data-weighted-averaging (PDWA) technique. To reduce power consumption, several techniques including a novel structure OTA, two-step summation, OTA-shared and an improved algorithm are proposed. The simulation results show that the proposed modulator achieves 114dB signal noise distortion ratio (SNDR) and costs 4.95mW with a 3.3V supply and 6.25MHz sampling frequency by Global-Foundries 0.18μm BCD process, which could be used for lowpower audio applications.