A quadruple-sampling second-order delta-sigma modulator

In this paper, a 1.8-V 3-bit quadruple-sampling delta-sigma modulator for audio application is presented. To performance high-resolution and low-cost modulator, a single opamp is used to complete the integration with four phases. Since the phase difference between any two succeeding clocks is 90 degrees, the sampling rate will be four times of clock frequency. The effective integration time can also be increased, and thus relaxing the requirements of opamp. From the simulation results, the proposed modulator achieves a peak SNDR of 104.5 dB for 20-kHz signal bandwidth under 1.8-V supply voltage and 2.56 MHz clock rate.