Continuous-Time Delta-Sigma Modulator with Time Domain Noise Coupling

This paper presents a design methodology to use time domain quantization noise information to further increase the order of the overall noise transfer function (NTF). Additional 2nd order NTF can be achieved by using the time domain quantization noise information that is inherently available in the noise shaped integrating quantizer (NSIQ). The time domain quantization noise is delayed through a voltage controlled delay line (VCDL) and coupled to the NSIQ itself using only two coupling resistors. Therefore, no additional digital-to-analog converter (DAC) is required to both extract the quantization noise and couple to the loop, which is necessary in traditional voltage domain noise coupling scheme. Mathematical analyses and MATLAB simulation results are provided to prove the efficiency of the proposed scheme.