This paper presents the time-domain analysis of a fully differential incremental ΔΣ modulator. Particularly, the influence of the bipolar feedback signal on the quantization noise of the modulator is analyzed, which is overlooked in most IDC designs. Based on the analysis, an initial feedback zeroing scheme is introduced to decrease the quantization noise of the modulator. Moreover, the maximum number of output codeword that can be produced by the modulator is mathematically derived. Following the derivation, a control scheme is proposed to achieve 1.5-bit effective feedback without changing the quantizer and D/A topology. By applying the initial feedback zeroing and 1.5-bit feedback technique, the quantization noise can be decreased by 4× for the 1st- and 2nd-order modulators analyzed in this paper, with very minor modifications on the modulator’s original digital controllers.