1. A crossing input signal modulator, comprising: a positive path block comprising a first integrator firstly integrating a first input signal and a feedback signal of an output signal of the positive path block to transfer an output signal of the first integrator to a second integrator, and the second integrator secondly integrating the output signal of the first integrator and a second input signal; and a negative path block comprising a third integrator firstly integrating the second input signal and a feedback signal of an output signal of the negative path block to transfer an output signal of the third integrator to a fourth integrator, and the fourth integrator secondly integrating the output signal of the third integrator and the first input signal.