Signal detection circuit with surge noise removing function and method thereof

A signal detecting circuit is used for detecting whether the differential input signal amplitude is smaller than the standard size to generate a digitalized output signal to reflect the signal clamping condition of the input signal. The signal detecting circuit comprises a reference voltage generator for generating the reference voltage, the common mode voltage of which searches the common mode voltage of the input signal; a real-time signal judging circuit for real-time amplifying the difference between the input signal and the reference voltage; and a surge and noise removing circuit, for sampling and/or amplifying the output signal on the judging circuit of the real-time signal, and converting the sampling result into the digitalized output signal.