A signal analysis circuit for a supplying-end module includes a first voltage divider circuit, for attenuating a coil signal of a supplying-end coil; a first amplifier circuit, for obtaining parts of the attenuated coil signal higher than a reference voltage to output a half-wave signal; a first envelope detector, for performing envelope extraction on the half-wave signal to obtain a DC signal; a second voltage divider circuit, for attenuating the half-wave signal; a second amplifier circuit, for obtaining parts of the attenuated half-wave signal higher than the DC signal to output an amplified half-wave signal; a second envelope detector, for performing envelope extraction on the amplified half-wave signal to generate an envelope signal; a coupling capacitor, for filtering out the DC component of the envelope signal; a third voltage divider circuit, for combining the AC component of the envelope signal with a DC voltage to retrieve a trigger signal.