Demodulation circuit of TWC loop line

The invention relates to a demodulation circuit of a TWC loop line. The demodulation circuit comprises: a frequency selection circuit which comprises an anti-phase unit, a frequency division unit, and a coupling unit connected with the anti-phase unit and the frequency division unit, wherein the anti-phase unit receives an input signal and carries out phase inversion to obtain an anti-phase input signal; a filter circuit which comprises two filter units, wherein the input ends of the two filter units are respectively connected with the output end of the coupling unit; a first comparison amplification circuit which comprises two comparison amplification units, wherein the input ends of the two comparison amplification units are correspondingly connected with the output ends of the two filter units respectively; and a vector summing circuit, wherein the input end of the vector summing circuit is respectively connected with the output ends of the two comparison amplification units. Compared with the prior art, t