Noise suppressing circuit

摘要

A noise suppressing circuit ( 1 ) suppresses noise emerging from an electronic apparatus ( 2 ) and propagating through conductive lines ( 3 a and 3 b). The noise suppressing circuit ( 1 ) comprises a low-band noise reducing circuit ( 10 ) and a high-band noise reducing circuit ( 80 ). The low-band noise reducing circuit ( 10 ) is connected to the electronic apparatus ( 2 ) through the conductive lines ( 3 a and 3 b). The high-band noise reducing circuit ( 80 ) is cascade-connected to the low-band noise reducing circuit ( 10 ) and connected to conductive lines ( 4 a and 4 b) of a power line ( 4 ). The high-band noise reducing circuit ( 80 ) comprises: a detection circuit for detecting common mode noise propagating through the conductive lines ( 3 a and 3 b); a phase-inverted signal generating circuit for generating a phase-inverted signal that has a phase opposite to the phase of the noise detected by the detection circuit; and an injection circuit for injecting the phase-inverted signal generated by the phase-inverted signal generating circuit into the conductive lines ( 3 a and 3 b).