# US 2013/0278355 A1 · Common mode filter provided with hightened removal function of common mode noise and de-emphasis function > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278355 A1 - Document ID: US20130278355A1 - Status: Published application - Kind: A1 - Application number: 13/916,953 - Filed: 2013-06-13 - Published: 2013-10-24 - Earliest claimed: 2011-11-15 - Assignees: Panasonic Corporation - Applicants: Panasonic Corporation - Inventors: Osamu SHIBATA - Web page: https://patentgrep.com/patent/US20130278355A1 ## CPC - H03H 7/0138: {Electrical filters or coupling circuits} - H03H 7/427: {Common-mode filters (H02J3/01 and H02M1/126 takes precedence)} - H04B 3/28: Reducing interference caused by currents induced in cable sheathing or armouring - H03H 7/0153: {Electrical filters; Controlling thereof} - H03H 7/06: including resistors (H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence) - H03H 7/1708: {Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path (H03H7/07 takes precedence)} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H04B: TRANSMISSION ## Abstract In a common mode filter, at least one common mode filter portion is provided for removing a common mode noise, and has a first terminal pair configured to include first and second terminals connected to first and second external terminals, respectively, and has a second terminal pair configured to include third and fourth terminals connected to third and fourth external terminals, respectively. The filter includes an inductor circuit including at least two inductors that are connected in parallel to the first terminal pair of the common mode filter portion and are connected in series to each other, and an external terminal connected to the connection point of the at least two inductors. The external terminal is for being directly or indirectly grounded. ## Claims ### Claim 1 A common mode filter comprising: at least one common mode filter portion configured to remove a common mode noise, the at least one common mode filter portion having a first terminal pair configured to include first and second terminals connected to first and second external terminals, respectively, and having a second terminal pair configured to include third and fourth terminals connected to third and fourth external terminals, respectively; an inductor circuit including at least first and second inductors that are connected in parallel to the first terminal pair of the common mode filter portion and are connected in series to each other; a fifth external terminal connected to a connection point of the first and second inductors; a first capacitor inserted between the first external terminal and the first terminal of the common mode filter portion; a second capacitor inserted between the second external terminal and the second terminal of the common mode filter portion; a first resistor inserted between the first terminal of the common mode filter portion and one end of the first inductor or between a connection point of the first and second inductors and the other end of the first inductor; and a second resistor inserted between the second terminal of the common mode filter portion and one end of the second inductor or between a connection point of the first and second inductors and the other end of the second inductor, wherein the fifth external terminal is for being directly or indirectly grounded. ### Claim 2 (depends on 1) The common mode filter as claimed in claim 1, further comprising: a third resistor connected in parallel to the first capacitor; and a fourth resistor connected in parallel to the second capacitor. ### Claim 3 A common mode filter comprising: at least one common mode filter portion configured to remove a common mode noise, the at least one common mode having a first terminal pair configured to include first and second terminals connected to first and second external terminals, respectively, and having a second terminal pair configured to include third and fourth terminals connected to third and fourth external terminals, respectively; and a filter circuit connected between the first terminal pair of the common mode filter portion and the first and second external terminals, wherein the filter circuit comprises: a first reactance circuit connected between the first terminal of the common mode filter portion and the first external terminal, the first reactance circuit being configured to include a parallel circuit of a series circuit of two resistors and a capacitor; a second reactance circuit connected between the second terminal of the common mode filter portion and the second external terminal, the second reactance circuit being configured to include a parallel circuit of a series circuit of two resistors and a capacitor; a third reactance circuit connected between a connection point of the two resistors of the first reactance circuit and a fifth external terminal, the third reactance circuit being configured to include a series circuit of a resistor and an inductor; and a fourth reactance circuit connected between a connection point of the two resistors of the second reactance circuit and the fifth external terminal, the fourth reactance circuit being configured to include a series circuit of a resistor and an inductor, wherein the fifth external terminal is for being directly or indirectly grounded. ### Claim 4 A common mode filter comprising: at least one common mode filter portion configured to removes a common mode noise, the at least one common mode filter portion having a first terminal pair configured to include first and second terminals connected to first and second external terminals, respectively, and having a second terminal pair configured to include third and fourth terminals connected to third and fourth external terminals, respectively; a filter circuit connected between the first terminal pair of the common mode filter portion and the first and second external terminals; a sixth external terminal connected to the first terminal of the common mode filter portion; and a seventh external terminal connected to the second terminal of the common mode filter portion, wherein the filter circuit comprises: a first circuit connected between the first terminal of the common mode filter portion and the first external terminal, the first circuit including a series circuit of two resistors; a second circuit connected between the second terminal of the common mode filter portion and the second external terminal, the second circuit including a series circuit of two resistors; a third reactance circuit connected between a connection point of the two resistors of the first circuit and a fifth external terminal, the third reactance circuit being configured to include a series circuit of a resistor and an inductor; and a fourth reactance circuit connected between a connection point of the two resistors of the second circuit and the fifth external terminal, the fourth reactance circuit being configured to include a series circuit of a resistor and an inductor, wherein the fifth external terminal is for being directly or indirectly grounded, wherein a first variable capacitor is to be connected between the first external terminal and the sixth external terminal, and wherein a second variable capacitor is to be connected between the second external terminal and the seventh external terminal. ### Claim 5 (depends on 4) The common mode filter as claimed in claim 4, further comprising a further common mode filter portion inserted between the filter circuit and the first and second terminals. ### Claim 6 (depends on 4) The common mode filter as claimed in claim 4, further comprising a further filter circuit inserted between the common mode filter and the third and fourth terminals.