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US 8,148,972 B2Granted
Filter circuit and method of controlling same
AssigneeNEC Corporation
InventorsTsuyoshi Tsutsumi, Eishi Matsuda
Life of this patent
Estimating the term…
Abstract
Disclosed is a filter circuit that includes means for monitoring currents flowing through positive and negative windings of a common-mode noise filter, and means for performing an adjustment based on the result of monitoring so as to equalize the current flowing positive and negative windings.
Claims4
A filter circuit comprising:
- a monitoring circuit that monitors positive winding current and negative winding current flowing respectively through a positive winding and a negative winding of a common-mode choke coil;
- and
- an adjusting circuit that a lies an adjustment based on the result of monitoring the positive winding current and the negative winding current in such a manner that balance is achieved between the positive winding current and negative winding current,
- wherein the monitoring circuit includes first and second current detecting circuits that detect current values of the positive winding current and negative winding current, respectively,
- wherein the adjusting circuit includes:
- a differential amplifier that compares the current values detected by the first and second current detecting circuits and produces a signal conforming to the comparison result;
- and
- a first current control element and/or a second current control element inserted into a path of the positive winding current and/or a path of the negative winding current of the common-mode choke coil, the first current control element and/or second current control element each receiving the signal from the differential amplifier and varying a value of current flowing through the path into which the current control element is inserted.
5 more elements
A filter circuit comprising:
- a monitoring circuit that monitors positive winding current and negative winding current flowing respectively through a positive winding and a negative winding of a common-mode choke coil;
- and
- an adjusting circuit that a lies an adjustment based on the result of monitoring the positive winding current and the negative winding current in such a manner that balance is achieved between the positive winding current and negative winding current
- wherein the monitoring circuit includes first and second voltage-drop circuits that output respective voltages conforming to the positive winding current and negative winding current respectively,
- wherein the adjusting circuit includes:
- a differential amplifier that compares a mid-point potential of the voltage across input side lines of the first and second voltage-drop circuits and a mid-point potential of the voltage across output side lines of the first and second voltage-drop circuits and produces a signal conforming to the result of comparison;
- and
- a first current control element and/or a second current control element inserted into a path of the positive winding current and/or a path of the negative winding current of the common-mode choke coil, the first current control element and/or second current control element each receiving the signal output from the differential amplifier and varying a value of current flowing through the path into which the current control element is inserted.
5 more elements
A filter circuit comprising:
- a monitoring circuit that monitors positive winding current and negative winding current flowing respectively through a positive winding and a negative winding of a common-mode choke coil;
- and
- an adjusting circuit that a lies an adjustment based on the result of monitoring the positive winding current and the negative winding current in such a manner that balance is achieved between the positive winding current and negative winding current
- wherein the monitoring circuit includes first and second current detecting circuits that detect current values of the positive winding current and negative winding current, respectively,
- wherein the adjusting circuit includes:
- a differential amplifier that compares the current values detected by the first and second current detecting circuits and produces a signal conforming to the comparison result;
- and
- a first current control element and/or a second current control element inserted into a path of the positive winding current and/or a path of the negative winding current of the common-mode choke coil, the first current control element and/or second current control element each receiving the signal from the differential amplifier and varying a value of current flowing through the path into which the current control element is inserted,
- wherein the first current control element and the second current control elements comprise transistors of mutually opposite conductivity types.
6 more elements
A filter circuit comprising:
- a monitoring circuit that monitors positive winding current and negative winding current flowing respectively through a positive winding and a negative winding of a common-mode choke coil;
- and
- an adjusting circuit that a lies an adjustment based on the result of monitoring the positive winding current and the negative winding current in such a manner that balance is achieved between the positive winding current and negative winding current
- wherein the monitoring circuit includes first and second voltage-drop circuits that output respective voltages conforming to the positive winding current and negative winding current respectively,
- wherein the adjusting circuit includes:
- a differential amplifier that compares a mid-point potential of the voltage across input side lines of the first and second voltage-drop circuits and a mid-point potential of the voltage across output side lines of the first and second voltage-drop circuits and produces a signal conforming to the result of comparison;
- and
- a first current control element and/or a second current control element inserted into a path of the positive winding current and/or a path of the negative winding current of the common-mode choke coil, the first current control element and/or second current control element each receiving the signal output from the differential amplifier and varying a value of current flowing through the path into which the current control element is inserted,
- wherein the first current control element and the second current control elements comprise transistors of mutually opposite conductivity types.
6 more elements
Dependencies are inferred from the claim text.