| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a noise filter that achieves protection against noise in both modes of a common mode and a differential mode according to a transmission method of a signal flowing through a transmission line.SOLUTION: In a laminated common-mode choke coil, the thickness d of a piezoelectric body 2c sandwiched between a primary coil part 2b and a secondary coil part 2d is changed according to an applied voltage to control internal electrodes 11a and 11b by causing a voltage to be applied in a thickness direction of the piezoelectric body 2c through the control internal electrodes 11a and 11b. Accordingly, the physical distance between the primary coil part 2b and the secondary coil part 2d is controlled by a voltage applied to the piezoelectric body 2c, and the coupling degree k between the primary coil part 2b and the secondary coil part 2d is changeable by controlling the voltage applied to the piezoelectric body 2c. For this reason, both impedances of a common-mode impedance Zc and a differential-mode impedance Zd can be controlled by changing the coupling degree k according to a transmission method of a signal.</p> |
