Inductance variable device
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsDaisuke Watanabe, Takuo Hino
Life of this patent
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Abstract
A inductance variable device includes a first inductor, a second inductor magnetically coupled to the first inductor, a current source whose current is variable, electrically connected to the first inductor, and a current control unit which controls a current flowing from the current source to the first inductor according to a feedback signal having frequency information in a current flowing in the second inductor to vary a combined inductance of the second inductor.
Claims14
A inductance variable device comprising:
- a first inductor;
- a second inductor magnetically coupled to the first inductor;
- a current source whose current is variable, electrically connected to the first inductor;
- and
- a current control unit which controls a current flowing from the current source to the first inductor according to a feedback signal having frequency information in a current flowing in the second inductor to vary a combined inductance of the second inductor.
An IC chip comprising:
- a first inductor provided on a semiconductor substrate;
- a second inductor provided on the semiconductor substrate so as to be magnetically coupled to the first inductor;
- a current source whose current is variable, electrically connected to the first inductor;
- a frequency divider for dividing a frequency of a feedback signal having frequency information in a current flowing in the second inductor to a predetermined frequency;
- a phase detector for comparing a phase of the frequency divided signal with a phase of a reference signal having predetermined frequency information;
- and
- a charge pump for outputting a voltage to the current source according to an input from the phase detector, wherein
- the first and second inductors, the current source, the frequency divider, the phase detector, and the charge pump are constituted as a semiconductor integrated circuit, thereby the current source adjusts the current value according to an input signal from the charge pump.
A method of varying inductance in a inductance variable device having a first inductor, a second inductor provided so as to be magnetically coupled to the first inductor, and a current source whose current is variable and that is electrically connected to the first inductor, the method comprising:
- (a) applying a predetermined current from the current source to the first inductor;
- (b) dividing a frequency of a feedback signal having frequency information in a current flowing in the second inductor so as to be able to be compared with a reference signal;
- (c) comparing a phase of the signal whose frequency was divided with a phase of the reference signal and outputting a difference signal corresponding to its difference;
- and
- (d) finely adjusting a current value to be applied to the first inductor by a voltage corresponding to the difference signal, to control the current value to be applied to the first inductor by repeating the above steps (b) to (d) so that the difference between the frequency divided signal and the reference signal becomes small, thereby a combined inductance in the second inductor is set to a predetermined value.
Dependencies are inferred from the claim text.