Variable inductor

• US 20070052512A1
• Filed: 08/31/2006
• Published: 03/08/2007
• Est. Priority Date: 09/08/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Heung-bae, Lee, Dong-hyun, Jeon, Sang-yoon, Jung, Sung-jae
• Granted Patent: US 8,054,153 B2
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 2017/0046 with a conductive path having a bridge
• CPC Class Codes: H01F 2021/125 Printed variable inductor with taps, e.g. for VCO
• CPC Class Codes: H01F 21/12 discontinuously variable, e.g. tapped

Abstract

A variable inductor is provided, which includes a first lead having both ends to receive a pair of difference signals, a second lead having both ends to receive a pair of the difference signals, and a switch selectively supplying a pair of the difference signals to the second lead by turning on/off according to a control signal. Accordingly, a variable inductor can be implemented that is compact and maximizes the variation rate of inductance.

Claims

1. A variable inductor, comprising:

a first lead which receives a pair of difference signals at a first end and a second end of the first lead, respectively;

a second lead which receives the pair of difference signals at a first end and a second end of the second lead, respectively; and

a switch which selectively supplies the pair of difference signals to the second lead by turning on or off in response to a control signal.

2. The variable inductor of claim 1, wherein a first magnetic flux generated by a first electric current flowing in the first lead in a first direction from the pair of difference signals and a second magnetic flux generated by a second electric current flowing in the second lead in a second direction from the pair of the difference signals, and the first and second magnetic fluzes counteract each other.

3. The variable inductor of claim 1, wherein the first direction of the first electric current flowing in the first lead is counterclockwise and the second direction of the second electric current flowing in the second lead is clockwise.

4. The variable inductor of claim 1, wherein the first lead has a spiral shape.

5. The variable inductor of claim 4, wherein the spiral shape of the first lead is a double spiral shape.

6. The variable inductor of claim 1, wherein the first lead comprises:

a first spiral lead receiving a first difference signal, which is one of the pair of difference signals, at one end of the first spiral lead, said first spiral lead having a radius which gradually decreases in a spiral shape relative to a virtual center; and

a second spiral lead, which is connected to another end of the first spiral lead at one end of the second spiral lead, wherein a spiral shape of the second spiral lead gradually increases in radius relative to the virtual center, and another end of the second spiral lead receives a second difference signal having a phase difference of 180°

relative to the first difference signal which is supplied to the first spiral lead.

7. The variable inductor of claim 6, wherein the first spiral lead and the second spiral lead are symmetrical with respect to a virtual line that passes through the virtual center.

8. The variable inductor of claim 7, wherein the first spiral lead and the second spiral lead overlap each other on the virtual line that passes through the virtual center such that overlapping parts of the first spiral lead and the second spiral lead are disposed at a distance from each other.

9. The variable inductor of claim 7, wherein the first spiral lead and the second spiral lead are on an identical plane except the overlapping parts of the first spiral lead and the second spiral lead which overlap on the virtual line.

10. The variable inductor of claim 1, wherein the second lead is formed on the identical plane in a loop shape relative to a virtual center, with the first end of the second lead receiving the first difference signal and the second end of the second lead receiving the second difference signal.

11. The variable inductor of claim 1, wherein the switch comprises:

a first transistor including a source terminal, a drain terminal, and a gate terminal, wherein the source terminal of the first transistor is connected to the first end of the first lead, the drain terminal of the first transistor is connected to the first end of the second lead, and the gate terminal of the first transistor receives the control signal; and

a second transistor including a source terminal, a drain terminal, and a gate terminal, wherein the source terminal of the second transistor is connected to the second end of the first lead, the drain terminal of the second transistor is connected to the second end of the second lead, and the gate terminal of the second transistor is common-connected to the gate terminal of the first transistor to receive the control signal together.

12. The variable inductor of claim 11, wherein the first transistor and the second transistor are turned on to supply the pair of difference signals to the first end and the second end of the second lead if the control signal is at a high level, and

the first transistor and the second transistor are turned off and do not supply the pair of difference signals to the second lead if the control signal is at a low level.

13. The variable inductor of claim 1, wherein the pair of difference signals are applied to the first lead and the second lead such that the first lead and second lead are positively mutually coupled.

14. The variable inductor of claim 13, wherein a direction of current flow in the first lead and the second lead is identical such that magnetic flux generated by current flow in the first lead is increased by magnetic flux generated by current flow in the second lead.