Inductor compensating circuit

• US 20060006849A1
• Filed: 06/28/2005
• Published: 01/12/2006
• Est. Priority Date: 06/28/2004
• Status: Abandoned Application

• Current Assignee: Telecommunications Research Laboratories
• Original Assignee: Telecommunications Research Laboratories
• Inventors: Haslett, James William, Holdenried, Christopher Daniel
• Application Number:
  US11/170,719
• Publication Number:
  US 20060006849A1
• Time in Patent Office: Days
• US Class Current: 323/247
• CPC Class Codes: H03H 11/48 simulating reactances

Abstract

An inductor compensating circuit, comprising a first inductor, a second inductor, and a third inductor. A source of voltage applies an AC voltage to the first inductor. Two transistors are connected as a differential pair. A current source is connected to the source of the transistors, and the first inductor is connected between the gates of the differential pair such that the current of the differential pair is proportional to the AC voltage in the first inductor and that has a phase relationship with the AC voltage in the first inductor to achieve loss compensation in the first inductor. The second and third inductors are driven by the differential pair and coupled to the first inductor to compensate for loss in the first inductor.

Claims

1. An inductor compensating circuit, comprising:

a first inductor;

a source of voltage to apply an AC voltage to the first inductor;

transistors connected as a differential pair and having a source;

a current source connected to the source of the transistors;

a second inductor driven by the differential pair and coupled to the first inductor; and

the first inductor connected between the gates of the differential pair such that the current of the differential pair is proportional to the AC voltage in the first inductor and has a phase relationship with the AC voltage in the first inductor to achieve loss compensation in the first inductor.

2. The inductor compensating circuit of claim 1 further comprising a third inductor driven by the differential pair and coupled to the first inductor and the second inductor to compensate for loss in the first inductor.

3. The inductor compensating circuit of claim 1 wherein the current source connected to the source of the transistors is a variable current source.

4. The inductor compensating circuit of claim 3 wherein the variable current source is varied by an external circuit adapted to optimize the loss compensation.

5. The inductor compensating circuit of claim 1, wherein the first inductor is a component in a circuit selected from the group consisting of:

a filter, an LC pseudo transmission line, a resonator, and an oscillator.

6. The inductor compensating circuit of claim 1, wherein the transistors are selected from a group consisting of:

field effect transistors, bipolar junction transistors, and heterojunction bipolar transistors.

7. The inductor compensating circuit of claim 2, wherein the first inductor, the second inductor and the third inductor comprise the windings of a balun.

8. The inductor compensating circuit of claim 1, wherein the circuit further comprises a circuit stabilizing element connected to the differential pair.

9. The inductor compensating circuit of claim 8, wherein the circuit stabilizing element comprises a capacitor connected across the second inductor.

10. The inductor compensating circuit of claim 1, wherein the differential pair comprises more than one differential pair connected in parallel, where each differential pair is biased by a different bias current and each differential pair has different sized transistors.

11. A method of compensating an inductor in a circuit, the method comprising the steps of:

providing two transistors connected as a differential pair;

connecting a first inductor to be compensated between the gates of the differential pair;

connecting a second inductor and a third inductor to the differential pair and coupling the second inductor and the third inductor to the first inductor; and

driving the differential pair with a current that is proportional to the AC voltage in the first inductor and that has a phase relationship with the AC voltage in the first inductor to achieve loss compensation in the first inductor.

12. A transformer compensated circuit, comprising:

a transformer having a primary winding and a secondary winding;

a source of voltage connected to apply an AC voltage to the primary winding of the transformer;

a current source connected to drive AC current into the secondary winding of the transformer;

the current source being configured to drive an AC current into the secondary winding that is proportional to the AC voltage in the primary winding and that has a phase relationship with the AC voltage in the primary winding to achieve loss compensation in the primary winding; and

a circuit stabilizing element connected to the secondary winding.

13. The transformer compensated circuit of claim 12, wherein the circuit stabilizing element comprises a capacitor connected across the secondary winding.