Overlapping uncoupled inductors for low-cost multi-frequency voltage-controlled oscillators

• US 9,543,892 B1
• Filed: 07/16/2015
• Issued: 01/10/2017
• Est. Priority Date: 07/16/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Farazian, Mohammad, Kavousian, Amirpouya, Khalili, Alireza
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US14/801,535
• Publication Number:
  US 20170019066A1
• Time in Patent Office: 544 Days
• Field of Search: 331/36.L, 331/46, 331/117.FE, 331/117.R, 331/167, 331/181, 336/220, 336/225, 336/232
• US Class Current: 1/1
• CPC Class Codes: H03B 5/08 with frequency-determining element comprising lumped inductance and capacitance
• CPC Class Codes: H03B 5/12 active element in amplifier being semiconductor device H03B5/14 takes precedence
• CPC Class Codes: H03B 5/1206 using multiple transistors for amplification
• CPC Class Codes: H03B 5/1256 the means comprising a variable inductance

Abstract

Certain aspects of the present disclosure provide techniques and apparatus for generating multiple oscillating signals. One example circuit generally includes a first voltage-controlled oscillator (VCO) having a first inductor and a second VCO having a second inductor in parallel with a third inductor, wherein the second and third inductors are disposed inside a loop of the first inductor and may behave as a magnetic dipole. The loop of the first inductor may be symmetrical, and a combined geometry of loops of the second and third inductors may be symmetrical. The coupling coefficient (k) between the first inductor and a combination of the second and third inductors may be small (e.g., k<0.01), due to the symmetrical geometry of the circuit layout. With a smaller k, the first and second VCOs'"'"' inductors may be placed closer to one another, thereby reducing an area consumed by the two VCOs.

Claims

1. A circuit for generating multiple oscillating signals, comprising:

a first voltage-controlled oscillator (VCO) having a first inductor;

a second inductor and a third inductor disposed inside a loop of the first inductor; and

a second VCO having the second inductor connected in parallel with the third inductor, wherein a first output of the second VCO is coupled to a first terminal of the second and third inductors, and wherein a second output of the second VCO is coupled to a second terminal of the second and third inductors.

2. The circuit of claim 1, wherein the second inductor has a same geometry as the third inductor.

3. The circuit of claim 2, wherein the second and third inductors are configured to behave as a magnetic dipole during operation of the second VCO.

4. The circuit of claim 1, wherein:

the loop of the first inductor is symmetrical; and

a combined geometry of a loop of the second inductor and of a loop of the third inductor is symmetrical.

5. The circuit of claim 4, wherein an axis of symmetry for the first inductor is aligned with an axis of symmetry for the combined geometry.

6. The circuit of claim 5, wherein the axis of symmetry for the combined geometry is located at one or more junctions between the second and third inductors.

7. The circuit of claim 6, wherein the second VCO further comprises a capacitor located at at least one of the junctions and configured to couple an end of the second inductor to an end of the third inductor.

8. The circuit of claim 5, wherein the axis of symmetry for the combined geometry divides the loop of the second inductor into two equal halves and divides the loop of the third inductor into two equal halves.

9. The circuit of claim 1, wherein a coupling coefficient between the first inductor and a combination of the second and third inductors is less than 0.01.

10. The circuit of claim 1, wherein the second and third inductors are configured to provide an electromagnetic shield for the first inductor.

11. The circuit of claim 1, wherein the second VCO, including the second and third inductors, is disposed inside the loop of the first inductor.

12. The circuit of claim 1, wherein a frequency band of the first VCO at least partially overlaps with a frequency band of the second VCO.

13. The circuit of claim 1, wherein the first, second, and third inductors are located in a same plane.

14. The circuit of claim 1, wherein the first and second inductors are configured to be concurrently active.

15. A method for generating multiple oscillating signals, comprising:

generating a first oscillating signal using a first voltage-controlled oscillator (VCO) having a first inductor; and

generating a second oscillating signal using a second VCO having a second inductor in parallel with a third inductor, wherein the second and third inductors are disposed inside a loop of the first inductor, wherein the first inductor is uncoupled between a combination of the second and third inductors.

16. The method of claim 15, wherein the second inductor has a same geometry as the third inductor.

17. The method of claim 16, wherein generating the second oscillating signal using the second VCO comprises the second and third inductors behaving as a magnetic dipole.

18. The method of claim 15, wherein:

the loop of the first inductor is symmetrical; and

a combined geometry of a loop of the second inductor and of a loop of the third inductor is symmetrical.

19. The method of claim 18, wherein an axis of symmetry for the first inductor is aligned with an axis of symmetry for the combined geometry.

20. The method of claim 19, wherein the axis of symmetry for the combined geometry is located at a junction between the second and third inductors.

21. The method of claim 20, further comprising coupling an end of the second inductor with an end of the third inductor using at least one capacitor located at the junction.

22. The method of claim 15, wherein a coupling coefficient between the first inductor and a combination of the second and third inductors is less than 0.01.

23. The method of claim 15, further comprising electromagnetically shielding the first inductor with the second and third inductors.

24. The method of claim 15, wherein the second VCO, including the second and third inductors, is disposed inside the loop of the first inductor.

25. The method of claim 15, wherein a frequency band of the first VCO does not overlap with a frequency band of the second VCO.

26. The method of claim 15, wherein the first, second, and third inductors are located in a same plane.

27. The method of claim 15, wherein generating the first oscillating signal occurs concurrently with generating the second oscillating signal.

28. An apparatus for generating multiple oscillating signals, comprising:

means for generating a first oscillating signal using a first inductor; and

means for generating a second oscillating signal using a second inductor in parallel with a third inductor, wherein the second and third inductors are disposed inside a loop of the first inductor, wherein the second and third inductors are configured to provide an electromagnetic shield for the first inductor.

29. The apparatus of claim 28, further comprising means for capacitively coupling at least one end of the second inductor with at least one end of the third inductor.

30. The apparatus of claim 28, wherein the means for generating the first oscillating signal and the means for generating the second oscillating signal are concurrently active.

31. The apparatus of claim 28, wherein a first output terminal of the means for generating a second oscillating signal is coupled to a first terminal of the second and third inductors, and wherein a second output terminal of the means for generating a second oscillating signal is coupled to a second terminal of the second and third inductors.