Tunable inductor circuit

• US 8,742,859 B2
• Filed: 12/06/2011
• Issued: 06/03/2014
• Est. Priority Date: 12/06/2011
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jin, Zhang, Liu, Li, Narathong, Chiewcham
• Primary Examiner(s): Johnson, Ryan
• Application Number:
  US13/312,177
• Publication Number:
  US 20130141177A1
• Time in Patent Office: 910 Days
• Field of Search: 331/117.FE, 331/36.L, 331/177.V, 331/117.R, 331/167, 331/177.R, 331/179, 331/181, 327/427, 336/232, 336/200
• US Class Current: 331/117.FE
• 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
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H03B 2200/0034 including a buffer amplifier
• CPC Class Codes: H03B 2201/0266 the means comprising a transistor
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/1268 switched inductors
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A tunable inductor circuit is disclosed. The tunable inductor circuit includes a first inductor. The tunable inductor circuit also includes a second inductor in parallel with the first inductor. The tunable inductor circuit also includes a switch coupled to the second inductor. A resistance of the switch is added in parallel to the first inductor based on operation of the switch.

Claims

1. A tunable inductor circuit, comprising:

a first inductor;

a second inductor that has two turns and is in parallel with the first inductor; and

a switch coupled to the second inductor, wherein a resistance of the switch is added in parallel to the first inductor based on operation of the switch, wherein the switch is located along an inner loop of the second inductor;

a capacitor in parallel with the first inductor and the second inductor, wherein the capacitor is fabricated with two non-touching metallic portions, wherein metallic fingers extend perpendicular to their respective metallic portions and parallel to other metallic fingers.

2. The tunable inductor circuit of claim 1, wherein the capacitor is a part of a capacitor bank that produces one of a plurality of possible capacitances.

3. The tunable inductor circuit of claim 2, wherein an inductance of the second inductor is included in the tunable inductor circuit when the switch is on and the resistance of the switch is added in parallel to the first inductor when the switch is on.

4. The tunable inductor circuit of claim 3, wherein the inductance of the second inductor is not included in the tunable inductor circuit when the switch is off.

5. The tunable inductor circuit of claim 4, wherein an inductance of the tunable inductor resonates with the capacitance of the capacitor to create an output signal with a target frequency.

6. The tunable inductor circuit of claim 1, wherein the switch is an n-type metal-oxide-semiconductor (NMOS) field effect transistor or a p-type metal-oxide-semiconductor (PMOS) field effect transistor.

7. The tunable inductor circuit of claim 1, wherein the tunable inductor circuit is in a voltage controlled oscillator (VCO) core, comprising:

an inductor/capacitor (LC) tank that generates a desired frequency using the tunable inductor circuit and the capacitor; and

a first n-type metal-oxide-semiconductor (NMOS) field effect transistor with a source connected to ground, a drain connected to a first VCO core output and a gate connected to a second VCO core output;

a second NMOS field effect transistor with a source connected to ground, a drain connected to the second VCO core output and a gate connected to the first VCO core output;

a first p-type metal-oxide-semiconductor (PMOS) field effect transistor with a source connected to a voltage supply, a drain connected to the first VCO core output and a gate connected to the second VCO core output; and

a second PMOS field effect transistor with a source connected to the voltage supply, a drain connected to the second VCO core output and a gate connected to the first VCO core output.

8. The tunable inductor circuit of claim 7, wherein the first VCO core output and the second VCO core output are coupled to a buffer, comprising:

a first portion, comprising;

a first capacitance connected to the second VCO core output and a gate of a third p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the third PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a first portion output;

a second capacitance connected to the second VCO core output and a gate of a third n-type metal-oxide-semiconductor (NMOS) field effect transistor;

the third NMOS field effect transistor with a source connected to ground and a drain connected to the first portion output; and

a second portion, comprising;

a third capacitance connected to the first VCO core output and a gate of a fourth p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the fourth PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a second portion output;

a fourth capacitance connected to the first VCO core output and a gate of a fourth n-type metal-oxide-semiconductor (NMOS) field effect transistor; and

the fourth NMOS field effect transistor with a source connected to ground and a drain connected to the second portion output.

9. The tunable inductor circuit of claim 1, further comprising:

a third inductor in parallel with the first inductor and the second inductor; and

a second switch connected to the third inductor, wherein a resistance of the second switch is added in parallel to the first inductor based on operation of the second switch.

10. An integrated circuit, comprising:

a first inductor;

a second inductor that has two turns and is in parallel with the first inductor; and

a switch coupled to the second inductor, wherein a resistance of the switch is added in parallel to the first inductor based on operation of the switch, wherein the switch is located along an inner loop of the second inductor;

a capacitor in parallel with the first inductor and the second inductor, wherein the capacitor is fabricated with two non-touching metallic portions, wherein metallic fingers extend perpendicular to their respective metallic portions and parallel to other metallic fingers.

11. The integrated circuit of claim 10, wherein the capacitor is a part of a capacitor bank that produces one of a plurality of possible capacitances.

12. The integrated circuit of claim 11, wherein an inductance of the second inductor is included in the integrated circuit when the switch is on and the resistance of the switch is added in parallel to the first inductor when the switch is on.

13. The integrated circuit of claim 12, wherein the inductance of the second inductor is not included in the integrated circuit when the switch is off.

14. The integrated circuit of claim 13, wherein an inductance of the integrated circuit resonates with the capacitance of the capacitor to create an output signal with a target frequency.

15. The integrated circuit of claim 10, wherein the switch is an n-type metal-oxide-semiconductor (NMOS) field effect transistor or a p-type metal-oxide-semiconductor (PMOS) field effect transistor.

16. The integrated circuit of claim 10, wherein the integrated circuit is in a voltage controlled oscillator (VCO) core, comprising:

an inductor/capacitor (LC) tank that generates a desired frequency using the integrated circuit and the capacitor; and

a first n-type metal-oxide-semiconductor (NMOS) field effect transistor with a source connected to ground, a drain connected to a first VCO core output and a gate connected to a second VCO core output;

a second NMOS field effect transistor with a source connected to ground, a drain connected to the second VCO core output and a gate connected to the first VCO core output;

a first p-type metal-oxide-semiconductor (PMOS) field effect transistor with a source connected to a voltage supply, a drain connected to the first VCO core output and a gate connected to the second VCO core output; and

a second PMOS field effect transistor with a source connected to the voltage supply, a drain connected to the second VCO core output and a gate connected to the first VCO core output.

17. The integrated circuit of claim 16, wherein the first VCO core output and the second VCO core output are coupled to a buffer, comprising:

a first portion, comprising;

a first capacitance connected to the second VCO core output and a gate of a third p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the third PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a first portion output;

a second capacitance connected to the second VCO core output and a gate of a third n-type metal-oxide-semiconductor (NMOS) field effect transistor;

the third NMOS field effect transistor with a source connected to ground and a drain connected to the first portion output; and

a second portion, comprising;

a third capacitance connected to the first VCO core output and a gate of a fourth p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the fourth PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a second portion output;

a fourth capacitance connected to the first VCO core output and a gate of a fourth n-type metal-oxide-semiconductor (NMOS) field effect transistor; and

the fourth NMOS field effect transistor with a source connected to ground and a drain connected to the second portion output.

18. A method for tuning a tunable inductor circuit, comprising:

providing a first inductor;

providing a second inductor that has two turns and is in parallel with the first inductor; and

providing a switch coupled to the second inductor, wherein a resistance of the switch is added in parallel to the first inductor based on operation of the switch, wherein the switch is located along an inner loop of the second inductor;

providing a capacitor in parallel with the first inductor and the second inductor, wherein the capacitor is fabricated with two non-touching metallic portions, wherein metallic fingers extend perpendicular to their respective metallic portions and parallel to other metallic fingers.

19. The method of claim 18, wherein the capacitor is a part of a capacitor bank that produces one of a plurality of possible capacitances.

20. The method of claim 19, further comprising operating the switch to include an inductance of the second inductor in the tunable inductor circuit when the switch is on and adding the resistance of the switch in parallel to the first inductor when the switch is on.

21. The method of claim 20, further comprising operating the switch to not include the inductance of the second inductor in the tunable inductor circuit when the switch is off.

22. The method of claim 18, wherein the switch is an n-type metal-oxide-semiconductor (NMOS) field effect transistor or a p-type metal-oxide-semiconductor (PMOS) field effect transistor.

23. The method of claim 18, wherein the tunable inductor circuit is in a voltage controlled oscillator (VCO) core, comprising:

an inductor/capacitor (LC) tank that generates a desired frequency using the tunable inductor circuit and the parallel capacitance; and

a first n-type metal-oxide-semiconductor (NMOS) field effect transistor with a source connected to ground, a drain connected to a first VCO core output and a gate connected to a second VCO core output;

a second NMOS field effect transistor with a source connected to ground, a drain connected to the second VCO core output and a gate connected to the first VCO core output;

a first p-type metal-oxide-semiconductor (PMOS) field effect transistor with a source connected to a voltage supply, a drain connected to the first VCO core output and a gate connected to the second VCO core output; and

a second PMOS field effect transistor with a source connected to the voltage supply, a drain connected to the second VCO core output and a gate connected to the first VCO core output.

24. The method of claim 23, wherein the first VCO core output and the second VCO core output are coupled to a buffer, comprising:

a first portion, comprising;

a first capacitance connected to the second VCO core output and a gate of a third p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the third PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a first portion output;

a second capacitance connected to the second VCO core output and a gate of a third n-type metal-oxide-semiconductor (NMOS) field effect transistor;

the third NMOS field effect transistor with a source connected to ground and a drain connected to the first portion output; and

a second portion, comprising;

a third capacitance connected to the first VCO core output and a gate of a fourth p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the fourth PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a second portion output;

a fourth capacitance connected to the first VCO core output and a gate of a fourth n-type metal-oxide-semiconductor (NMOS) field effect transistor; and

the fourth NMOS field effect transistor with a source connected to ground and a drain connected to the second portion output.

25. A tunable inductor circuit, comprising:

means for providing a first inductance;

means for providing a second inductance that has two loops and is in parallel with the first inductance; and

means for switching coupled to the means for providing a second inductance, wherein a resistance of the means for switching is added in parallel to the means for providing the first inductance based on operation of the means for switching, wherein the means for switching is located along an inner loop of the second inductor;

a capacitor in parallel with the first inductance and the second inductance, wherein the capacitor is fabricated with two non-touching metallic portions, wherein metallic fingers extend perpendicular to their respective metallic portions and parallel to other metallic fingers.

26. The tunable inductor circuit of claim 25, wherein the capacitor is a part of a capacitor bank that produces one of a plurality of possible capacitances.

27. The tunable inductor circuit of claim 26, further comprising means for operating the means for switching to include the second inductance in the tunable inductor circuit when the means for switching is on and adding the resistance of the means for switching in parallel to the first inductance when the means for switching is on.

28. The tunable inductor circuit of claim 27, further comprising means for operating the means for switching to not include the second inductance in the tunable inductor circuit when the means for switching is off.

29. The tunable inductor circuit of claim 25, wherein the tunable inductor circuit is in a voltage controlled oscillator (VCO) core, comprising:

an inductor/capacitor (LC) tank that generates a desired frequency using the tunable inductor circuit and the parallel capacitance; and

a first n-type metal-oxide-semiconductor (NMOS) field effect transistor with a source connected to ground, a drain connected to a first VCO core output and a gate connected to a second VCO core output;

a second NMOS field effect transistor with a source connected to ground, a drain connected to the second VCO core output and a gate connected to the first VCO core output;

a first p-type metal-oxide-semiconductor (PMOS) field effect transistor with a source connected to a voltage supply, a drain connected to the first VCO core output and a gate connected to the second VCO core output; and

a second PMOS field effect transistor with a source connected to the voltage supply, a drain connected to the second VCO core output and a gate connected to the first VCO core output.

30. The tunable inductor circuit of claim 29, wherein the first VCO core output and the second VCO core output are coupled to a buffer, comprising:

a first portion, comprising;

a first capacitance connected to the second VCO core output and a gate of a third p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the third PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a first portion output;

a second capacitance connected to the second VCO core output and a gate of a third n-type metal-oxide-semiconductor (NMOS) field effect transistor;

the third NMOS field effect transistor with a source connected to ground and a drain connected to the first portion output; and

a second portion, comprising;

a third capacitance connected to the first VCO core output and a gate of a fourth p-type metal-oxide-semiconductor (PMOS) field effect transistor;

the fourth PMOS field effect transistor with a source connected to the voltage supply and a drain connected to a second portion output;

a fourth capacitance connected to the first VCO core output and a gate of a fourth n-type metal-oxide-semiconductor (NMOS) field effect transistor; and

the fourth NMOS field effect transistor with a source connected to ground and a drain connected to the second portion output.