Low noise oscillator

• US 8,339,210 B2
• Filed: 05/11/2011
• Issued: 12/25/2012
• Est. Priority Date: 05/11/2011
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nylen, Tomas
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US13/130,670
• Publication Number:
  US 20120286879A1
• Time in Patent Office: 594 Days
• Field of Search: 331/34, 331/117.FE, 331/117.R, 331/167
• US Class Current: 331/117.R
• CPC Class Codes: H03B 5/1852 the semiconductor device being a field-effect device

Abstract

An oscillator for use in generating a signal having a desired frequency includes a first inductor element being electrically coupled from one end of a first capacitive element to a first voltage connection point, a second inductor element being electrically coupled from one end of a second capacitive element to a second voltage connection point, a third inductor element being electrically coupled from another end of the first capacitive element to the first voltage connection point, a fourth inductor element being electrically coupled from another end of the second capacitive element to the second voltage connection point. The first, second, third, and fourth inductor elements being configured such that a first conductive trace loop formed by the first and third inductor elements is interleaved with a second conductive trace loop formed by the second and fourth inductor elements such that said conductive trace loops are configured to operate in substantially a same magnetic field. A first drive circuit is electrically coupled to the first and second inductor elements forming a first resonance circuit with the first and second capacitive elements and a second drive circuit is electrically coupled to the third and fourth inductor elements forming a second resonance circuit with the first and second capacitive elements, such that the first and second drive circuits are mutually configured to establish and maintain a unified oscillation in the first and second resonance circuits at the desired frequency.

Claims

1. An oscillator for use in generating a signal having a desired frequency in a frequency synthesizer, comprising:

a first inductor element being electrically coupled from one end of a first capacitive element to a first voltage connection point;

a second inductor element being electrically coupled from one end of a second capacitive element to a second voltage connection point;

a third inductor element being electrically coupled from another end of the first capacitive element to the first voltage connection point;

a fourth inductor element being electrically coupled from another end of the second capacitive element to the second voltage connection point;

said first, second, third, and fourth inductor elements being configured such that a first conductive trace loop formed by the first and third inductor elements is interleaved with a second conductive trace loop formed by the second and fourth inductor elements such that said conductive trace loops are configured to operate in substantially a same magnetic field,

wherein a first drive circuit is electrically coupled to the first and second inductor elements between the first and second capacitive elements such that the first and second inductor elements connect the first drive circuit to the first and second capacitive elements, respectively, so as to form a first resonance circuit with the first and second capacitive elements and a second drive circuit is electrically coupled to the third and fourth inductor elements between the first and second capacitive elements such that the third and fourth inductor elements connect the second drive circuit to the first and second capacitive elements, respectively, so as to form a second resonance circuit with the first and second capacitive elements, such that the first and second drive circuits are mutually configured to establish and maintain a unified oscillation in the first and second resonance circuits at the desired frequency.

2. An oscillator according to claim 1, wherein

the first drive circuit comprise a first transistor having first base and first collector terminals, the first transistor being configured such that the first collector terminal is electrically coupled to the second inductor element and the first base terminal is electrically coupled to the first inductor element, and a second transistor having second base and second collector terminals, the second transistor being configured such that the second collector terminal is electrically coupled to the first inductor element and the second base terminal is electrically coupled to the second inductor element;

and

the second drive circuit comprises a third transistor having third base and third collector terminals, the third transistor being configured such that the third collector terminal is electrically coupled to the fourth inductor element and the third base terminal is electrically coupled to the third inductor element, and a fourth transistor having fourth base and fourth collector terminals, the fourth transistor being configured such that the fourth collector terminal is electrically coupled to the third inductor element and the fourth base terminal is electrically coupled to the fourth inductor element.

3. An oscillator according to claim 1, further comprising:

a first inductor element interconnect configured to provide an electrical connection across the first and second conductive trace loops formed by the first, second, third, and fourth inductor elements such that undesired oscillation is suppressed in the oscillator.

4. An oscillator according to claim 3, wherein the first inductor element interconnect is configured to provide an electrical connection between the first voltage connection point on the first conductive trace loop formed by the first and third inductor elements and the second voltage connection point on the second conductive trace loop formed by the second and fourth inductor elements.

5. An oscillator according to claim 4, further comprising:

a second and a third inductor element interconnect configured to provide electrical connections across the first and second conductive trace loops formed by the inductor elements such that undesired oscillation is suppressed in the oscillator.

6. An oscillator according to claim 5, wherein the second inductor element interconnect is configured to provide an electrical connection between a first point on the second inductor element being substantially electrically equivalent to the first collector terminal of the first transistor, and a second point on the third inductor element being substantially electrically equivalent to the fourth collector terminal of the fourth transistor;

and

the third inductor element interconnect is configured to provide an electrical connection between a first point on the first inductor element being substantially electrically equivalent to the second collector terminal of the second transistor, and a second point on the fourth inductor element being substantially electrically equivalent to the third collector terminal of the third transistor.

7. An oscillator according to claim 6, further comprising:

at least fifth, sixth, seventh, and eighth inductor elements connected to the first, second, third and fourth inductor elements such that the inductance of the oscillator is reduced.

8. An oscillator according to claim 7, wherein the fifth inductor element is connected to the first inductor element and the first voltage connection point to form a first partial outer conductive trace loop, said first partial outer conductive trace loop being coupled in parallel with a part of the first inductor element;

the sixth inductor element is connected to the second inductor element and the second voltage connection point to form a second partial outer conductive trace loop, said second partial outer conductive trace loop being coupled in parallel with a part of the second inductor element;

the seventh inductor element is connected to the third inductor element and the first voltage connection point to form a third partial outer conductive trace loop, said third partial outer conductive trace loop being coupled in parallel with a part of the third inductor element; and

the eighth inductor element is connected to the fourth inductor element and the second voltage connection point to form a fourth partial outer conductive trace loop, said fourth partial outer conductive trace loop being coupled in parallel with a part of the fourth inductor element.

9. An oscillator according to claim 8, further comprising:

at least a third drive circuit and a fourth drive circuit, at least a third capacitive element and a fourth capacitive element, and at least fifth, sixth, seventh and eight inductor elements being configured to form at least a third resonance circuit and a fourth resonance circuit and being configured to be electrically coupled to the first and second drive circuits, the first and second capacitive elements, and the first, second, third and fourth inductor elements, such that the first and second drive circuits and the at least third and fourth drive circuits are mutually configured to establish and maintain a unified oscillation in the first and second, and at least third and fourth resonance circuits at the desired frequency.

10. An oscillator according to claim 9, further comprising:

a fourth inductor element interconnect, wherein the fourth inductor element interconnect and the first inductor element interconnect are configured to provide an electrical connection across the conductive trace loops formed by the inductor elements such that undesired oscillation is suppressed in the oscillator.

11. An oscillator according to claim 10, further comprising:

a fifth inductor element interconnect and sixth inductor element interconnect, wherein the fifth and sixth inductor element interconnects and the second and third inductor element interconnects are configured to provide electrical connections across the conductive trace loops formed by the inductor elements such that undesired oscillation is suppressed in the oscillator.

12. An oscillator according to claim 2, wherein the transistors are NPN-transistors or MOS-transistors, and the capacitive elements comprise at least one capacitor which is digitally programmable and/or tunable, said at least one capacitor being MIM-capacitors.

13. An oscillator according to claim 1, wherein the oscillator is formed as an integrated circuit [IC] and is integrated on a single die.

14. A frequency synthesizer comprising:

a phase-locked loop [PLL] for generating frequencies, and

an oscillator coupled to the PLL, comprising;

a first inductor element being electrically coupled from one end of a first capacitive element to a first voltage connection point;

a second inductor element being electrically coupled from one end of a second capacitive element to a second voltage connection point;

a third inductor element being electrically coupled from another end of the first capacitive element to the first voltage connection point;

a fourth inductor element being electrically coupled from another end of the second capacitive element to the second voltage connection point;

said first, second, third, and fourth inductor elements being configured such that a first conductive trace loop formed by the first and third inductor elements is interleaved with a second conductive trace loop formed by the second and fourth inductor elements such that said conductive trace loops are configured to operate in substantially a same magnetic field,

wherein a first drive circuit is electrically coupled to the first and second inductor elements between the first and second capacitive elements such that the first and second inductor elements connect the first drive circuit to the first and second capacitive elements, respectively, so as to form a first resonance circuit with the first and second capacitive elements and a second drive circuit is electrically coupled to the third and fourth inductor elements between the first and second capacitive elements such that the third and fourth inductor elements connect the second drive circuit to the first and second capacitive elements, respectively, so as to form a second resonance circuit with the first and second capacitive elements, such that the first and second drive circuits are mutually configured to establish and maintain a unified oscillation in the first and second resonance circuits at the desired frequency.

15. A frequency synthesizer according to claim 14, wherein the PLL and the oscillator are integrated on the same die so as to form an integrated, single chip frequency synthesizer.

16. Apparatus for use in a telecommunications network comprising:

an oscillator, comprising;

a first inductor element being electrically coupled from one end of a first capacitive element to a first voltage connection point;

a second inductor element being electrically coupled from one end of a second capacitive element to a second voltage connection point;

a third inductor element being electrically coupled from another end of the first capacitive element to the first voltage connection point;

a fourth inductor element being electrically coupled from another end of the second capacitive element to the second voltage connection point;

said first, second, third, and fourth inductor elements being configured such that a first conductive trace loop formed by the first and third inductor elements is interleaved with a second conductive trace loop formed by the second and fourth inductor elements such that said conductive trace loops are configured to operate in substantially a same magnetic field,

wherein a first drive circuit is electrically coupled to the first and second inductor elements between the first and second capacitive elements such that the first and second inductor elements connect the first drive circuit to the first and second capacitive elements, respectively, so as to form a first resonance circuit with the first and second capacitive elements and a second drive circuit is electrically coupled to the third and fourth inductor elements between the first and second capacitive elements such that the third and fourth inductor elements connect the second drive circuit to the first and second capacitive elements, respectively, so as to form a second resonance circuit with the first and second capacitive elements, such that the first and second drive circuits are mutually configured to establish and maintain a unified oscillation in the first and second resonance circuits at the desired frequency.

17. An apparatus according to claim 16, wherein the apparatus is a mobile radio base station.

18. An apparatus according to claim 16, further comprising:

a phase-locked loop [PLL] for generating frequencies coupled to the oscillator.