EXTENDING BEAMFORMING CAPABILITY OF A COUPLED VOLTAGE CONTROLLED OSCILLATOR (VCO) ARRAY DURING LOCAL OSCILLATOR (LO) SIGNAL GENERATION THROUGH A CIRCULAR CONFIGURATION THEREOF

• US 20140266890A1
• Filed: 03/17/2014
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Schiller, Christopher T., Kennedy, Jonathan
• Granted Patent: US 9,837,714 B2
• Time in Patent Office: Days
• US Class Current: 342/367
• CPC Class Codes: H01Q 3/42 using frequency-mixing H01Q3/2676 takes precedence

Abstract

A method includes separating phase of Local Oscillator (LO) signals generated by individual Voltage Controlled Oscillators (VCOs) of a coupled VCO array through varying voltage levels of voltage control inputs thereto. The method also includes coupling the individual VCOs of the coupled VCO array to one another in a closed, circular configuration to increase phase difference between the phase separated LO signals generated by the individual VCOs compared to a linear configuration of the coupled VCO array. Further, the method includes mixing outputs of the individual VCOs of the circular coupled VCO array with signals from antenna elements of an antenna array to introduce differential phase shifts in signal paths coupled to the antenna elements during performing beamforming with the antenna array.

Claims

1. A method comprising:

separating phase of Local Oscillator (LO) signals generated by individual Voltage Controlled Oscillators (VCOs) of a coupled VCO array through varying voltage levels of voltage control inputs thereto;

coupling the individual VCOs of the coupled VCO array to one another in a closed, circular configuration to increase phase difference between the phase separated LO signals generated by the individual VCOs compared to a linear configuration of the coupled VCO array; and

mixing outputs of the individual VCOs of the circular coupled VCO array with signals from antenna elements of an antenna array to introduce differential phase shifts in signal paths coupled to the antenna elements during performing beamforming with the antenna array.

2. The method of claim 1, further comprising:

injection locking two or more VCOs of the circular coupled VCO array to each other; and

controlling operating frequency of the circular coupled VCO array through an independent reference frequency source.

3. The method of claim 2, comprising coupling a VCO of the circular coupled VCO array to another VCO thereof through a bidirectional coupling circuit.

4. The method of claim 1, comprising providing one of:

a one-dimensional, a two-dimensional and a three-dimensional VCO array as the circular coupled VCO array.

5. The method of claim 1, further comprising combining outputs of the mixing at a combiner circuit as part of the beamforming.

6. The method of claim 1, further comprising choosing a subset of the individual VCOs of the circular coupled VCO array to generate a requisite phase difference between the LO signals generated therethrough.

7. The method of claim 3, further comprising breaking the circular coupled VCO array to form at least one linear coupled VCO sub-array therefrom based on transforming at least one bidirectional coupling circuit of the circular coupled VCO array into a corresponding at least one isolation circuit.

8. A beamforming system comprising:

a coupled VCO array comprising a plurality of individual VCOs configured to have phase of LO signals generated therethrough separated by varying voltage levels of voltage control inputs thereto, the individual VCOs of the coupled VCO array being coupled to one another in a closed, circular configuration to increase phase difference between the phase separated LO signals generated by the individual VCOs compared to a linear configuration of the coupled VCO array;

an antenna array comprising a plurality of antenna elements; and

a plurality of mixers, each of which is configured to mix an output of each individual VCO of the circular coupled VCO array with a signal from an antenna element of the antenna array to introduce differential phase shifts in signal paths coupled to the antenna elements during performing beamforming with the antenna array.

9. The beamforming system of claim 8, wherein:

two or more VCOs of the circular coupled VCO array are injection locked to each other, and

the beamforming system further comprises an independent reference frequency source to control operating frequency of the circular coupled VCO array.

10. The beamforming system of claim 9, further comprising a plurality of bidirectional coupling circuits, each of which is configured to couple a VCO of the circular coupled VCO array to another VCO thereof.

11. The beamforming system of claim 8, wherein the circular coupled VCO array is one of:

a one-dimensional, a two-dimensional and a three-dimensional VCO array.

12. The beamforming system of claim 8, further comprising a combiner circuit to combine outputs of the plurality of mixers as part of the beamforming.

13. The beamforming system of claim 8, wherein a subset of the individual VCOs of the circular coupled VCO array is chosen to generate a requisite phase difference between the LO signals generated therethrough.

14. The beamforming system of claim 10, wherein the circular coupled VCO array is broken to form at least one linear coupled VCO sub-array therefrom based on transforming at least one bidirectional coupling circuit of the circular coupled VCO array into a corresponding at least one isolation circuit.

15. A wireless communication system comprising:

a beamforming system comprising;

a coupled VCO array comprising a plurality of individual VCOs configured to have phase of LO signals generated therethrough separated by varying voltage levels of voltage control inputs thereto, the individual VCOs of the coupled VCO array being coupled to one another in a closed, circular configuration to increase phase difference between the phase separated LO signals generated by the individual VCOs compared to a linear configuration of the coupled VCO array;

an antenna array comprising a plurality of antenna elements; and

a plurality of mixers, each of which is configured to mix an output of each individual VCO of the circular coupled VCO array with a signal from an antenna element of the antenna array to introduce differential phase shifts in signal paths coupled to the antenna elements during performing beamforming with the antenna array; and

a receiver channel configured to receive a combined output of the plurality of mixers of the beamforming system.

16. The wireless communication system of claim 15, wherein:

two or more VCOs of the circular coupled VCO array of the beamforming system are injection locked to each other, and

the beamforming system further comprises an independent reference frequency source to control operating frequency of the circular coupled VCO array thereof.

17. The wireless communication system of claim 16, wherein the beamforming system further comprises a plurality of bidirectional coupling circuits, each of which is configured to couple a VCO of the circular coupled VCO array to another VCO thereof.

18. The wireless communication system of claim 15, wherein the circular coupled VCO array of the beamforming system is one of:

a one-dimensional, a two-dimensional and a three-dimensional VCO array.

19. The wireless communication system of claim 15, wherein a subset of the individual VCOs of the circular coupled VCO array of the beamforming system is chosen to generate a requisite phase difference between the LO signals generated therethrough.

20. The wireless communication system of claim 17, wherein the circular coupled VCO array of the beamforming system is broken to form at least one linear coupled VCO sub-array therefrom based on transforming at least one bidirectional coupling circuit of the circular coupled VCO array into a corresponding at least one isolation circuit.