FERRITE RESONATORS USING MAGNETIC BIASING AND SPIN PRECESSION

Abstract

A low loss unidirectional conductive sheet using magnetic field biasing and electron spin precession for coupling RF power to ferrite resonators, comprising the step of placing a plurality of ferrite resonators in a bias magnetic field to excite the electron spins of the materials of said ferrite resonators into precession.

Claims

1. A method for generating low phase noise microwave oscillations by lossless resonators mutually coupled in a magnetic bias field, and providing the feedback energy and phase shift function necessary to maintain oscillation

2. A method to increase efficiency in tuning ferromagnetic resonators, comprising: using an array field of mutually coupled basis resonator cells to reduce the working magnetic gap length that biases the resonator.

3. An energy efficient method for distributing power with microwave oscillations, comprising coupling a plurality of ferromagnetic resonators at a frequency determined by resonant material in a biasing magnetic field.

4. A low loss unidirectional conductive sheet using magnetic field biasing and electron spin precession for coupling RF power to ferrite resonators, comprising the step of placing a plurality of ferrite resonators in a bias magnetic field to excite the electron spins of the materials of said ferrite resonators into precession.

5. The unidirectional conductive sheet of claim 4, wherein said bias magnetic field is a static bias magnetic field that induces electron spin precession resonance in said ferrite resonators.

6. The unidirectional conductive sheet of claim 5, wherein said static bias magnetic field generates a precessional rotational cycle linearly proportional to the applied magnetic field.

7. The unidirectional conductive sheet of claim 6, further including a time-varying electromagnetic field orthogonal to said bias magnetic field and having the same frequency as the electron spin precession, wherein said time-varying magnetic field interacts with electron precession due to magnetic coupling.

8. The unidirectional conductive sheet of claim 7, wherein in the absence of an external RF field at the frequency of the precessional rate, as long as said bias magnetic field is present, electron spin precession in said ferrite resonators continues without energy loss.

9. The unidirectional conductive sheet of claim 7, wherein changes in said bias magnetic field intensity causes changes in the frequency of the electron spin precession proportional to the changes in bias magnetic field intensity.

10. The unidirectional conductive sheet of claim 7, wherein energy transferred to and from said time-varying magnetic field.

11. The unidirectional conductive sheet of claim 10, wherein if there is no loss in conductors generating the time-varying magnetic field, then the time-varying magnetic field continues undiminished until lost through radiation.

12. The unidirectional conductive sheet of claim 11, wherein energy from said time-varying magnetic field is translated to an application.

13. The unidirectional conductive sheet of claim 12, wherein said time-varying magnetic field is coupled to said ferrite resonators through an electrical signal transmission device selected from the group consisting of current loops, transmission lines, and wave guides.

14. A magnetic biased low loss unidirectional conductive sheet that couples RF power to a ferrite resonator, comprising: a first coupling puck having a disc body with generally planar top and bottoms sides; an array of spaced apart parallel conductor strips separated by dielectric and disposed on said top side of said disc body to form a wide pattern; and a ferrite resonator disposed on said top side of said first coupling puck.

15. The conductive sheet of claim 14, wherein said array of parallel conductor strips is wider than said ferrite resonator and long enough to eliminate end effects in relation to said ferrite resonator.

16. The conductive sheet of claim 15, wherein said conductor strips extend from their ends at each side of said array into an expanded region of thin conductor material disposed over a portion of the top surface of said top side of said disc body.

17. The conductive sheet of claim 16, wherein said conductor strips and said expanded conductor regions are each fabricated from graphene.

18. The conductive sheet of claim 14, wherein said coupling puck is a planar circular disc body truncated along first and second parallel chords equidistant from and parallel to a first centerline and bisected by a second centerline perpendicular to said first centerline.

19. The conductive sheet of claim 14, wherein said resonator is spaced apart from said top side of said coupling puck.

20. The conductive sheet of claim 19, wherein said resonator is disposed on a cupped dielectric pedestal.

21. The conductive sheet of claim 20, wherein said conductive sheet further includes a second coupling puck disposed under said first coupling puck, said second coupling puck having a disc body with generally planar top and bottoms sides and an array of spaced apart parallel conductor strips separated by dielectric and disposed on said top side of said disc body to form a wide pattern of conductor strips orthogonal to said conductor strips of said array on said first coupling puck.

22. The conductive sheet of claim 14, wherein said conductive sheet further includes a second coupling puck disposed under said first coupling puck, said second coupling puck having a disc body with generally planar top and bottoms sides and an array of spaced apart parallel conductor strips separated by dielectric and disposed on said top side of said disc body to form a wide pattern of conductor strips orthogonal to said conductor strips of said array on said first coupling puck.

23. The conductive sheet of claim 22, wherein said first and second coupling pucks are disposed between first and second magnetic biasing plates.

24. The conductive sheet of claim 22, wherein said ferrite resonator is a nanoscale YIG sphere.

25. The conductive sheet of claim 14, wherein said ferrite resonator is a nanoscale YIG sphere.

26. The conductive sheet of claim 14, including an array of nanoscale YIG spheres disposed on a plurality of said coupling pucks and spaced to optimize magnetic coupling between said nanoscales YIG spheres at a frequency determined by the bias magnetic field intensity.

27. The conductive sheet of claim 25, wherein said array of YIG spheres are coupled together by adjacent sphere-to-sphere RF magnetic fields.

28. The conductive sheet of claim 26, wherein said YIG spheres are confined within a region small in relation to wavelength in air, such that all YIG spheres in the array may be excited into a simultaneous resonance at the same frequency as determined by the DC magnetic field.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will be better understood and its various objects and advantages will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

[0017] FIG. 1 is a highly schematic top plan view of a the coupling puck used in the magnetic biased high Q resonator of the present invention;

[0018] FIG. 2 is an upper perspective view showing paired coupling pucks and a ferrite resonator disposed above the upper puck;

[0019] FIG. 3 is a side view in elevation thereof showing the magnetic biasing plates above and below the resonator assembly;

[0020] FIG. 4 is an upper perspective view showing a puck assembly incorporated into and electronically connected to differential amplifiers ICs to produce a differential oscillator when in a magnetic biasing circuit;

[0021] FIG. 5 is a partial detailed cross sectional view showing the layers of the paired nanoscale coupling pucks and a plurality of ferrite nano-spheres disposed atop the upper puck below a single magnetic biasing plate (the lower plate removed for clarity); and

[0022] FIG. 6 is a highly schematic top plan view showing how multiple YIG nano-spheres are coupled through a matrix of AC magnetic fields to form a single quasi 2-dimensional Q multiplying YIG resonator.

BEST MODE FOR CARRYING OUT THE INVENTION

[0023] Referring to FIGS. 1 through 6, wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved magnetic biased low loss unidirectional conductive sheet device that couples RF power to a ferrite resonator. In a preferred embodiment, the primary component is the coupling puck 10. The coupling comprises an array of parallel thin conductor strips 12 spaced apart and separated by dielectric 14 to form a very wide pattern 16 on the top side 18 of the disc body 20 that is much wider than the resonator material and long enough to eliminate end effects in relation to the resonator. The thin conductor strips extend from each side of the array into an expanded region of thin conductor material 15 disposed over a portion of the top surface 18 of the disc body. The recently developed Graphene conductors may be ideal for use as the conductor strips and expanded conductor regions.

[0024] The coupling puck 10 is configured as a planar circular disc body 18 cut along first and second parallel chords 22, 24, each equidistant from and parallel to a first centerline 26 and each bisected by a second centerline 28 perpendicular to the first centerline 26. The width dimension X and its radius of curvature R at its ends are defined by the scale of the application. This puck can be close to the resonator 30 (in this instance a single spherical YIG resonator) or at some distance depending on the response required, thus a cupped dielectric support, pin, or pedestal 32 of a variable but specific height and size is provided.

[0025] Units may be constructed using macro-sized coupling pucks, as shown in FIGS. 2-4. A first puck 10 is affixed such that its conductor strips 12 are at a right angle in relation to the conductor strips (not shown in FIGS. 2-3) on a second puck 40 to reduce parasitic coupling between the pucks. The pucks are disposed between first and second magnetic biasing plates 42, 44. Testing of the arrangement has demonstrated the operability of the concept with one device, and the mathematics allows extension to the nano resonators.

[0026] In an embodiment, a nanoscale YIG sphere, or a sphere formed from other similar material, is spaced such that the magnetic coupling between nano sites is optimal for coupling electromagnetic energy among the sites at a frequency determined by the magnetic field intensity. The first component considered is an oscillator to excite an array.

[0027] To better understand the functional operation, we consider first what happens in the case of thermal noise. Thermal noise sources modulate the oscillator's frequency and phase such that a mean square frequency deviation, Δω.sup.2 is created. The frequency deviation modulates the carrier, and the value of the mean square frequency deviation is calculated from the expression:

Δω.sup.2=ω0.sup.2kTnB/4Qr.sup.2Pout   (1)

[0028] Thermal noise dominates phase noise far from the carrier (before reaching the background noise floor). However, up-converted 1/f noise dominates phase noise at frequencies close to the carrier. The up-converted mean squared frequency deviation of a transistor oscillator is given by

Δω.sup.2=[ω.sub.o(∂Cd/∂V0/2QrGr].sup.2Sv0(ω)   (2)

[0029] Equations (1) and (2) above show that both the thermal and up-converted 1/f phase noise are dependent on 1/Q.sup.2. This relationship makes the Q factor of the YIG resonator a primary controlling factor in reducing phase noise and time jitter of a YIG-tuned oscillator. The loaded Q factor of a single sphere YIG resonator is between 600 and 9000, depending on geometric and materials factors. Q multiplication can take pace by placing multiple YIG spheres within the resonance of the oscillator. An array of YIG spheres (shown in FIGS. 5-6) are coupled together by adjacent sphere-to-sphere RF magnetic fields. By keeping all of the spheres within a space that is small compared to a wavelength in air, it is possible to excite all spheres in the array into a simultaneous resonance at the same frequency, which is determined by the DC magnetic field. By “locking” all of the spheres together at a single resonant frequency, it is possible to achieve an effect similar to adding sections to a large multi-section filter. Just as in the case of the multi-section filter, the additional YIG spheres sharpen the filter's response, reducing its bandwidth.

[0030] FIG. 4 shows the invention implemented as an oscillator 50 that includes a lower pair of coupling pucks 52 connected to a first differential amplifier 54, and a single upper puck 56 connected to a second differential amplifier 58, the single upper puck providing a series return for the lower puck pair such that its magnetic field adds to the total magnetic field driving a YIG sphere. The YIG sphere is not shown in this view for purposes of clarity, but in this configuration it is disposed in the region between the lower pair of coupling pucks and the upper puck. A conductive spacer 60 connects current between the lower and upper pucks so that current can flow around the YIG sphere. Other nonconductive spacers (not shown) can be provided for structural support for the pucks. It will be appreciated that combining puck layers having different phases can be employed for circuit development.

[0031] FIG. 5 is a partial detailed cross sectional view showing paired coupling pucks 70 including a first puck 72 having an array of spaced conductor strips 74 disposed on an upper side, and a second puck 76 having an array of conductor strips 78 generally normal to the conductor strips on the first puck. In this instance, however, rather than a single ferrite or YIG sphere, there are numerous spheres 80 disposed atop the upper puck so as to form an array, which might be configured along the lines of the array 82 shown in FIG. 6.

[0032] FIG. 6 is a highly schematic view showing how such an array 82 of multiple YIG spheres 84 may be coupled via a matrix of AC magnetic fields to form a single Q-multiplying YIG resonator. This resonator is coupled to the rest of the circuit by a pair of coupling pucks 90, 92 that must be physically associated with only one of the YIG spheres 94. The array of spheres can be associated with a conventional integrated circuit (IC) in an adjacent layer to couple individual nano-YIGs to various functions on the IC. In this way, power to energize and the distribution of low jitter clocking cycles can be applied to a computer, DAC, ADC, memory, and higher functions utilizing both digital and analog circuits. This results in the ability to build much larger ICs and conserve power at the same time.

[0033] The overall Q of this structure is equal to the YIG filter's center frequency divided by its 3 dB bandwidth. Therefore, the addition of multiple coupled YIG spheres that reduce bandwidth will also raise Q. With 6 to 87 coupled spheres it is possible to raise the overall filter Q into the 6,000 to 15,000 range. Such an order-of-magnitude increase in Q reduces phase noise in both the thermal and 1/f regions by 20 dB, and it reduces the cycle-to-cycle time jitter by approximately a factor of 10. With this kind of improvement, it is possible to realize an overall jitter performance in the sub-1 fs range up to oscillator center frequencies of 23 GHz.

[0034] The above disclosure is sufficient to enable one of ordinary skill in the art to practice the invention, and provides the best mode of practicing the invention presently contemplated by the inventors. While there is provided herein a full and complete disclosure of the preferred embodiments of this invention, the invention is not limited to the exact construction, dimensional relationships, and operation shown and described. Various modifications, alternative constructions, changes and equivalents will occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Therefore, the above description and illustrations should not be construed as limiting the scope of the invention, which is defined by the appended claims.