Inductance device with similar 8-shaped structure

Abstract

The invention provides an inductance device with a similar 8-shaped structure, which comprises a resonant inductor forming a first loop, a load inductor forming a second loop and a current amplifying circuit coupled between the resonant inductor and the load inductor, and is characterized in that a first current in the first loop is amplified by the current amplifying circuit to form a second current in the second loop; the direction of the first current is opposite to the direction of the second current, and the ratio of the second current to the first current is equal to the ratio of the inductance value of the load inductor to the inductance value of the resonant inductor. In this way, the magnetic flux of the first loop and the magnetic flux of the second loop are equal in intensity and opposite in direction, and therefore the magnetic flux and the magnetic flux offset each other.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and more particularly to an inductor device with a quasi-figure-8 structure. Background Art

[0002] Inductive components such as inductors and transformers participate in various functions such as resonance, matching, conversion, and load in the circuit. They are in a planar spiral structure in the chip and occupy a large area. Compared with other parts in the circuit, they are easy to radiate electromagnetic interference and are easily affected by other electromagnetic interference. In order to avoid radiating electromagnetic interference as much as possible, it is currently more common to use an 8-shaped structure to realize inductance, in which the two spiral windings that make up the 8-shaped structure have magnetic fluxes with opposite directions and equal strengths, so it can be considered that the electromagnetic interference in the horizontal direction is automatically offset. However, in practical applications, the 8-shaped structure inductor device occupies a large circuit area, and it is not cost-effective to use this structure under the condition of limited circuit area. One improvement is to wind two turns of coils (or more turns of coils) to form a double (N) 8-shaped structure, but due to the presence of more jumper overlapping parasitics, it is not possible to achieve its optimal performance at higher frequencies. For example, the Chinese invention patent application with the application date of September 14, 2017, the invention name of which is “An 8-shaped inductor structure integrated on a semiconductor and a semiconductor structure”, and the application number is 201710828109.8 (the publication number is CN107731793 B), discloses an inductor structure based on a double 8-shaped structure, which can only reduce the number of jumpers (the overlapping part is reduced from 5 times to 3 times, which is in line with the theoretical number of jumpers: theoretically, an N-turn coil will undergo at least N-1 jumpers) but cannot fundamentally meet the performance requirements at high frequencies. Summary of the invention

[0003] According to an embodiment of the present invention, the quasi-figure-8 structure inductor device includes a resonant inductor forming a first loop, a load inductor forming a second loop, and a current amplification circuit coupled between the resonant inductor and the load inductor, wherein: a first current in the first loop is amplified by the current amplification circuit to form a second current in the second loop, the direction of the first current is opposite to the direction of the second current, and the ratio of the second current to the first current is equal to the ratio of the inductance value of the load inductor to the inductance value of the resonant inductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0005] Figure 1 A schematic diagram of the structure of a traditional 8-shaped inductor device is shown.

[0006] Figure 2 A schematic structural diagram of an inductor device having a figure-8 structure according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0007] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, parts and algorithms without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention. In addition, it should be noted that the term "A is connected to B" used here can mean "A is directly connected to B" and can also mean "A is indirectly connected to B via one or more other elements".

[0008] In some high-frequency circuits, in addition to the resonant inductor in the oscillator, there is also a load inductor in the driver or amplifier, where the load inductor is related to and affected by the resonant inductor. For example, the resonant inductor in the oscillator is an active inductor, and the load inductor in the driver or amplifier is a passive inductor. Only when the resonant inductor as an active inductor works, the load inductor as a passive inductor will work.

[0009] Usually, the sum of the magnetic fluxes interlinked by each turn of a coil with current I is called the flux linkage ψ of the coil. If the magnetic flux interlinked by each turn of the coil is Φ, and the number of turns of the coil is N, then the flux linkage ψ of the coil = NΦ. When the current I in the coil changes with time, the flux linkage Ψ of the coil also changes with time. According to the law of electromagnetic induction, the change of the flux linkage Ψ will induce a self-induced electromotive force e in the coil. L , whose value is

[0010] e L =-dψ / dt (1)

[0011] Here, the self-inductance L of the coil is the self-induced electromotive force e of the coil. L The ratio of the current I with respect to the time derivative dI / dt and prefixed with a negative sign, that is,

[0012]

[0013] Among them, ψ and e L The positive direction of ψ and I all conform to the right-hand screw rule.

[0014] Combining equation (1) and equation (2), we can get

[0015]

[0016] dψ=LdI (4)

[0017] That is, the change of the magnetic flux ψ of the coil is proportional to the change of the current I, and its value depends on the inductance value of the inductor L and the magnitude of the alternating current flowing through the inductor L, that is, Φ=L·I, and the direction also conforms to the right-hand spiral rule.

[0018] Figure 1 FIG. 2 shows a schematic diagram of a conventional 8-shaped inductor device. Figure 1 As shown, the 8-shaped structure inductor device 100 is evolved from a coil inductor with two turns of winding wire, wherein one turn of winding wire is mirror-folded in the horizontal direction to form another turn of winding wire, and the two turns of winding wire have the same shape and size. By twisting, the currents flowing through the upper winding wire and the lower winding wire are in opposite directions and equal in magnitude, so that the upper winding wire and the lower winding wire can generate two parallel magnetic fields of equal magnitude and opposite directions, ensuring that the entire inductor device is in the horizontal direction (i.e., along Figure 1 The magnetic flux (shown by the dotted line in the figure) is 0.

[0019] like Figure 1 As shown, although the 8-shaped inductor device 100 can reduce external electromagnetic radiation in the horizontal direction, other inductors (for example, Figure 1 The inductor 102 shown in the figure 8 is placed in the horizontal direction of the inductor device 100 to achieve good inductor isolation, but this is at the expense of circuit area (i.e., the inductor device of the figure 8 structure uses the upper and lower windings arranged in the shape of an 8 to achieve the function of a single inductor, and occupies a larger circuit area).

[0020] Based on the above analysis, an 8-shaped structure inductor device according to an embodiment of the present invention is proposed, in which two conventional spiral inductors, a load inductor and a resonant inductor, are used to construct two magnetic fluxes with equal strength and opposite polarity. The two magnetic fluxes can cancel each other out in the horizontal direction, thereby reducing external electromagnetic radiation in the horizontal direction.

[0021] Figure 2 FIG. 2 shows a schematic diagram of a structure of an inductor device having a figure-8 structure according to an embodiment of the present invention. Figure 2 As shown, in some embodiments, the quasi-figure-8 structure inductor device 200 includes a resonant inductor 202 forming a first loop, a load inductor 204 forming a second loop, and a current amplifying circuit 206 coupled between the resonant inductor 202 and the load inductor 204, wherein: the first current I in the first loop 1 After being amplified by the current amplifier circuit 206, a second current I in the second loop is formed 2 , the first current I 1 The direction of the second current I2 The direction is opposite, and the second current I 2 With the first current I 1 The ratio between them is equal to the inductance value L of the load inductor 204 2 The inductance value L of the resonant inductor 202 1 The ratio between 2 =kI 1 , k = L 2 / L 1 is the gain of the current amplifier circuit 206). In this way, the magnetic flux of the first loop and the magnetic flux of the second loop can be two magnetic fluxes of equal strength and opposite direction, thereby canceling each other out. It should be noted that the resonant inductor 202 forming the first loop and the load inductor 204 forming the second loop do not have to have the same external dimensions, and can be independently designed according to the functions to be implemented, so as to obtain the optimal performance of each with the optimal shape and size.

[0022] like Figure 2 As shown, in some embodiments, the resonant inductor 202 is included in the oscillator, and the load inductor 204 is included in the driver or amplifier. For example, the resonant inductor 202 is implemented as an active inductor, and the load inductor 204 is implemented as a passive inductor. Only when the resonant inductor 202 as an active inductor works, the load inductor 204 as a passive inductor will work.

[0023] like Figure 2 As shown, in some embodiments, the current amplification circuit 206 can be implemented as an inverting current amplifier and coupled between the resonant inductor 202 and the load inductor 204 (correspondingly, the in-phase ports of the first loop and the second loop are coupled to each other), or can be implemented as a in-phase current amplifier and coupled between the resonant inductor 202 and the load inductor 204 (correspondingly, the in-phase ports of the first loop and the second loop are cross-coupled), so that the first current I in the first loop 1 and the second current I in the second loop 2 are currents with opposite directions. According to the right-hand screw rule, the two magnetic fluxes generated by the first loop and the second loop are parallel and in opposite phases. For example, the wavelength of a 30GHz electromagnetic wave is 10mm. Assuming that the first loop and the second loop are 100um apart, a phase shift of 3.6° will be generated. Therefore, the phase shift generated by the transmission of the electrical signal from the first loop to the second loop can be ignored.

[0024] like Figure 2 As shown, the quasi-figure-8 structure inductor device 200 can be regarded as a distanced figure-8 double loop, and the magnetic flux in the horizontal direction is 0. When another inductor is placed in the horizontal direction of the quasi-figure-8 structure inductor device 200, the influence of their mutual inductance will be significantly reduced.

[0025] The influence of the mutual inductance between the two inductors can be obtained by deriving a complete electromagnetic field calculus equation, but this process is quite cumbersome and difficult. Computer-implemented electromagnetic field simulation can well replace this process. The following Table 1 shows the improvement of the inductance isolation between the ordinary inductor and the third inductor of the quasi-8-structure inductor device 200 and the 8-structure inductor device 100 at 10GHz.

[0026] Table 1

[0027]

[0028] It can be seen from Table 1 that, when the distance between the third inductor and the 8-shaped structure inductor device 100 is equal, the improvement of the inductance isolation between the 8-shaped structure inductor device 100 and the third inductor is 32 dB compared with the inductance isolation between the common inductor and the third inductor. Correspondingly, when the distance between the third inductor and the 8-shaped structure inductor device 200 is equal, the improvement of the inductance isolation between the 8-shaped structure inductor device 200 and the third inductor is related to the spacing between the first loop and the second loop in the 8-shaped structure inductor device 200. The shorter the spacing, the better the improvement, and it is close to the improvement of the 8-shaped structure inductor device 100.

[0029] It should be understood that the relative positions of the first loop and the second loop in the quasi-figure-8 structure inductor device 200 can be reversed (i.e., the second loop is the upper loop and the first loop is the lower loop). In addition, the first loop and the second loop in the quasi-figure-8 structure inductor device 200 can also be implemented as a left loop and a right loop, for example, the second loop is the left loop and the first loop is the right loop, or the first loop is the left loop and the second loop is the right loop, in which case the magnetic fluxes of the first loop and the second loop can cancel each other in the vertical direction, thereby reducing the external electromagnetic radiation in the vertical direction.

[0030] Compared with the inductor device 100 with a figure-8 structure, the inductor device 200 with a figure-8-like structure can use a figure-8 structure to realize the functions of two independent inductor devices, thereby saving circuit area.

[0031] The present invention can be implemented in other specific forms without departing from its spirit and essential features. For example, the algorithms described in the specific embodiments can be modified, and the system architecture does not depart from the basic spirit of the present invention. Therefore, the current embodiments are regarded as exemplary and non-restrictive in all aspects, and the scope of the present invention is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalent scope of the claims are thus included in the scope of the present invention.

Claims

1. An 8-shaped structure inductor device, comprising a resonant inductor forming a first loop, a load inductor forming a second loop, and a current amplification circuit coupled between the resonant inductor and the load inductor, wherein: The first current in the first loop is amplified by the current amplifier circuit to form a second current in the second loop, the direction of the first current is opposite to the direction of the second current, and the ratio of the second current to the first current is equal to the ratio of the inductance value of the load inductor to the inductance value of the resonant inductor.

2. The quasi-figure-8 structure inductor device according to claim 1, wherein: The resonant inductor is included in an oscillator, and the load inductor is included in a driver or an amplifier.

3. The quasi-figure-8 structure inductor device according to claim 1, wherein: The resonant inductor is implemented as an active inductor, and the load inductor is implemented as a passive inductor. The load inductor as the passive inductor operates only after the resonant inductor as the active inductor operates.

4. The quasi-figure-8 structure inductor device according to claim 1, wherein: The resonant inductor and the load inductor have different dimensions.

5. The quasi-figure-8 structure inductor device according to claim 1, wherein: The current amplification circuit is implemented as an inverting current amplifier.

6. The quasi-figure-8 structure inductor device according to claim 5, wherein: In-phase ports of the first loop and the second loop are coupled to each other.

7. The quasi-figure-8 structure inductor device according to claim 1, wherein: The current amplification circuit is implemented as a non-inverting current amplifier.

8. The quasi-figure-8 structure inductor device according to claim 7, wherein: Different phase ports of the first loop and the second loop are cross-coupled.

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