A miniaturized hybrid integrated YIG frequency synthesizer

Abstract

The present invention discloses a miniaturized hybrid integrated YIG frequency synthesizer, belonging to the technical field of microwave components, which includes an upper magnetic circuit (1) and a lower magnetic circuit (7) that are joined together. An oscillation circuit board (2), a YIG ball rod assembly (3), a phase-locked circuit board (4), a microwave connector A (5), a microwave connector B (6), a drive coil (8), a pole column (9), a control circuit board (10), and a low-frequency connector (11) are integrated inside the upper magnetic circuit (1) and the lower magnetic circuit (7). The structure of the present invention makes the height of the YIG frequency synthesizer consistent with the height of a single discrete miniaturized YTO, and significantly reduces the height compared to the conventional YIG frequency synthesizer. The control circuit board, the phase-locked circuit board, their installation structures inside the frequency synthesizer box body, and electrical interconnection structures such as wire bonding and elastic probes all play important roles in reducing the length and width dimensions of the frequency synthesizer. The size of the YIG frequency synthesizer of the present invention can be reduced by more than 50%.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave components, and particularly to a miniaturized hybrid integrated YIG frequency synthesizer. Background Art

[0002] A frequency synthesizer can provide microwave signals with fixed or variable frequencies, and is mainly used in systems such as microwave testing, communication, radar, and electronic countermeasure, as the local oscillator unit of receivers and transmitters.

[0003] Frequency synthesizers are widely used, and mainly include frequency synthesizers based on various oscillation sources such as DDS (Direct Digital Synthesis), VCO (Voltage Controlled Oscillator), DRO (Dielectric Resonator Oscillator), and YTO (YIG Magnetically Tuned Oscillator, or "YIG oscillator").

[0004] Among them, the YIG frequency synthesizer based on YTO and phase-locked loop has the advantages of wide operating frequency band and low phase noise. Compared with the VCO frequency synthesizer that can also operate in a wide frequency band, the YIG frequency synthesizer has obvious advantages in noise performance and is often used in high-performance microwave systems.

[0005] However, the YIG frequency synthesizer also has its own disadvantages. One obvious disadvantage is that its volume is relatively large. The main reasons for the large volume of the YIG frequency synthesizer are as follows:

[0006] 1) Compared with VCO, YTO cannot be chip-sized at present. Even the currently smallest "miniaturized" YTO is much larger than a monolithic VCO.

[0007] 2) The frequency tuning method of YTO is based on magnetic field tuning, and the magnetic field is driven by current. Therefore, compared with the VCO frequency synthesizer, in addition to the control and phase-locked loop circuits, the YIG frequency synthesizer also requires two driver circuits, a main driver and a secondary driver. The main driver corresponds to the main coil of YTO and is used to convert the DAC output voltage into a driving current to achieve coarse tuning of the YTO oscillation frequency. The secondary driver corresponds to the secondary coil of YTO and is used to convert the phase discrimination error voltage generated by the phase-locked loop into a current to achieve phase-locked control.

[0008] Specifically, the structure of the current YIG frequency synthesizer is as Figure 1 and 2 shown. Generally, it includes a frequency synthesizer box cover a, YTO b, a frequency synthesizer box body c, an external connector d, a circuit board e, including control, drive, and phase-locked units and a frequency synthesizer box bottom plate f. It can be seen from the figure that this structure is based on a discrete YTO. The magnetic circuit (outer shell) of YTO and the box body of the frequency synthesizer are two independent parts. YTO is installed in the frequency synthesizer box in the form of an independent device (discrete type). The main disadvantages of this structure are as follows:

[0009] 1) The total height of the frequency synthesizer, excluding the height of the YTO, also includes the bottom plate f of the box body, the cover plate a, the circuit board e, and the necessary space height. Therefore, its total height is necessarily much greater than the height of the discrete YTO. As shown in Figure 1 the figure, its overall height reaches 18 mm, and both the length and width are 40 mm;

[0010] 2) Secondly, as an independent device, the YTO inevitably uses connection devices such as glass insulators as its electrical terminals to interconnect with the peripheral circuit. This not only requires more space, but also the mutual conversion of different transmission line structures is not conducive to the impedance matching of microwave transmission;

[0011] That is, currently, the YIG frequency synthesizer generally has a relatively large volume and does not meet the development requirements of miniaturization and integration of high-performance microwave devices. Summary of the Invention

[0012] The object of the present invention is to provide a miniaturized hybrid integrated YIG frequency synthesizer to solve the above problems.

[0013] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0014] A miniaturized hybrid integrated YIG frequency synthesizer includes an upper magnetic circuit and a lower magnetic circuit that are joined together. An oscillation circuit board, a YIG ball rod assembly, a phase-locked circuit board, a microwave connector A, a microwave connector B, a drive coil, a pole column, a control circuit board, and a low-frequency connector are integrated inside the upper magnetic circuit and the lower magnetic circuit.

[0015] The present invention provides a miniaturization solution for the YIG frequency synthesizer. Specifically, it adopts the design concept of combining the YTO magnetic circuit with the frequency synthesizer box body. There is no discrete YTO in the YIG frequency synthesizer; at the same time, based on the design concept of hybrid integration, circuit units such as oscillation, control, and phase-locking are all integrated inside the magnetic circuit cavity;

[0016] That is, there is no discrete YTO inside the frequency synthesizer of the present invention, and the frequency synthesizer box body is the magnetic circuit of the YTO; when the upper and lower parts of the frequency synthesizer are combined, a complete YTO magnetic circuit structure is formed; the total height of the frequency synthesizer is the same as the height of the discrete miniaturized YTO, without additional height, thus achieving the effect of significantly reducing the height of the frequency synthesizer.

[0017] Among the above components, from the perspective of individual parts, the oscillation circuit board, the YIG ball rod assembly (including the YIG ball, beryllium ceramic rod, sleeve, and support), microwave connector A, microwave connector B, drive coil, and low-frequency connector are prior arts, that is, these parts do not need to be redesigned; while the phase-locked circuit board, pole column, and control circuit board need to be improved or redesigned according to the structure of the hybrid integrated YIG frequency synthesizer. Specifically:

[0018] 1) Both the control circuit board and the phase-locked circuit board adopt LTCC substrate technology. All ICs are bare chips and are installed by embedding in cavities dug in the LTCC substrate to reduce the overall height of the circuit. In terms of circuit layout, it needs to be adjusted according to the overall layout inside the frequency synthesizer. For example, the interconnection between the control circuit board and the low-frequency connector, the interconnection between the phase-locked circuit board and the oscillation circuit board, the interconnection between the phase-locked circuit board and microwave connector A and microwave connector B, and the interconnection relationship between the control circuit board and the phase-locked circuit board determine the positions of the input and output terminals of the circuit board, etc.

[0019] 2) The pole column adopts the above-mentioned bias design and the "parabolic" depression design of the magnetic pole surface.

[0020] That is, from the perspective of the overall structural layout, the positions of all the above parts in the hybrid integrated YIG frequency synthesizer need to be rearranged, which is very different from the structure of the existing YIG frequency synthesizer.

[0021] As a preferred technical solution: The oscillation circuit board and the phase-locked circuit board are both integrated in the inner cavity of the upper magnetic circuit, and electrical interconnection is achieved between the oscillation circuit board and the phase-locked circuit board by means of gold wire bonding; the control circuit board is integrated in the inner cavity of the lower magnetic circuit, and an electromagnetic shielding board is provided between the phase-locked circuit board and the control circuit board. The above integrated arrangement is more conducive to miniaturization without affecting the performance of the frequency synthesizer.

[0022] As a further preferred technical solution: It further includes elastic probes, and electrical interconnection is achieved between the phase-locked circuit board and the control circuit board through the elastic probes.

[0023] When the upper magnetic circuit and the lower magnetic circuit are combined, the contacts of the elastic probes are automatically connected, avoiding the wire welding method and facilitating the disassembly, installation, and maintenance of the frequency synthesizer.

[0024] As an even more preferred technical solution: The elastic probes are nine in number and are arranged in two rows.

[0025] The probes are used for electrical interconnection (power lines, control signal lines, etc.) between the circuit boards in the upper and lower magnetic circuits. The number here is nine, which is determined by the specific design of the embodiment and can also be other numbers. The arrangement of all the probes in two rows is determined by the space layout of the embodiment and can also be in various forms such as three rows, four rows, or circular arrangement.

[0026] The elastic probe itself is a general part, but its installation structure in the present invention belongs to a new design. As Figure 3 and Figure 4 , according to the arrangement of nine elastic probes in two rows in the embodiment, a special support is designed. Nine through holes are correspondingly arranged on the support, and the probes pass through the holes of the support. The support is installed on the lower magnetic circuit. At this time, one end of the probe contacts the corresponding contact of the control circuit board installed in the inner cavity of the lower magnetic circuit. When the upper and lower magnetic circuits are combined, the elastic probe is compressed and the other end of the probe contacts the corresponding contact of the phase-locked circuit board installed in the inner cavity of the upper magnetic circuit, so as to realize the electrical interconnection between the circuit boards in the upper and lower magnetic circuits.

[0027] As a preferred technical solution: the pole column is arranged deviating from the magnetic circuit central axis, that is, the original pole column located at the center of the magnetic circuit is improved to a pole column offset design. The pole column offset design is to leave the best layout space for components such as the control circuit board and the phase-locked circuit board. For example, if there is a column in the center of a house, it will have a serious impact on placing furniture; similarly, if the pole column is on the magnetic circuit central axis, it will be very difficult for other circuits to achieve a compact layout, resulting in difficulty in realizing the miniaturization design of the YIG frequency synthesizer described in the present invention.

[0028] In addition, it is further preferred that the magnetic pole surface of the pole column adopts a "parabolic surface" concave design, aiming to improve the uniformity of the magnetic field in the magnetic circuit air gap.

[0029] Compared with the prior art, the advantages of the present invention are as follows: the present invention provides a structural solution for a hybrid integrated YIG frequency synthesizer, realizing a technical breakthrough in the miniaturization design of a frequency synthesizer based on YIG oscillator technology. This structure makes the height of the YIG frequency synthesizer consistent with the height of a single discrete miniaturized YTO, and significantly reduces the height compared with that of a conventional YIG frequency synthesizer; the control circuit board, the phase-locked circuit board, their installation structures inside the frequency synthesizer box body, and electrical interconnection structures such as wire bonding and elastic probes all play an important role in reducing the length and width dimensions of the frequency synthesizer. The size of the YIG frequency synthesizer of the present invention is reduced by more than 50% compared with that of a conventional YIG frequency synthesizer. Description of the Drawings

[0030] Figure 1 is a cross-sectional view of a YIG frequency synthesizer in the prior art;

[0031] Figure 2 is a schematic plan view of a YIG frequency synthesizer in the prior art;

[0032] Figure 3 is a cross-sectional view of an embodiment of the present invention;

[0033] Figure 4Schematic diagram of the planar structure of the embodiment of the present invention;

[0034] Figure 5 Longitudinal sectional view of the pole column and the magnetic circuit air gap in the embodiment of the present invention;

[0035] Figure 6 Discrete YTO magnetic circuit simulation model of the prior art;

[0036] Figure 7 Curve of the magnetic field at the air gap of the discrete YTO magnetic circuit changing with the X coordinate in the prior art;

[0037] Figure 8 Magnetic circuit simulation model of the frequency synthesizer in this embodiment;

[0038] Figure 9 Curve of the magnetic field at the air gap of the magnetic circuit of the frequency synthesizer in this embodiment changing with the X coordinate.

[0039] In the figure: 1. Upper magnetic circuit; 2. Oscillation circuit board; 3. YIG small ball rod assembly; 4. Phase-locked circuit board; 5. Microwave connector A; 6. Microwave connector B; 7. Lower magnetic circuit; 8. Drive coil; 9. Pole column; 10. Control circuit board; 11. Low-frequency connector; 12. Electromagnetic shielding plate; 13. Elastic probe; 14. Elastic probe support; a. Box cover; b. YTO; c. Box body; d. Connector; e. Circuit board; f. Box bottom plate; g. "Parabolic" concave structure. Detailed implementation manners

[0040] The present invention will be further described below in conjunction with the accompanying drawings.

[0041] Embodiment:

[0042] Refer to Figure 3 and 4 , a miniaturized hybrid integrated YIG frequency synthesizer, including an upper magnetic circuit 1 and a lower magnetic circuit 7 that are joined together. The upper magnetic circuit 1 and the lower magnetic circuit 7 internally integrate an oscillation circuit board 2, a YIG small ball rod assembly 3, a phase-locked circuit board 4, a microwave connector A 5, a microwave connector B 6, a drive coil 8, a pole column 9, a control circuit board 10, and a low-frequency connector 11;

[0043] Both the oscillation circuit board 2 and the phase-locked circuit board 4 are integrated in the inner cavity of the upper magnetic circuit 1, and electrical interconnection is achieved between the oscillation circuit board 2 and the phase-locked circuit board 4 by means of gold wire bonding; the control circuit board 10 is integrated in the inner cavity of the lower magnetic circuit 7, and an electromagnetic shielding plate 12 is provided between the phase-locked circuit board 4 and the control circuit board 10;

[0044] It further includes elastic probes 13. There are nine elastic probes 13 in this embodiment, which are arranged in two rows. Electrical interconnection between the phase-locked circuit board 4 and the control circuit board 10 is achieved through the elastic probes 13.

[0045] Specifically, as Figure 3 and Figure 4 , a dedicated elastic probe support 14 is designed according to the arrangement of the nine elastic probes 13 in two rows in this embodiment. Nine through holes are correspondingly arranged on the elastic probe support 14. The elastic probes 13 pass through the holes of the elastic probe support 14, and the elastic probe support 14 is installed on the lower magnetic circuit 7. At this time, one end of the elastic probe 13 contacts the corresponding contact of the control circuit board 10 installed in the inner cavity of the lower magnetic circuit 7.

[0046] The pole post 9 is arranged deviating from the magnetic circuit central axis; referring to Figure 5 , a "parabolic rotation scan" depression design measure is taken for the magnetic pole surface of the pole post 9.

[0047] The YIG small ball rod assembly 3 is installed on the upper magnetic circuit 1 and on the same platform as the oscillation circuit board 2. Among them, the YIG small ball is at the center of the magnetic circuit air gap (on the axis of the pole post), and the other end of the small ball rod is perpendicular to a side wall of the magnetic circuit. An adjustment hole is left at the position on this side wall opposite to the YIG small ball rod assembly. After the upper magnetic circuit 1 and the lower magnetic circuit 7 are assembled, the angle of the small ball rod can be finely adjusted through this adjustment hole; after the frequency synthesizer debugging is completed, this adjustment hole is sealed.

[0048] Both the microwave connectors A5 and B6 are installed on the lower magnetic circuit 7, and their center conductors are connected to the phase-locked circuit board 4; the microwave connector A5 is a signal output terminal. Inside the frequency synthesizer, a microwave signal is generated by the oscillation circuit board 2 and is transmitted to the microwave connector A5 through components such as the amplifier, directional coupler, and filter on the phase-locked circuit board 4 and then output to the outside; the microwave connector B6 is a reference signal input terminal. The external reference signal enters the frequency synthesizer through the connector B6 and reaches the phase discriminator chip on the phase-locked circuit board 4 through the transmission line to provide a reference signal for phase discrimination; the low-frequency connector 11 is installed on the upper magnetic circuit 1, and its core wire terminal is connected to the control circuit board 10 for the interconnection of the frequency synthesizer power input and control lines.

[0049] With the above highly integrated structure of this embodiment, the height of this YIG frequency synthesizer can be reduced to 8 mm, and the length and width can also be reduced to 35 mm. Compared with the traditional synthesizer, the volume is reduced by about 66%.

[0050] The highly integrated structure of the present invention is different from other existing high-density integrated microwave devices in terms of technical difficulties, or rather, the biggest difference lies in that the housing of the frequency synthesizer itself is the magnetic circuit of the YIG oscillator. Therefore, the housing design not only needs to consider the structural installation characteristics, but also must take into account the magnetic properties of the magnetic circuit at the same time. There are relatively high requirements for the magnetic field uniformity of the magnetic circuit air gap (the air gap between the lower magnetic circuit pole column and the upper magnetic circuit platform, and the YIG sphere is located at the center of this air gap); due to the offset design of the pole column 9 in this application, the structure around the pole column 9 is asymmetric, so it has a certain impact on the magnetic field uniformity of the air gap;

[0051] In order to weaken or eliminate the above-mentioned influence, the present embodiment further takes optimization design measures for the magnetic field uniformity of the magnetic circuit, such as Figure 5 As shown, a "parabolic" concave structure g is adopted on the pole magnetic pole surface, so that the magnetic field distribution in the air gap meets the uniformity requirements. Figure 5 In the figure, in order to more clearly show the "parabolic" concave structure, the figure is relatively exaggerated; the actual diameter of the pole column is 5 mm, the height of the air gap is 1 mm, and the central depth of the "parabolic" concave structure g is about 0.04 mm;

[0052] In Figure 7 、 Figure 9 In the figure, it corresponds to the relatively flat section of the curve within the magnetic circuit air gap, and the rest is the part outside the air gap. It can be seen from the figure that after optimization, the magnetic field gradient within 1.6 mm of the center of the magnetic circuit air gap of the frequency synthesizer in this embodiment (the diameter of the YIG sphere is Φ0.28 mm, and the design considers that the cross-sectional diameter of the air gap field uniform area is not less than five times the diameter of the sphere) is about 0.263 (Oe / mm), which is slightly better than the magnetic field gradient of 0.368 (Oe / mm) within the air gap of the discrete YTO magnetic circuit. (Note: The magnetic field gradient is the ratio of the maximum difference in the magnetic field within the air gap field uniform area to the diameter of the cross-section of the uniform area).

[0053] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A miniaturized hybrid integrated YIG frequency synthesizer, characterized in that: it includes a mutually joined upper magnetic circuit (1) and a lower magnetic circuit (7), and an oscillation circuit board (2), a YIG ball rod assembly (3), a phase-locked circuit board (4), a microwave connector A (5), a microwave connector B (6), a drive coil (8), a pole column (9), a control circuit board (10) and a low-frequency connector (11) are integrated inside the upper magnetic circuit (1) and the lower magnetic circuit (7); the oscillation circuit board (2) and the phase-locked circuit board (4) are both integrated in the inner cavity of the upper magnetic circuit (1), and electrical interconnection is realized between the oscillation circuit board (2) and the phase-locked circuit board (4) by means of gold wire bonding; the control circuit board (10) is integrated in the inner cavity of the lower magnetic circuit (7), and an electromagnetic shielding board (12) is arranged between the phase-locked circuit board (4) and the control circuit board (10); the pole column (9) is arranged deviating from the magnetic circuit central axis, and a parabolic depression is arranged on the magnetic pole surface of the pole column (9).

2. The miniaturized hybrid integrated YIG frequency synthesizer according to claim 1, characterized in that: it further includes an elastic probe (13), and electrical interconnection is realized between the phase-locked circuit board (4) and the control circuit board (10) through the elastic probe (13).

3. The miniaturized hybrid integrated YIG frequency synthesizer according to claim 2, characterized in that: the elastic probe (13) is nine in number and arranged in two rows.

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