Multi-channel KU-band high-duty-ratio TR module and implementation method thereof

Abstract

The invention provides a multi-channel KU-band high-duty-ratio TR module and an implementation method thereof, and relates to the technical field of radar equipment. The layout mode that the power supply low-frequency board is arranged on the radio frequency channel is adopted, the bottom of the radio frequency channel is directly embedded into the cavity, the radio frequency microstrip line has good transmission matching and extremely low insertion loss, no device or power supply low-frequency board is arranged on the back face of the chip with high heat consumption, and therefore the heat dissipation performance is improved; by designing a receiving channel and a transmitting channel of a radio frequency channel, the effect of multi-channel KU wave band high duty ratio is achieved, and a hardware basis is provided for self-inspection and self-calibration of a radar by combining a circulator with an antenna channel and a calibration channel. The power supply low-frequency board is arranged by adopting a PCB (Printed Circuit Board) laminated structure, power supply circuit division is carried out by arranging an insulating groove, and a traditional appearance through groove is replaced by a deep control groove, so that the problem that a gold wire cannot be bonded is perfectly solved, and the heat dissipation problem of the TR module is further solved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar equipment, and in particular to a multi-channel KU-band high-duty-cycle TR module and an implementation method thereof. Background Art

[0002] Modern military and civilian phased array radars, especially missile-borne, ship-borne, airborne and vehicle-borne phased array radar systems, are developing towards miniaturization, lightweight, high reliability and low cost, which puts increasingly higher requirements on the design of TR modules, an important module of phased array radar.

[0003] The size of a phased array radar is affected by the number of TR module channels, which in turn is affected by the radar's transmit power. Currently, the typical tile-type Ku-band TR module used in military and civilian phased array radars has a single-channel transmit power of 1W and a duty cycle of ≤20%. The typical brick-type Ku-band TR module has a single-channel transmit power of 10W and a duty cycle of ≤20%.

[0004] Very few single channels can reach 20W, but the duty cycle is relatively low; this is mainly affected by the heat dissipation of the TR module body. If the heat dissipation performance is improved, miniaturization cannot be achieved. If miniaturization is achieved, there will be restrictions on the number of channels and duty cycle, and it is impossible to take into account both the high duty cycle and miniaturization of the multi-channel KU band.

[0005] Therefore, we need to provide a Ku-band TR module to solve the technical problem that the existing technology is incompatible with miniaturization and heat dissipation performance, so as to achieve a multi-channel KU band high duty cycle. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a multi-channel KU-band high-duty-cycle TR module and its implementation method, aiming to solve the technical problem that the existing technology is incompatible with miniaturization and heat dissipation performance, reduce the size of the KU-band phased array radar, and take into account high duty cycle and output power, making the application scenarios of phased array radar more extensive.

[0007] To achieve the above objectives, the present application proposes a multi-channel KU band high duty cycle TR module and its implementation method, including a main housing, multiple RF channels, a power supply low frequency board, a sintering fixture and a cover plate: wherein, The RF channel is composed of multiple components connected in series via RF microstrip lines. A cavity is provided at the bottom of the main housing and the RF channel is sintered on the cavity. The components are embedded and sintered on the upper surface of the cavity, and the RF microstrip lines are buried on the upper surface of the cavity. The power supply low-frequency board is arranged on the front of the radio frequency channel and is provided with a groove at the position of the corresponding components; wherein the bottom of the power supply low-frequency board is in contact with the upper surface of the cavity, and the corresponding components are placed in the groove; The sintering fixture is fitted between the low-frequency power supply board and the cover plate, and the cover plate is buckled onto the main housing and sealed as a whole by welding; The main housing is provided with interface boards on the front and back respectively. The interface boards are provided with a plurality of channel interfaces which are electrically connected to the radio frequency channels respectively.

[0008] As a further solution, a wiring groove is further provided on the upper surface of the cavity; wherein the wiring groove is opened between the component and the radio frequency microstrip line and accommodates the gold wire used for gold wire bonding.

[0009] As a further solution, the radio frequency channel includes a receiving channel, a transmitting channel, an antenna channel and a calibration channel; wherein the receiving channel, the transmitting channel, the antenna channel and the calibration channel are electrically connected through a circulator.

[0010] As a further solution, the transmitting channel includes a first adjustable attenuator, a first power amplifier chip, a digitally controlled phase shifter, a second power amplifier chip, a second adjustable attenuator and a third power amplifier chip connected in series in sequence; wherein the output end of the third power amplifier chip is electrically connected to the circulator.

[0011] As a further solution, the receiving channel includes a limiter, a fourth power amplifier chip, a voltage-controlled attenuator, a fifth power amplifier chip and a third adjustable attenuator connected in series in sequence; wherein the input end of the limiter is electrically connected to the circulator.

[0012] As a further solution, the embedded cavity at the bottom of the chip used by the radio frequency channel is provided with a diamond carrier plate.

[0013] As a further solution, the power supply low-frequency board is arranged using a PCB stacking structure, and the power supply circuit is divided by providing an insulating groove.

[0014] As a further solution, the PCB stacking structure is provided by alternating copper layers and dielectric layers; wherein the dielectric layers are provided by a core board Core or a prepreg PP.

[0015] As a further solution, the components include active devices; wherein, the trenches corresponding to the active devices are set by depth-controlled grooves, and the depth-controlled grooves penetrate the PCB stacking structure through the upper large grooves and the lower small grooves, and form a stepped mesa at the intersection; the stepped mesa is set at the copper layer, and the active devices are bonded to the stepped mesa by gold wires.

[0016] As a further solution, the surfaces of the top copper layer, the bottom copper layer and the copper layer of the stepped mesas of the PCB stacked structure are further plated with nickel-palladium-gold layers.

[0017] Compared with related technologies, the multi-channel KU-band high-duty-cycle TR module and its implementation method provided by the present invention have the following advantages: 1. The present invention adopts a layout in which a low-frequency power supply board is set above the RF channel, and the bottom of the RF channel is directly embedded in the cavity. The RF microstrip line has good transmission matching and extremely low insertion loss. In addition, there are no devices or low-frequency power supply board on the back of the chip with high heat consumption, thereby achieving improved heat dissipation performance. 2. The present invention achieves a multi-channel KU band high duty cycle effect by designing the receiving channel and transmitting channel of the RF channel. In addition, the circulator is linked with the antenna channel and the calibration channel to provide a hardware foundation for the radar's self-test and self-calibration. 3. The power supply low-frequency board of the present invention is set up with a PCB stacking structure, and the power supply line is divided by setting an insulating groove; the PCB stacking structure is set by alternating copper layers and dielectric layers, and the traditional outer shape through grooves are replaced by controlled depth grooves, which perfectly solves the problem of gold wire bonding failure and then solves the heat dissipation problem of the TR module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 A schematic structural diagram of a multi-channel KU-band high-duty-cycle TR module and its implementation method provided by the present invention; Figure 2 A schematic diagram of the dimensions of the main housing provided by the present invention; Figure 3 A schematic diagram of the radio frequency channel structure provided by the present invention; Figure 4 A schematic diagram of the PCB stacking structure provided by the present invention; Figure 5 A schematic diagram of the temperature simulation results provided by the present invention; Among them, the figure markings are: 1. main shell; 2. cover plate; 3. power supply low-frequency board; 4. sintering fixture; 5. interface board; 6. channel interface.

[0021] The purpose, features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0023] Example 1 See also Figure 1 The embodiments of the present application provide a multi-channel KU-band high-duty-cycle TR module and its implementation method, which aims to solve the technical problem that existing technologies are incompatible with miniaturization and heat dissipation performance. It reduces the size of KU-band phased array radars while taking into account high duty cycle and output power, making the application scenarios of phased array radars more extensive. To achieve the above objectives, the present application proposes a multi-channel KU band high duty cycle TR module and its implementation method, including a main housing 1, multiple RF channels, a power supply low frequency board 3, a sintering fixture 4 and a cover plate 2: wherein, The RF channel is composed of multiple components connected in series through RF microstrip lines. A cavity is provided at the bottom of the main housing 1 and the RF channel is sintered on the cavity. The components are embedded and sintered on the upper surface of the cavity, and the RF microstrip lines are buried on the upper surface of the cavity. The power supply low-frequency board 3 is arranged on the front of the RF channel, and is provided with a groove at the position of the corresponding components; wherein the bottom of the power supply low-frequency board 3 is in contact with the upper surface of the cavity, and the corresponding components are placed in the groove; The sintering fixture 4 is fitted between the low-frequency power supply board 3 and the cover plate 2. The cover plate 2 is buckled onto the main housing 1 and sealed as a whole by welding. The main housing 1 is provided with interface boards 5 on the front and back, respectively. The interface boards 5 are provided with a plurality of channel interfaces 6 which are electrically connected to the radio frequency channels.

[0024] It should be noted that there are three common traditional TR module layout forms; among them, The first is a double-sided layout, with components and a single-layer RF microstrip line assembled on the front side, and the chip and RF microstrip line are directly sintered on the cavity; the power supply chip and the low-frequency multi-layer PCB are assembled on the back side, and the two printed circuit boards are interconnected through sintered low-frequency insulators; the advantage is good RF signal transmission effect, but the disadvantage is that the low-frequency PCB on the back side has poor heat dissipation and large size.

[0025] The second type is a single-sided layout, where high-frequency and low-frequency boards are mixed and pressed together, with the high and low frequencies made into one board. Components and power supply chips are sintered directly onto the mixed-pressed board. The advantage of the single-sided layout is its simple structure and small size. The disadvantage is that the chips are sintered onto the mixed-pressed board, resulting in poor heat dissipation. The third type is a single-sided layout, which is an improvement on the second type. Grooves are dug where the power amplifier chips are sintered onto the mixed-pressed board, allowing the heat-intensive chips to be sintered directly onto the cavity. The advantage is its simple structure, small size, and good heat dissipation. The disadvantage is that the ground plane of the coplanar waveguide is the second layer of the mixed-pressed board, while the ground plane of the chip is the cavity. The ground plane of the coplanar waveguide needs to be connected to the ground plane of the chip through vias. Vias become inductive at high frequencies such as the KU band, affecting the impedance matching of RF signal transmission, resulting in poor RF signal transmission.

[0026] In response to the limitations and shortcomings of the existing KU-band TR modules of phased array radars described above, this embodiment proposes a multi-channel KU-band high-duty-cycle TR module and its implementation method. This realizes a KU-band TR module with the advantages of small size, high power, high duty cycle, and low cost. This reduces the number of channels in the KU-band phased array radar TR module, that is, reduces the size of the KU-band phased array radar, while taking into account high duty cycle and output power, making the application scenarios of phased array radars more extensive.

[0027] like Figure 1 As shown, this embodiment adopts a layout in which the power supply low-frequency board 3 is set above the RF channel, and the bottom of the RF channel (RF microstrip line and components) is directly embedded in the cavity. There are no components and power supply low-frequency board 3 on the back of the components with high heat consumption. The back of the TR module main shell 1 is in direct contact with the radar main shell 1, so the TR module has very good heat dissipation.

[0028] In a specific embodiment, the RF microstrip line substrate material is a single-layer PTFE-ultra-thin glass fiber cloth. Such a substrate has a small dielectric constant and a small loss factor, so the RF microstrip line has good transmission matching and extremely low insertion loss; the main shell 1 and the cover 2 are made of aluminum alloy material, so the TR module can be made very light, which has the advantage of light weight.

[0029] like Figure 2 As shown, the TR module is fixed with screws for installation, which is more convenient and practical. The external connection method of the TR module adopts SMP-KK plug-in. The RF transmission loss is better than the RF cable connection method, the space utilization is higher, and the size of the radar will be reduced accordingly. The spacing between the input / output SMP connectors is 13mm, which meets the KU band antenna spacing requirements. The low-frequency connector uses the airtight type J30JM2. The TR module meets the airtight requirements.

[0030] When in use, the TR module amplifies the KU band transmission signal and then outputs it to the antenna end through the output SMP connector. The transmission includes digitally controlled phase shifting. The echo signal received from the antenna end is input to the receiving channel through the input SMP connector. The receiving channel undergoes limiting, low-noise amplification and voltage-controlled attenuation. The calibration channel can perform amplitude and phase calibration on the T / R channel.

[0031] The radio frequency channel of this embodiment includes a receiving channel, a transmitting channel, an antenna channel, and a calibration channel; wherein the receiving channel, the transmitting channel, the antenna channel, and the calibration channel are electrically connected via a circulator; The transmitting channel includes a first adjustable attenuator, a first power amplifier chip, a digitally controlled phase shifter, a second power amplifier chip, a second adjustable attenuator and a third power amplifier chip connected in series in sequence; wherein the output end of the third power amplifier chip is electrically connected to the circulator.

[0032] The receiving channel includes a limiter, a fourth power amplifier chip, a voltage-controlled attenuator, a fifth power amplifier chip and a third adjustable attenuator connected in series in sequence; wherein the input end of the limiter is electrically connected to the circulator.

[0033] Specifically, the TR module integrates the transceiver channel calibration function, so the radar can perform self-inspection and self-calibration without the use of an external darkroom, greatly shortening the testing and debugging time, as well as reducing the testing cost; the radar host has stronger adaptability in different environments.

[0034] In another specific embodiment, the radio frequency channel adopts Figure 3 With the circuit structure and component selection shown, the TR module can amplify a KU-band signal with a duty cycle of 30% and an input power of -5dBm to an output power of +46dBm (i.e., 40W) through 8 RF channels. It can amplify small KU-band signals by 24.5dB and reduce the noise figure by 4dB.

[0035] Example 2 See also Figure 4 In this embodiment, based on the embodiment 1, the power supply low-frequency board (3) is provided with a PCB stacking structure, and the power supply line is divided by providing an insulating groove; the PCB stacking structure is provided by alternating copper layers and dielectric layers; wherein the dielectric layer is provided by an inner core board Core or a prepreg sheet PP; The components include active devices; wherein, the trenches corresponding to the active devices are set by depth-controlled grooves, and the depth-controlled grooves penetrate the PCB stacking structure through the upper large grooves and the lower small grooves, and form a stepped mesa at the intersection; the stepped mesa is set at the copper layer, and the active devices are bonded to the stepped mesa by gold wires.

[0036] It should be noted that: Figure 3 The circuit structure requires stronger heat dissipation capability. The traditional power supply low-frequency board 3 is designed as a whole board. If the power supply low-frequency board 3 is covered on the RF channel, the heat dissipation performance on the RF channel will be seriously affected. In order to adapt to the layout of the above-mentioned power supply low-frequency board 3 set on the RF channel, this embodiment needs to further improve the power supply low-frequency board 3 so that the RF channel can perform double-sided heat dissipation.

[0037] like Figure 4 As shown, in this embodiment, the components and the RF microstrip line are connected by gold wire bonding (in Figure 4 In the circuit, the circulator and the power amplifier chip are connected to the RF microstrip line through gold wires); therefore, a wiring slot is also provided on the upper surface of the cavity (i.e. Figure 4 The wiring slot is provided between the components and the RF microstrip line and accommodates the gold wire used for gold wire bonding. The RF microstrip line is made of a single-layer PTFE-ultra-thin glass fiber cloth, which has an extremely low dielectric constant and a very small loss factor, thereby achieving good RF signal transmission effect. On this basis, the power supply low-frequency board 3 is set up with a PCB stacking structure, and the power supply line is divided by setting insulation grooves; the PCB stacking structure is set up alternately by copper layers and dielectric layers; among them, the dielectric layer is set by the inner core board Core or semi-cured sheet PP.

[0038] In yet another specific embodiment, Figure 4 A three-layer PCB stacking structure is adopted; among them, The first PCB layer is between ME1 and ME2, which is configured by upper and lower copper layers and a core board made of FR4 material in the middle. The second PCB layer is located between ME2 and ME3, and is constructed by upper and lower prepreg sheets (PP) (FR4 material), copper layers, and a core board (Core) made of FR4 material in the middle. The third PCB layer is above ME3, which is configured by upper and lower copper layers, an inner core board of FR4 material, a copper layer, and a prepreg sheet PP of FR4 material in the middle; among them, the patch device is set on the top of the third PCB layer.

[0039] The circulator is located between the two power supply lines. An insulating groove is formed by grooving and then setting an insulating layer. The insulating groove not only divides the power supply lines, but also plays a role in conduction and heat dissipation.

[0040] Furthermore, the TR module's low-frequency power supply board 3 is placed in front of the RF channel, with a groove cut into the board where the RF chip would be. This solves the problem of poor heat dissipation caused by the low-frequency power supply board 3 being located on the back of the traditional TR module. However, this also introduces another problem: the bonding point of the low-frequency power supply board 3 is far away from the bonding point of the RF channel, making it impossible to bond the gold wires of the active components.

[0041] In order to solve this problem, the power supply low-frequency board 3 of this embodiment adopts a controlled depth groove; wherein, the controlled depth groove penetrates the PCB stacking structure through the upper large groove and the lower small groove, and forms a stepped table at the intersection; the stepped table is set at the copper layer, and the active device is bonded to the stepped table by gold wire.

[0042] In this embodiment, the traditional through-grooves are replaced by controlled-depth grooves. The non-metallized controlled-depth grooves reduce the bonding distance between the RF channel and the low-frequency power supply board 3. The RF channel and the low-frequency power supply board 3 are interconnected, and the layout of the low-frequency power supply board 3 above the RF channel can be implemented, thereby reducing the bonding distance by 1 mm, perfectly solving the problem of gold wire being unable to bond, and then solving the heat dissipation problem of the TR module; and in places where bonding is required, namely: the surface of the top copper layer, the bottom copper layer and the stepped table copper layer of the PCB stacked structure is also plated with a nickel-palladium-gold layer, further enhancing the conductive performance and surface durability.

[0043] Furthermore, the main housing 1 and cover 2 are made of aluminum alloy, a currently mainstream housing material with advantages such as lightness, high strength, and a high cost-effectiveness. Because the expansion coefficients of aluminum alloy and chips differ, the heat-generating power amplifier chip and circulator are both equipped with a carrier plate. Since the power amplifier chip is the primary heat source for the TR module, the power amplifier chip carrier plate uses a diamond carrier plate with an extremely high thermal conductivity. This improves the thermal conductivity of the power amplifier, thereby increasing its operating efficiency, reducing heat generation, and improving heat dissipation from the TR module.

[0044] In summary, this embodiment adopts a layout in which the power supply low-frequency board 3 is arranged above the RF channel, and the bottom of the RF channel is directly embedded in the cavity, thereby achieving improved heat dissipation performance; on this basis, by designing the receiving channel and the transmitting channel of the RF channel, the effect of a multi-channel KU band high duty cycle is achieved, and the circulator is combined with the antenna channel and the calibration channel to link, providing a hardware foundation for the self-test and self-calibration of the radar; in addition, the power supply low-frequency board 3 is arranged with a PCB stacking structure, and the traditional outer shape through-slot is replaced by a controlled depth groove, which perfectly solves the problem of the inability to bond the gold wire, and then solves the heat dissipation problem of the TR module. Figure 4 The figure shows the heat dissipation simulation results of the TR module. When the ambient temperature is 25°C and the radar system has good heat dissipation, the maximum temperature of the TR module is 76.98.

[0045] The above are only some embodiments of the present application and are not intended to limit the patent scope of the present application. All equivalent structural transformations made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A multi-channel KU band high duty cycle TR module, characterized in that: It comprises a main housing (1), a plurality of radio frequency channels, a power supply low frequency board (3), a sintering fixture (4) and a cover plate (2): wherein, The radio frequency channel is composed of a plurality of components connected in series via radio frequency microstrip lines, a cavity is provided at the bottom of the main housing (1), and the radio frequency channel is sintered on the cavity; wherein the components are embedded and sintered on the upper surface of the cavity, and the radio frequency microstrip lines are buried on the upper surface of the cavity; The power supply low-frequency board (3) is arranged on the front of the radio frequency channel, and is provided with a groove at the position of the corresponding component; wherein the bottom of the power supply low-frequency board (3) is in contact with the upper surface of the cavity, and the corresponding component is placed in the groove; The sintering fixture (4) is fitted between the power supply low-frequency plate (3) and the cover plate (2), and the cover plate (2) is buckled onto the main housing (1) and sealed as a whole by welding; The main housing (1) is provided with interface boards (5) on the front and back, respectively. The interface boards (5) are provided with a plurality of channel interfaces (6) which are electrically connected to the radio frequency channels.

2. The multi-channel KU band high duty cycle TR module according to claim 1, characterized in that: The radio frequency channel includes a receiving channel, a transmitting channel, an antenna channel and a calibration channel; wherein the receiving channel, the transmitting channel, the antenna channel and the calibration channel are electrically connected through a circulator.

3. The multi-channel KU band high duty cycle TR module according to claim 2, characterized in that: The transmitting channel includes a first adjustable attenuator, a first power amplifier chip, a digitally controlled phase shifter, a second power amplifier chip, a second adjustable attenuator and a third power amplifier chip connected in series in sequence; wherein the output end of the third power amplifier chip is electrically connected to the circulator.

4. The multi-channel KU band high duty cycle TR module according to claim 2, characterized in that: The receiving channel includes a limiter, a fourth power amplifier chip, a voltage-controlled attenuator, a fifth power amplifier chip and a third adjustable attenuator connected in series in sequence; wherein the input end of the limiter is electrically connected to the circulator.

5. A method for implementing a multi-channel KU band high duty cycle TR module, applied to a multi-channel KU band high duty cycle TR module according to any one of claims 1 to 4, characterized in that: The power supply low-frequency board (3) is arranged using a PCB stacking structure, and the power supply circuit is divided by arranging insulating grooves; the PCB stacking structure is arranged by alternating copper layers and dielectric layers; wherein the dielectric layer is arranged by an inner core board Core or a prepreg PP; The components include active devices; wherein, the trenches corresponding to the active devices are set by depth-controlled grooves, and the depth-controlled grooves penetrate the PCB stacking structure through the upper large grooves and the lower small grooves, and form a stepped mesa at the intersection; the stepped mesa is set at the copper layer, and the active devices are bonded to the stepped mesa by gold wires.

6. The method for implementing a multi-channel KU band high duty cycle TR module according to claim 5, characterized in that: The upper surface of the cavity is further provided with a wiring groove, wherein the wiring groove is opened between the component and the radio frequency microstrip line and accommodates the gold wire used for gold wire bonding.

7. The method for implementing a multi-channel KU band high duty cycle TR module according to claim 5, characterized in that: The PCB stacking structure is a three-layer PCB stacking structure, including a first PCB layer, a second PCB layer and a third PCB layer; wherein, The first PCB layer is configured by upper and lower copper layers and an inner core board Core made of FR4 material in the middle; the second PCB layer is configured by upper and lower prepregs PP made of FR4 material, a copper layer and an inner core board Core made of FR4 material in the middle; the third PCB layer is configured by upper and lower copper layers, an inner core board Core made of FR4 material, a copper layer and an inner core board PP made of FR4 material in the middle.

8. The method for implementing a multi-channel KU band high duty cycle TR module according to claim 7, characterized in that: The components include surface mount devices, wherein the surface mount devices are arranged on top of the third PCB layer.

9. The method for implementing a multi-channel KU band high duty cycle TR module according to claim 5, characterized in that: The embedded cavity at the bottom of the chip used by the radio frequency channel is provided with a diamond carrier plate.

10. The method for implementing a multi-channel KU band high duty cycle TR module according to claim 5, characterized in that: The surfaces of the uppermost copper layer, the lowermost copper layer and the copper layer of the stepped mesa of the PCB stacked structure are also plated with a nickel-palladium-gold layer.

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