Design method of integrated multichannel radio frequency front-end receiver

Abstract

The invention discloses a design method of an integrated multichannel radio frequency front-end receiver. A self-checking source and a 10-channel radio frequency front-end circuit are designed in an integrated manner by using a miniaturized integrated frequency hopping source. And an assembling mode of directly laminating the two-stage modules is adopted, so that the volume and the weight of the radio frequency front-end receiver are effectively reduced. The self-checking power dividing circuit and the control circuit are designed in an integrated mode, the number of needed modules is reduced, the assembling speed is increased, and the assembling efficiency is improved. The application of the packaged power divider effectively reduces the area occupied by the self-checking power dividing circuit, thereby reducing the volume of the multi-channel module. Through various integrated and integrated designs, the weight of the 10-channel front-end assembly integrated with the self-checking source circuit is effectively controlled to be below 2kg, and the size is not greater than 100 * 70 * 36mm < 3 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave communication, especially a design method of an integrated multi-channel RF front-end receiver in the field of reconnaissance. Background Art

[0002] In recent years, military and aerospace electronic equipment has been developing towards being "light, thin, short, and small", and the demand for high density, high integration, and lightweight of its circuit components is becoming more and more urgent. As the core part of the microwave system of electronic reconnaissance equipment, the lightweight and miniaturized design of the integrated multi-channel RF front-end receiver has important significance.

[0003] The lightweight and integrated multi-channel RF front-end receiver, as the most front-end device of the electronic detection system, mainly functions to amplify and filter the detected signals. The traditional design separately designs the RF front-end circuit, self-check power distribution circuit, self-check source circuit, and control circuit into individual modules, and then interconnects them through RF cables and low-frequency connectors, resulting in a heavier overall weight and a larger volume. Summary of the Invention

[0004] The present invention proposes a design method of an integrated multi-channel RF front-end receiver. Without changing the performance of the components, it integrates the 10 RF front-end channels, self-check power distribution circuit, self-check source circuit, and self-check source power processing circuit, and eliminates unnecessary structural parts such as chassis and plug-in boards. By designing the structure, control circuit, and selecting the RF scheme, the volume and weight of the whole machine are reduced.

[0005] The technical solution to realize the present invention is: a design method of an integrated multi-channel RF front-end receiver, characterized by the following steps:

[0006] S1: According to the requirements for the size and function of the receiver in the design requirements of the multi-channel RF front-end receiver, divide the functions of the whole machine to determine the functions of each module.

[0007] S2: According to the function requirements, plan and divide the structure of the whole machine, determine the assembly method between modules, determine the structural dimensions of the modules, and the division of the internal space of the modules.

[0008] S3: According to the plan in S2, design the schematic diagram of the single-channel RF front-end circuit.

[0009] S4: According to the plan in S2, design the self-check source related circuits, specifically including the self-check source boost circuit, self-check source filtering, and signal amplitude conditioning circuit.

[0010] S5: According to the designs in S1-S3, design the 4-channel RF front-end module.

[0011] S6: Design the RF link in the 2-channel RF front-end module according to the designs of S1 - S3.

[0012] S7: Design the self-test source circuit in the 2-channel RF front-end module according to the design plan of S4.

[0013] S8: Design the control circuit on the back of the 2-channel RF front-end module according to the plan in S1.

[0014] S9: Draw the control circuit on the back of the 2-channel RF front-end module according to the design of S8.

[0015] S10: Design the structural shape of each module by considering the cable interconnection between modules based on the circuit diagrams on the front and back of each module.

[0016] S11: Process and manufacture each component according to the designed printed circuit board diagram and structure diagram.

[0017] Compared with the prior art, the significant advantages of the present invention are as follows:

[0018] 1. The overall weight of the receiver designed by the present invention is not greater than 2 kg, and the overall volume is not greater than 100×70×36 mm. 3 .

[0019] 2. The receiver designed by the present invention integrates the self-test source related circuits, including a miniaturized self-test source module, a self-test signal conditioning circuit, and a power voltage step-up and step-down circuit, integrating the functions that originally required 2 - 3 components into 1 component and eliminating the interconnection cables.

[0020] 3. The present invention improves the integration degree of components. By using the RF vertical interconnection technology, the self-test source power splitting circuit that originally needed to be packaged separately using modules is integrated into the front-end channel module, reducing the number and types of modules and interconnection cables, reducing the weight of the entire component, simplifying the assembly process, reducing the processing cost, and improving the production and assembly efficiency.

[0021] 4. The main control circuit is integrated on the back of the 2-channel front-end module, eliminating the separate main control module. The main control circuit distributes the decoded signals to 2 four-channel front-end modules, which can simplify the control circuit on the back of the four-channel front-end module, improve the design efficiency, and reduce the design time.

[0022] 5. By using a surface-mounted packaged power splitter, the area occupied by the L-band self-test power splitting circuit is effectively reduced, thereby reducing the area and weight of the module. Brief Description of the Drawings

[0023] Figure 1 It is the flowchart of the design method of the present invention.

[0024] Figure 2 Schematic diagram of module control relationship in the present invention

[0025] Figure 3 Stacked assembly layout diagram of modules in the present invention

[0026] Figure 4 Schematic diagram of circuit distribution of 2-channel front-end components in the present invention

[0027] Figure 5 Schematic diagram of circuit distribution of 4-channel front-end components in the present invention

[0028] Figure 6 Circuit block diagram of single-channel RF front-end in the present invention

[0029] Figure 7 Signal flow diagram and module cross-sectional view in the module

[0030] Figure 8 Lamination diagram of microwave multilayer board

[0031] Figure 9 Schematic diagram of self-checking source boost circuit in the present invention

[0032] Figure 10 Schematic diagram of self-checking source circuit in the present invention Specific implementation manners

[0033] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Combined with Figures 1 to 10 , the purpose of the present invention is to provide a design method for an integrated multi-channel RF receiver, integrating 10 RF front-ends, a self-checking power splitting circuit, a digital control circuit, and a self-checking source circuit into a component, eliminating unnecessary structural parts such as chassis and plug-in boards, and directly performing a series design on the secondary components to reduce the volume and weight of the entire equipment.

[0035] Next, in combination with the accompanying drawings and embodiments, the implementation of the present invention will be described in detail.

[0036] S1: According to the requirements for the size and function of the receiver in the design requirements of the multi-channel RF front-end receiver, the functions of the whole machine are divided to determine the functions of each module, as follows:[[]]

[0037] The design requirements are that the whole machine needs to meet 10 independent RF front-end channels, amplify, filter, and control the gain of signals, and come with a self-test source and a control circuit. The overall weight is below 2 kg, and the volume is no larger than 100×70×36 mm 3 According to the design requirements, the integrated multi-channel RF front-end receiver is divided into 3 modules, including 2 four-channel front-end modules and 1 two-channel front-end module. The four-channel front-end module completes the RF front-end functions of 4 complete channels, and the two-channel RF front-end includes 2 complete RF channels, a self-test source circuit, and a digital control circuit. The self-test signal generated by the two-channel RF front-end is sent to this module and 2 four-channel RF front-end modules through a cable. The host computer only exchanges control signals and feedback signals with the control circuit of the two-channel RF front-end. The control signal sent by the host computer is input into the two-channel RF front-end for decoding and conversion, and then sent out to control 10 RF channels and the self-test source. The feedback signals of the 10 RF channels and the self-test source are collected in the two-channel RF front-end and then uploaded to the host computer, as Figure 2 shown.

[0038] S2: According to the functional requirements, plan and divide the overall structure of the machine, determine the assembly method between modules, determine the structural dimensions of the modules and the division of the internal space of the modules. The specific steps are as follows:

[0039] The 1 two-channel front-end module and the 2 four-channel front-end modules are installed and assembled in a stacked manner. As Figure 3 shown, the top layer is the two-channel front-end component, and the following two layers are the four-channel front-end components. The self-test signal generated by the two-channel component is input into the four-channel front-end component through a cable; the control instruction sent by the host computer is decoded by the control circuit on the back of the two-channel front-end component and then input into the four-channel front-end component through a low-frequency connector, as Figure 2 .

[0040] The two-channel front-end component consists of 2 exactly the same RF front-end channels and the self-test source related circuits. Among them, the power supply processing part circuit in the self-test source circuit uses SMT technology, the RF conditioning circuit uses micro-assembly technology, and the 2-channel front-end circuits use micro-assembly technology, as Figure 4 . The four-channel front-end component consists of 4 exactly the same RF front-end circuits, as Figure 4 .

[0041] S3: According to the plan in S2, design the schematic diagram of the single-channel RF front-end circuit. The specific steps are as follows:

[0042] According to the task requirements, a single RF front-end channel mainly completes the functions of input channel selection, amplification, filtering, and fault detection of signals. Based on this, select the corresponding devices and draw the principle block diagram of the single-channel RF front-end circuit, as Figure 6 shown.

[0043] S4: According to the plan in S2, design the circuits related to the self-test source, specifically including the self-test source boost circuit, self-test source filtering, and signal amplitude conditioning circuit. The specific steps are as follows:

[0044] Select a miniaturized frequency hopping source module as the core device of the self-test source circuit. The size of this module is 5×12×3mm 3 , and +5V and +18V power supplies are required. Since only +6V power supply is provided externally, a voltage regulator is used to step down +6V to +5V. To reduce the interference of the boost circuit on the power signal, a method of boosting first and then stepping down through an LDO is adopted to isolate the interference in the power signal by using the LDO and reduce the impact of the boost voltage regulator. The +18V power supply is obtained by raising +6V to +20V and then dropping to +18V, as Figure 9 shown. The self-test source filtering and signal amplitude conditioning circuit mainly adjusts the signal amplitude through an attenuator and a filter and filters out redundant harmonic components. To meet the self-test signals required by multiple front-end modules, a power splitter circuit is also needed to split the signal after the self-test source conditioning and filtering circuit.

[0045] S5: According to the designs in S1 - S3, design a 4-channel RF front-end module as follows:

[0046] The front side of the 4-channel RF front-end module has 4 independent RF front-end channels. The RF circuit uses RT5880 board with a thickness of 0.254mm as the substrate for the RF microstrip line. On the back of the module, the self-test power splitter circuit and the control circuit are integrally designed. After the self-test signal is split by the power splitter circuit, it enters the RF link on the front side of the module through an RF insulator, as Figure 7 . A microwave multilayer board is selected as the board for the back circuit. The thickness of this circuit board is 0.8mm. The top layer uses RO4350B with a thickness of 0.254mm as the substrate for the RF microstrip line. Considering cost and processing manufacturing technology, the following uses low-frequency FR4 and corresponding prepreg materials as the support layer of the RF multilayer board, as Figure 8 . Since the L-band frequency is relatively low, the area occupied by the power splitter is inversely proportional to the operating frequency. If a microstrip power splitter is used, it will occupy a large area. Therefore, a packaged integrated power splitter is selected as the power splitter for the self-test power splitter circuit, which can effectively reduce the area occupied by the power splitter circuit and thus reduce the area occupied by the module. The 4-channel RF front-end module receives the control signal from the 2-channel RF front-end module, and converts the received serial code signal to obtain a parallel code signal to control the RF front-end module.

[0047] S6: According to the designs in S1 - S3, design the RF link in the 2-channel RF front-end module as follows:

[0048] The front of the 2-channel RF front-end module has 2 independent RF front-end channels. The self-test power splitting circuit and the control circuit are integrated and designed, and this circuit is placed on the back of the module. The self-test signal is split by the power splitting circuit and then enters the RF link on the front of the module through RF insulators. To reduce the phase difference of the self-test signal in the 2-channel RF front-end module and the 4-channel RF front-end module, the self-test power splitting link in the 2-channel RF front-end module is designed to be the same as that in the 4-channel RF front-end module.

[0049] S7: According to the design plan in S4, design the self-test source circuit in the 2-channel RF front-end module. The specific details are as follows:

[0050] The front of the 2-channel RF front-end module contains circuits related to the self-test source, which uses a separate cavity. The self-test source circuit includes a boost circuit and a self-test source signal conditioning circuit. The self-test source boost circuit uses SMT technology and uses a microwave multi-layer printed board as the carrier. The stack-up design of the microwave multi-layer board is the same as that of the back control board. The self-test source signal conditioning circuit uses micro-assembly technology, and a 0.254mm-thick high-frequency printed board RT5880 is used as the path for microwave signal transmission. The two process circuits in the self-test source related circuit are overlapped through copper foil. The self-test source circuit includes an integrated self-test source module and the corresponding signal conditioning circuit, such as Figure 10 . After the integrated self-test source module receives the external 100MHz reference signal, the generated self-test signal is adjusted in amplitude by a digital controlled attenuator, and the high-order harmonic signals generated by the self-test source module are filtered out by a low-pass filter. After that, multiple identical self-test signals are generated through a power splitter and then sent to each front-end module respectively.

[0051] S8: According to the plan in S1, design the control circuit on the back of the 2-channel RF front-end module. The specific details are as follows:

[0052] The control circuit in the 2-channel RF front-end module is located on the back of the box body and includes an FPGA, differential-to-single-ended, single-ended-to-differential, AD / DA, and serial-to-parallel circuits. Its main function is to decode the control signals sent by the host computer and then forward them to the 2-channel RF front-end and the self-test source of this module, as well as another 2 4-channel RF front-end modules respectively, and encode the fault indication signals fed back by the RF channels and the self-test source and upload them to the host computer. The external control signals receive the control signals from the host computer through the 4 differential control lines CLK+, CLK-, TX+, and TX-, and the differential signals are converted into single-ended signals through a differential-to-single-ended chip. The single-ended-to-differential chip in the 2-channel RF module converts the feedback signals of the entire receiver into differential signals RX+ and RX- and uploads them to the host computer. The control circuit in this module also includes a serial code-to-parallel code circuit, which is used to convert the serial code signals into parallel codes to control the 2-channel RF circuit and the self-test source circuit. For the convenience of subsequent debugging and changing the control program, a debugging interface is left on the side of the 2-channel RF front-end module for program update.

[0053] S9: According to the design in S8, draw the back control circuit of the 2-channel RF front-end module, and proceed to S10;

[0054] S10: Based on the circuit diagrams on the front and back of each module and considering the cable interconnection between modules, design the structural shape of each module.

[0055] S11: Process and manufacture each component according to the designed printed circuit board diagram and structure diagram.

Claims

1. A design method for an integrated multi-channel RF front-end receiver, characterized in that, The steps are as follows: S1: According to the requirements for the size and functions of the multi-channel RF front-end receiver in the design requirements, divide the functions of the whole machine and determine the functions of each module. S2: According to the functional requirements, plan and divide the structure of the whole machine, determine the assembly method between modules, determine the structural dimensions of the modules and the division of the internal space of the modules. S3: Design the schematic diagram of the single-channel RF front-end circuit according to the plan in S2. S4: Design the circuits related to the self-test source according to the plan in S2, specifically including the self-test source boost circuit, self-test source filtering and signal amplitude conditioning circuit. S5: Design the 4-channel RF front-end module according to the designs in S1 - S3. S6: Design the RF link in the 2-channel RF front-end module according to the designs in S1 - S3. S7: Design the self-test source circuit in the 2-channel RF front-end module according to the design in S4. S8: Design the control circuit on the back of the 2-channel RF front-end module according to the plan in S1. S9: Draw the control circuit on the back of the 2-channel RF front-end module according to the design in S8. S10: Design the structural shape of each module by considering the cable interconnection between modules according to the circuit diagrams on the front and back of each module. S11: Process and manufacture each component according to the designed printed circuit board diagram and structure diagram.

2. The design method of the integrated multi-channel RF front-end receiver according to claim 1, wherein In S1, according to the requirements for the size and functions of the multi-channel RF front-end receiver in the design requirements, divide the functions of the whole machine and determine the functions of each module, specifically as follows: The design requirements state that the whole machine needs to meet 10 independent RF front-end channels, amplify, filter, and perform gain control on signals, come with a self-test source and control circuit, have an overall weight of less than 2 kg, and a volume not exceeding 100×70×36 mm 3 ; According to the design requirements, the integrated multi-channel RF front-end receiver is divided into 3 modules, including 2 four-channel front-end modules and 1 two-channel front-end module; The 4-channel front-end module completes the RF front-end functions of 4 complete channels. The 2-channel RF front-end includes 2 complete RF channels, a self-test source circuit, and a digital control circuit. The self-test signal generated by the 2-channel RF front-end is sent to this module and 2 4-channel RF front-end modules through cables. The host computer only exchanges control signals and feedback signals with the control circuit of the 2-channel RF front-end. The control signal sent by the host computer is input into the 2-channel RF front-end for decoding and conversion, and then sent out to control 10 RF channels and the self-test source. The feedback signals of the 10 RF channels and the self-test source are collected in the 2-channel RF front-end and then uploaded to the host computer.

3. The design method of the integrated multi-channel RF front-end receiver according to claim 1, wherein, In S2, according to the functional requirements, plan and divide the structure of the whole machine, determine the assembly method between modules, determine the structural dimensions of the modules and the division of the internal space of the modules. The steps are as follows: One 2-channel front-end module and two 4-channel front-end modules are assembled in a stacked manner. The top layer is the 2-channel front-end component, and the following two layers are 4-channel front-end components. The self-test signal generated by the 2-channel component is input into the 4-channel front-end component through a cable. The control instruction sent by the host computer is decoded by the control circuit on the back of the 2-channel front-end component and then input into the 4-channel front-end component through a low-frequency connector. The 2-channel front-end component consists of 2 exactly the same RF front-end channels and circuits related to the self-test source. Among them, the power processing part circuit in the self-test source circuit uses SMT technology, the RF conditioning circuit uses micro-assembly technology, and the 2-channel front-end circuits use micro-assembly technology. The 4-channel front-end component consists of 4 exactly the same RF front-end circuits.

4. The design method of the integrated multi-channel RF front-end receiver according to claim 1, characterized in that In S3, according to the plan in S2, design the schematic diagram of the single-channel RF front-end circuit. The steps are as follows: According to the task requirements, a single RF front-end channel mainly completes the functions of signal input channel selection, amplification, filtering, and fault detection. Based on this, select the corresponding devices and draw the principle block diagram of the single-channel RF front-end circuit.

5. The design method of the integrated multi-channel RF front-end receiver according to claim 1, characterized in that In S4, according to the plan in S2, design the self-test source related circuits, specifically including the self-test source boost circuit, self-test source filtering, and signal amplitude conditioning circuit. The steps are as follows: Select a miniaturized frequency hopping source module as the core device of the self-test source circuit. The size of this module is 5×12×3mm 3 , and +5V and +18V power supplies need to be provided. Since only +6V power supply is provided externally, a voltage regulator is used to step down +6V to +5V. In order to reduce the interference of the boost circuit on the power signal, the method of boosting first and then stepping down through an LDO is adopted to isolate the interference in the power signal by using the LDO and reduce the influence of the boost voltage regulator. The +18V power supply is obtained by raising +6V to +20V and then dropping to +18V. The self-test source filtering and signal amplitude conditioning circuit mainly adjusts the amplitude of the signal through an attenuator and a filter and filters out redundant harmonic components. In order to meet the self-test signals required by multiple front-end modules, a power splitter circuit is also needed to split the signal after the self-test source conditioning and filtering circuit.

6. The design method of the integrated multi-channel RF front-end receiver according to claim 1, characterized in that In S5, according to the designs in S1 - S3, design the 4-channel RF front-end module as follows: The front side of the 4-channel RF front-end module has 4 independent RF front-end channels. The RF circuit uses RT5880 board with a thickness of 0.254 mm as the substrate of the RF microstrip line. On the back of the module, the self-test power splitter circuit and the control circuit are integrated. The self-test signal is split by the power splitter circuit and then enters the RF link on the front side of the module through the RF insulator. Microwave multilayer board is selected as the board material for the back circuit. The thickness of this circuit board is 0.8 mm. The top layer uses RF material RO4350B with a thickness of 0.254 mm as the substrate of the RF microstrip line. Considering cost and processing manufacturing process, the following uses low-frequency FR4 and corresponding prepreg materials as the support layer of the RF multilayer board. Since the L-band frequency is relatively low, the area occupied by the power splitter is inversely proportional to the operating frequency. If a microstrip power splitter is used, it will occupy a large area. Therefore, a packaged integrated power splitter is selected as the power splitter for the self-test power splitter circuit, which can effectively reduce the area occupied by the power splitter circuit, thereby reducing the area occupied by the module. The 4-channel RF front-end module receives the control signal from the 2-channel RF front-end module, and converts the received serial code signal into a parallel code signal to control the RF front-end module.

7. The design method of the integrated multi-channel RF front-end receiver according to claim 1, characterized in that In S6, according to the designs in S1 - S3, design the RF link in the 2-channel RF front-end module as follows: The front side of the 2-channel RF front-end module has 2 independent RF front-end channels. The self-test power splitter circuit and the control circuit are integrated, and this circuit is placed on the back of the module. The self-test signal is split by the power splitter circuit and then enters the RF link on the front side of the module through the RF insulator. In order to reduce the phase difference of the self-test signal in the 2-channel RF front-end module and the 4-channel RF front-end module, the self-test power splitter link in the 2-channel RF front-end module is designed to be the same as that in the 4-channel RF front-end module.

8. The design method of the integrated multi-channel RF front-end receiver according to claim 1, characterized in that, In S7, according to the design plan in S4, design the self-test source circuit in the 2-channel RF front-end module as follows: The front side of the 2-channel RF front-end module contains self-test source related circuits, which adopt a separate cavity. The self-test source circuit includes a boost circuit and a self-test source signal conditioning circuit. The self-test source boost circuit adopts SMT technology and uses a microwave multi-layer printed board as the carrier. The stack-up design of the microwave multi-layer board is the same as that of the back control board. The self-test source signal conditioning circuit adopts micro-assembly technology, and a 0.254-mm-thick high-frequency printed board RT5880 is used as the path for microwave signal transmission. The two process circuits in the self-test source related circuit are overlapped through copper foil. The self-test source circuit includes an integrated self-test source module and the corresponding signal conditioning circuit. After receiving the external 100-MHz reference signal, the self-test signal generated by the integrated self-test source module is adjusted in amplitude by a digital attenuator, and the high-order harmonic signals generated by the self-test source module are filtered out by a low-pass filter. After that, through a power divider, multiple identical self-test signals are generated and then sent to each front-end module respectively.

9. The design method of the integrated multi-channel RF front-end receiver according to claim 1, characterized in that In S8, according to the plan in S1, a control circuit is designed on the back of the 2-channel RF front-end module, specifically as follows: The control circuit in the 2-channel RF front-end module is located on the back of the box and includes an FPGA, differential-to-single-ended, single-ended-to-differential, AD / DA, and serial-to-parallel circuits. Its main function is to decode the control signals sent by the host computer and then forward them to the 2-channel RF front-end and self-test source of this module, as well as another two 4-channel RF front-end modules respectively, and encode the fault indication signals fed back by the RF channels and self-test source and upload them to the host computer. The external control signals receive the control signals from the host computer through the four differential control lines CLK+, CLK-, TX+, and TX-, and the differential signals are converted into single-ended signals through a differential-to-single-ended chip. The single-ended-to-differential chip in the 2-channel RF module converts the feedback signals of the entire receiver into differential signals RX+ and RX- and uploads them to the host computer. The control circuit in this module also includes a serial code-to-parallel code circuit, which is used to convert the serial code signals into parallel codes to control the 2-channel RF circuit and the self-test source circuit. For the convenience of subsequent debugging and changing the control program, a debugging interface is reserved on the side of the 2-channel RF front-end module for program update.

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