Wideband large delay numerical control delay module

Abstract

The application discloses a kind of wideband large delay digital control delay module, it is related to the field of radio frequency delay unit.The delay module contains multilayer organic resin substrate, bare chip, passive delay structure, BGA ball grid array and shielding cover plate.Multilayer organic resin substrate is integrated as an entity carrier, slot is provided on the plate, bare chip is placed in slot, and electrical connection is realized with multilayer plate through gold wire bonding.Bare chip includes switch chip, digital control delay chip, attenuator chip, equalizer chip.Passive delay structure is integrated in multilayer board, and it is common with bare chip to constitute radio frequency delay link, which can effectively expand the delay amount of digital control delay chip, realize the large delay amount of module.BGA ball grid array is located below multilayer board, as the external interface of radio frequency delay unit.The application is simple to assemble, short processing cycle, and is suitable for wideband large-scale phased array surface with demand for large delay amount.

Description

Technical Field

[0001] This invention relates to the field of radio frequency delay devices, specifically a broadband long-delay CNC delay module based on the collaborative design of multilayer board and micro-assembly process. Background Technology

[0002] With the rapid development of radar and communication technologies, the design of phased arrays faces greater challenges: on the one hand, to improve detection range and resolution, phased arrays need to have a larger array size; on the other hand, to achieve efficient transmission and processing of broadband signals, wider bandwidth is required. However, the performance of large-scale broadband phased arrays is limited by the core technical bottleneck of the "aperture effect".

[0003] The essence of the aperture effect is that phased arrays achieve beam scanning by applying phase compensation to the signals of each array element through phase shifters. However, the amount of phase compensation by the phase shifters is directly related to the signal frequency. When the operating bandwidth is wide, the wavefronts of signals with different frequency components cannot remain in phase and superimposed in the direction of the target space after compensation by the phase shifters. This leads to problems such as beam pointing deviation, gain reduction, and sidelobe rise. Moreover, the larger the array size, that is, the larger the aperture size, the more significant this effect becomes. To overcome this limitation, a "real time delay" needs to be introduced at the subarray level. By adjusting the physical time delay, it is necessary to ensure that the frequency components within the wide bandwidth are in phase in the target direction, thereby expanding the instantaneous bandwidth of the phased array and improving the large-angle scanning performance.

[0004] Currently, microwave monolithic integrated circuit delay chips are widely used in existing delay solutions due to their ease of mass production and high integration. However, limited by semiconductor processes, such as the chip area and wiring length of GaAs and SiGe, the maximum delay achievable by a single chip is usually not large. According to current market research, the maximum delay is 1575ps in the 0.2~2GHz narrowband range and 630ps in the 1~18GHz broadband range. For large-scale broadband phased arrays, the subarray level needs to achieve nanosecond or even microsecond delays to match the aperture size and scanning angle requirements. Existing monolithic integrated delay chips cannot meet this requirement, becoming a key obstacle restricting the improvement of system performance.

[0005] Therefore, in response to the urgent need for large-delay delay devices in large-scale broadband phased arrays, a numerically controlled delay module that can overcome the limitations of existing monolithic integrated delay device technology is proposed, which has significant technical value and application prospects. Summary of the Invention

[0006] To address the shortcomings of existing delayers in achieving wide bandwidth and large delay, this invention provides a broadband large delay CNC delay module based on multilayer board and micro-assembly process design. Through integrated design and structural optimization, it balances wide bandwidth, large delay, and high reliability.

[0007] The technical solution adopted in this invention is as follows: A broadband long-delay numerically controlled delay module includes a multilayer organic resin substrate, a bare chip, a passive delay structure, a BGA ball grid array, and a shielding cover. The top of the multilayer organic resin substrate has a stepped blind groove; the stepped blind groove includes a first-stage blind groove and a second-stage blind groove, wherein the first-stage blind groove is located on top of the second-stage blind groove. The second-order blind slot is provided with a copper grounding layer and a chip carrier; the bare chip and the copper grounding layer are located on the upper and lower surfaces of the chip carrier, respectively. The passive delay structure is embedded in a multilayer organic resin substrate, and the passive delay structure (3) is connected to the bare chip (2) by gold wire; The shielding cover plate (5) is welded to the upper surface of the multilayer organic resin substrate (1) and located at the top of the stepped blind groove, so that a closed shielding cavity is formed inside the stepped blind groove.

[0008] The BGA ball grid array (4) is soldered to the lower surface of the multilayer organic resin substrate (1), and its radio frequency interface is connected to the bare chip (2) through metallized vias.

[0009] Furthermore, the bare chip (2) is bonded to the upper surface of the chip carrier (8) with conductive adhesive.

[0010] Furthermore, the bare chip (2) includes a numerically controlled delay chip (21), a first equalizer chip (22), a first switch chip (23), a second equalizer chip (24), a fixed attenuator chip (25), and a second switch chip (26). The input terminal of the numerically controlled delay chip (21) is connected to one of the radio frequency interfaces of the BGA ball grid array (4), and the output terminal is connected to the input terminal of the first equalizer chip (22). The output terminal of the first equalizer chip (22) is connected to the moving terminal of the first switch chip. The two stationary terminals of the first switch chip are respectively connected to the fixed attenuator chip (25) and the passive delay structure, wherein the output terminal of the passive delay structure is connected to the input terminal of the second equalizer. The output terminal of the second equalizer and the output terminal of the fixed attenuator are respectively connected to the two stationary terminals of the second switch chip. The moving terminal of the second switch chip is connected to another radio frequency interface of the BGA ball grid array (4) as an output.

[0011] Furthermore, the BGA ball grid array (4) uses lead-free solder balls with a ball pitch of 1mm, and has 2 RF interfaces, 7 low-frequency control interfaces and 2 power interfaces.

[0012] Furthermore, the multilayer organic resin substrate (1) comprises n layers of copper-clad core board and n-1 layers of PP sheet laminated together, where n is a positive integer greater than 2; adjacent copper-clad core boards are separated by PP sheet.

[0013] Furthermore, the passive delay structure (3) includes a metal via and two layers of transmission lines; the two layers of transmission lines are connected through the metal via; the characteristic impedance of the transmission line is 50Ω, and a fixed delay of 640ps is achieved by adjusting the length of the strip line. This delay is twice the delay of 320ps of the highest bit delay state of the numerically controlled delay chip (21); the delay value of the passive delay structure is the sum of the maximum delay of the numerically controlled delay chip and the delay step.

[0014] Furthermore, the radio frequency signal is input through the radio frequency interface of the BGA ball grid array, transmitted to the digitally controlled delay chip through the substrate stripline, and after preliminary delay adjustment and amplitude equalization, it is split into two paths through the first switch: the first signal is transmitted to the stationary terminal of the second switch chip after the amplitude is calibrated by the fixed attenuator chip; the second signal is transmitted to the stationary terminal of the second switch chip after being processed by the passive delay structure and the second equalizer chip; the second switch chip selects the signal according to the control signal input from the low frequency control interface, and finally outputs to the radio frequency interface of the BGA ball grid array (4) through the metallized via.

[0015] Furthermore, the bare chip and the substrate stripline are interconnected by gold wire bonding with a diameter of 25μm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses a small-delay CNC delay bare chip in conjunction with a large-delay passive delay structure to achieve an adjustable delay module that satisfies both small delay step and large delay range. Without changing the delay step of the bare chip, the maximum delay amount can be extended to twice the original amount.

[0017] 2. This invention uses a system-level package with a multilayer organic resin substrate as the carrier and a BGA ball grid array as the external interface, which greatly improves the integration compared to traditional discrete delay modules.

[0018] 3. This invention combines a stepped blind slot and a shielding cover to protect the bare chip and bonding wire, improving module reliability and achieving good shielding of radio frequency signals.

[0019] 4. This invention uses a multilayer organic resin substrate as a carrier, which greatly reduces the processing difficulty and simplifies assembly compared to ceramic substrate carriers, enabling rapid mass production. Attached Figure Description

[0020] Figure 1 This is a cross-sectional structural diagram of an embodiment of the present invention.

[0021] Figure 2 This is a frontal perspective structural diagram of an embodiment of the present invention.

[0022] Figure 3 This is a diagram of the passive delay structure according to an embodiment of the present invention.

[0023] Figure 4 This is a flowchart of the radio frequency signal according to an embodiment of the present invention.

[0024] In the figure: 1 is a multilayer organic resin substrate, 2 is a bare chip, 3 is a passive delay structure, 4 is a BGA ball grid array, 5 is a shielding cover plate, 6 is a first-order blind slot, 7 is a second-order blind slot, 8 is a bare chip carrier, 9 is a metallized via, 10 is a gold wire, 21 is a digitally controlled delay chip, 22 is a first equalizer chip, 23 is a first switch chip, 24 is a second equalizer chip, 25 is a fixed attenuator chip, and 26 is a second switch chip. Detailed Implementation

[0025] A broadband long-delay CNC delay module based on the collaborative design of multilayer board and micro-assembly process includes a multilayer organic resin substrate, bare chip, passive delay structure, BGA ball grid array and shielding cover.

[0026] The multilayer organic resin substrate serves as an integrated carrier for the bare chip and passive delay structure, and includes stepped blind slots. The bare chip comprises a switching chip, a digitally controlled delay chip, an attenuator chip, and an equalizer chip. The bare chip is disposed within the blind slots. The passive delay structure includes a stripline structure and through-layer vias integrated into the inner layers of the multilayer organic resin substrate. The BGA ball grid array is located on the lower surface of the multilayer organic resin substrate, serving as an external interface, including an RF interface and a low-frequency interface. The shielding cover is located directly above the blind slots and overlaps the upper surface of the multilayer organic resin substrate.

[0027] The transmission path of the radio frequency signal is as follows: it is input from the BGA interface, passes through the vias and lines in the multilayer organic resin substrate, and is transmitted to the numerically controlled delay chip. After passing through the first equalizer chip and the first switch chip in sequence, it is divided into two paths. One path passes through the attenuator chip and enters the second switch chip, and the other path passes through the passive delay structure and the second equalizer chip and enters the second switch chip. Finally, it is output from the BGA interface through the vias and lines in the multilayer organic resin substrate.

[0028] The multilayer organic resin substrate is formed by laminating n layers of copper-clad core and n-1 layers of PP sheet, where n is a positive integer greater than 2.

[0029] The stepped blind trench in the multilayer organic resin substrate is a two-stage blind trench, including a first-stage blind trench and a second-stage blind trench. A microstrip line is disposed at the bottom of the first-stage blind trench, and the microstrip line and the bare chip are interconnected by gold wire bonding; the bottom of the second-stage blind trench is a signal ground.

[0030] The bare chip is bonded to the bottom of the second-order blind trench of a multilayer organic resin substrate via a carrier.

[0031] The stripline structure is a serpentine stripline with a characteristic impedance of 50Ω.

[0032] The delay value of the passive delay structure is twice the delay value of the highest bit delay state of the CNC delay chip.

[0033] The following is a more specific embodiment. This embodiment discloses a broadband long-delay CNC delay module based on multilayer board and micro-assembly process, including a multilayer organic resin substrate 1, a bare chip 2, a passive delay structure 3, a BGA ball grid array 4, and a shielding cover plate 5.

[0034] like Figure 1 As shown, the multilayer organic resin substrate 1 is made of 5 layers of copper-clad laminate and 4 layers of PP sheet through a lamination process, with a total of 10 wiring layers and a board thickness of approximately 1.55mm. The substrate surface has stepped blind trenches, including a first-stage blind trench 6 and a second-stage blind trench 7. The first-stage blind trench has a depth of 0.35mm, providing space for bonding the bare chip 2 to the gold wires 10 of the wiring. The second-stage blind trench has a depth of 0.35mm, with a copper ground layer at the bottom and a gold-plated surface. The bare chip 2 is first bonded to the chip carrier 8 with conductive adhesive, and then the two are bonded together to the copper layer at the bottom of the trench. The substrate contains metal vias and transmission lines, which together form a passive delay structure 3. The metal via diameter is 0.2mm, the transmission line width is 0.2mm, and the impedance is matched to 50Ω.

[0035] like Figure 2 As shown, the bare chip 2 includes a digitally controlled delay chip 21, a first equalizer chip 22, a first switch chip 23, a second equalizer chip 24, a fixed attenuator chip 25, and a second switch chip 26. Each chip is fixed to the second-order blind slot 7 with conductive adhesive. The chip pads and substrate traces are interconnected using 25μm diameter gold wire bonding to ensure reliable electrical connections. The digitally controlled delay chip 21 has a frequency range of 1~18GHz, a dynamic delay range of 0-630ps, a step size of 10ps, and a delay bit depth of 6 bits.

[0036] like Figure 3 As shown, the passive delay structure 3 is integrated into the 3rd and 8th layers of the substrate trace layer. It is a serpentine trace structure. The traces between the two layers are interconnected through metal vias. The characteristic impedance of the trace is 50Ω. A fixed delay of 640ps is achieved by adjusting the trace length. This delay is twice the delay of 320ps in the highest bit delay state of the CNC delay chip 21. This structure is connected in series with the CNC delay chip 21 to achieve a total module delay of 1270ps.

[0037] The BGA ball grid array 4 is located on the lower surface of the substrate. It uses lead-free solder balls with a ball pitch of 1mm and a diameter of 0.5mm, totaling 150 solder balls. Among them, there are 2 RF interfaces, 8 low-frequency control interfaces, 2 power interfaces, and the other solder balls are grounded. The BGA ball grid array is connected to the external system through reflow soldering.

[0038] The shielding cover plate 5 is made of copper with a thickness of 0.2mm. It is welded to the upper surface of the substrate to form a closed shielding cavity inside the blind slot, thereby reducing external electromagnetic interference.

[0039] Signal transmission process (combined) Figure 4 Radio frequency signal flowchart): The radio frequency (RF) signal is input through the RF interface of the BGA ball grid array and transmitted to the digitally controlled delay chip via the substrate stripline. After preliminary delay adjustment and amplitude equalization, it is split into two paths: the first path signal is transmitted to the input terminal A of the switching chip after the amplitude is calibrated by the attenuator chip; the second path signal is transmitted to the input terminal B of the switching chip after being processed by the passive delay structure and the equalizer chip. The switching chip selects either the A or B path signal according to the control signal (high or low level) input from the low-frequency control interface, and finally outputs it to the BGA RF interface via the stripline.

[0040] In this embodiment, the detailed working principle of the module is as follows: When the required delay of the system is ≤630ps, the switching chip selects path A. Path A contains only a fixed attenuator, whose delay is negligible. The module uses a numerically controlled delay chip to achieve the delay, with a step of 10ps and a delay range of 0ps~630ps. When the required delay of the system is >630ps, the switching chip selects path B. The passive delay structure in path B has a fixed attenuation of 640ps, which is connected in series with the numerically controlled delay chip (0ps~630ps) to achieve a delay of 640ps~1270ps, with a step of 10ps. Therefore, the maximum delay of the module is 1270ps, with a step of 10ps.

[0041] In this embodiment, the numerically controlled delay module has an insertion loss of ≥-30dB, a delay adjustment accuracy of 10ps, and a maximum delay of 1270ps in the 1-18GHz frequency band, which can basically meet the usage requirements of large-scale broadband phased array systems.

[0042] It should be noted that the above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. For example, the number of layers of the multilayer organic resin substrate can be adjusted according to actual needs, amplifiers can be added in the link to compensate for module losses, and the length of the passive delay structure can be expanded in conjunction with the numerically controlled delay chip to achieve a greater delay. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A broadband long-delay numerically controlled delay module, comprising a multilayer organic resin substrate (1), a bare chip (2), a passive delay structure (3), a BGA ball grid array (4), and a shielding cover plate (5); characterized in that, The top of the multilayer organic resin substrate (1) has a stepped blind groove; the stepped blind groove includes a first-stage blind groove (6) and a second-stage blind groove (7), wherein the first-stage blind groove (6) is located on top of the second-stage blind groove (7). The second-order blind slot (7) is provided with a copper grounding layer and a chip carrier (8); the bare chip (2) and the copper grounding layer are located on the upper and lower surfaces of the chip carrier, respectively; The passive delay structure (3) is embedded in the multilayer organic resin substrate (1), and the passive delay structure (3) is connected to the bare chip (2) by gold wire; The shielding cover plate (5) is welded to the upper surface of the multilayer organic resin substrate (1) and located at the top of the stepped blind groove, so that a closed shielding cavity is formed inside the stepped blind groove. The BGA ball grid array (4) is soldered to the lower surface of the multilayer organic resin substrate (1), and its radio frequency interface is connected to the bare chip (2) through metallized vias.

2. The broadband long-delay CNC delay module according to claim 1, characterized in that, The bare chip (2) is bonded to the upper surface of the chip carrier (8) with conductive adhesive.

3. The broadband long-delay CNC delay module according to claim 1, characterized in that, The bare chip (2) includes a numerically controlled delay chip (21), a first equalizer chip (22), a first switch chip (23), a second equalizer chip (24), a fixed attenuator chip (25), and a second switch chip (26). The input terminal of the numerically controlled delay chip (21) is connected to one of the radio frequency interfaces of the BGA ball grid array (4), and the output terminal is connected to the input terminal of the first equalizer chip (22). The output terminal of the first equalizer chip (22) is connected to the moving terminal of the first switch chip. The two stationary terminals of the first switch chip are respectively connected to the fixed attenuator chip (25) and the passive delay structure. The output terminal of the passive delay structure is connected to the input terminal of the second equalizer. The output terminal of the second equalizer and the output terminal of the fixed attenuator are respectively connected to the two stationary terminals of the second switch chip. The moving terminal of the second switch chip is connected to the other radio frequency interface of the BGA ball grid array (4) as an output.

4. A broadband long-delay CNC delay module according to claim 1, characterized in that, The BGA ball grid array (4) uses lead-free solder balls with a ball pitch of 1mm and has 2 RF interfaces, 8 low-frequency control interfaces and 2 power interfaces.

5. A broadband long-delay CNC delay module according to claim 1, characterized in that, The multilayer organic resin substrate (1) is formed by laminating n layers of copper-clad core and n-1 layers of PP sheet, where n is a positive integer greater than 2; adjacent copper-clad core layers are separated by PP sheet.

6. A broadband long-delay CNC delay module according to claim 1, characterized in that, The passive delay structure (3) includes a metal via and two layers of transmission lines; the two layers of transmission lines are connected by the metal via; the characteristic impedance of the transmission line is 50Ω, and a fixed delay of 640ps is achieved by adjusting the length of the line. This delay is twice the delay of 320ps of the highest bit delay state of the numerically controlled delay chip (21).

7. A broadband long-delay CNC delay module according to claim 1, characterized in that, The radio frequency signal is input through the radio frequency interface of the BGA ball grid array, transmitted to the digitally controlled delay chip through the substrate stripline, and after preliminary delay adjustment and amplitude equalization, it is split into two paths through the first switch: the first signal is transmitted to the stationary terminal of the second switch chip after the amplitude is calibrated by the fixed attenuator chip. The second signal is processed by the passive delay structure and the second equalizer chip and then transmitted to the stationary terminal of the second switch chip. The second switch chip selects the signal according to the control signal input from the low frequency control interface and finally outputs it to the BGA ball grid array (4) RF interface through the metallized via.

8. A broadband long-delay CNC delay module according to claim 7, characterized in that, The bare chip and the substrate stripline are interconnected by gold wire bonding with a diameter of 25μm.

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