Light receiving assembly

Abstract

The invention, which belongs to the technical field of optical communication, discloses an optical receiving assembly comprising a circuit board, an array waveguide grating, a photoelectric detector, a trans-impedance amplifier and a substrate. The circuit board is provided with a first conductive pattern, and the first conductive pattern comprises a plurality of pairs of differential signal lines and a plurality of grounding lines of a receiving end. A second conductive pattern is arranged on the substrate, the second conductive pattern comprises a plurality of pairs of fan-out differential traces and a plurality of fan-out ground wires, the fan-out ground wires are fan-out side by side, a pair of fan-out differential traces is arranged between every two adjacent fan-out ground wires, and the trans-impedance amplifier is electrically connected with the circuit board through the second conductive pattern. The substrate is added between the trans-impedance amplifier and the differential signal lines of the circuit board, and the fan-out differential traces are arranged on the substrate so as to be matched with the channel spacing of the differential signal lines with larger channel spacing on the circuit board, so that the length of the bonding wire can be shortened, the signal crosstalk is further reduced, and the high-frequency performance is optimized.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, specifically to an optical receiving component. Background Technology

[0002] In the field of high-speed optical communication in data centers, optical modules need to meet the requirements of high-capacity and low-cost transmission. Therefore, the optical receiving components at the receiving end often employ wavelength demultiplexing schemes to separate and convert multi-wavelength optical signals. Wavelength demultiplexing devices for optical receiving components are mainly divided into two categories: Z-block filter structures and arrayed waveguide gratings (AWGs). Due to their lower cost and smaller size, AWGs have become the mainstream choice for reducing costs and improving integration in current optical module receivers.

[0003] Furthermore, the transimpedance amplifier and the circuit board of the optical receiver are typically directly connected via bonding wires. When there are many channels, the channel arrangement becomes denser, and high-speed electrical signals are susceptible to crosstalk from adjacent channels during transmission, further affecting the signal reception quality of the optical receiver. Summary of the Invention

[0004] An optical receiving component is provided, which aims to improve the high-frequency performance of signal transmission of the optical receiving component and reduce channel crosstalk.

[0005] Embodiments of this application provide an optical receiving component, including: A circuit board having a first conductive pattern, the first conductive pattern including multiple pairs of differential signal lines and multiple ground lines at the receiving end, the multiple ground lines being arranged in parallel, and a pair of differential signal lines being arranged between two adjacent ground lines; An arrayed waveguide grating is used to receive optical signals and demultiplex the optical signals before outputting them. A photodetector is used to receive the optical signal output by the arrayed waveguide grating and convert it into an electrical signal for output. A transimpedance amplifier is electrically connected to the photodetector and the circuit board respectively. The transimpedance amplifier is used to receive the electrical signal output by the photodetector, process the electrical signal and output it. The signal output terminal of the transimpedance amplifier includes multiple pairs of differential signal terminals and multiple ground terminals. The multiple ground terminals are arranged side by side, and a pair of differential signal terminals is arranged between two adjacent ground terminals. A substrate is provided on the substrate, the second conductive pattern including multiple pairs of fan-out differential traces and multiple fan-out ground lines, the multiple fan-out ground lines are fan-out side by side, and a pair of fan-out differential traces are provided between two adjacent fan-out ground lines, the transimpedance amplifier is electrically connected to the circuit board through the second conductive pattern; The fan-out differential trace is located between the signal output terminal of the transimpedance amplifier and the differential signal line of the first conductive pattern. The fan-out differential trace includes a first end and a second end. The first end faces the transimpedance amplifier and is electrically connected to the corresponding differential signal terminal. The second end faces the differential signal line of the first conductive pattern and is electrically connected to the corresponding differential signal line. The distance between the first ends of any two adjacent pairs of fan-out differential traces is smaller than the distance between the second ends. One end of the fan-out ground wire is electrically connected to the ground terminal of the corresponding transimpedance amplifier, and the other end is electrically connected to the ground wire of the corresponding first conductive pattern.

[0006] In one embodiment of this application, the spacing between the first ends of two adjacent pairs of fan-out differential traces is 0.3mm to 0.4mm, and the spacing between the second ends of two adjacent pairs of fan-out differential traces is 0.4mm to 0.6mm.

[0007] In one embodiment of this application, a ground reference layer is provided on the bottom surface of the substrate facing away from the second conductive pattern, and a ground return via is provided between the fan-out ground line and the ground reference layer, the ground return via being electrically connected to the ground reference layer and the fan-out ground line.

[0008] In one embodiment of this application, the optical receiving component further includes bonding wires, which include a first bonding wire, a second bonding wire, and a third bonding wire. The photodetector is electrically connected to the transimpedance amplifier via the first bonding wire, the transimpedance amplifier is electrically connected to the second conductive pattern via the second bonding wire, and the second conductive pattern is electrically connected to the first conductive pattern via the third bonding wire.

[0009] In one embodiment of this application, the length of the bonding wire is less than or equal to 0.55 mm.

[0010] In one embodiment of this application, the substrate is disposed on the circuit board, and the arrayed waveguide grating, the photodetector and the transimpedance amplifier are all disposed on the substrate.

[0011] In one embodiment of this application, the substrate is a single pad, and the arrayed waveguide grating, the photodetector, and the transimpedance amplifier are arranged sequentially on the single pad along the signal transmission direction.

[0012] In one embodiment of this application, the substrate includes a first pad and a second pad, the arrayed waveguide grating and the photodetector are disposed on the first pad, and the first pad is a bare block structure; the transimpedance amplifier is disposed on the second pad, and the second conductive pattern is disposed on the surface of the second pad.

[0013] In one embodiment of this application, the second conductive pattern further includes a device pad, on which the transimpedance amplifier is soldered, and the device pad is connected to the fan-out ground line.

[0014] In one embodiment of this application, the second conductive pattern further includes a filter capacitor, which is electrically connected to the circuit board and the transimpedance amplifier, respectively.

[0015] In one embodiment of this application, the coefficient of thermal expansion of the substrate is smaller than that of the circuit board; The substrate is any one of a silicon substrate, a ceramic substrate, or a glass substrate.

[0016] The beneficial effects of this application are as follows: This application uses GSSG differential signal lines in the optical receiving component to improve the inter-channel isolation of the multi-channel high-speed optical module and reduce signal crosstalk between channels; at the same time, a substrate is added between the transimpedance amplifier and the differential signal lines of the circuit board, and fan-out differential traces are set on the substrate. The differential signal terminals with smaller channel spacing on the transimpedance amplifier can be fanned out through the fan-out differential traces to match the channel spacing of the differential signal lines with larger channel spacing on the circuit board, thereby shortening the bonding wire length, further reducing signal crosstalk, and optimizing high-frequency performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is one of the schematic diagrams of the optical receiving component structure provided in the embodiments of this application; Figure 2 This is one of the schematic diagrams of the fan-out traces provided in the embodiments of this application; Figure 3 This is a schematic diagram of the bottom surface of the substrate provided in an embodiment of this application; Figure 4 This is the second schematic diagram of the optical receiving component structure provided in the embodiments of this application; Figure 5 This is the second schematic diagram of the fan-out trace provided in the embodiments of this application.

[0019] Explanation of reference numerals in the attached figures: 1. Circuit board; 11. First conductive pattern; 111. Differential signal line; 112. Ground line; 2. Substrate; 21. Second conductive pattern; 211. Fan-out differential trace; 2111. First terminal; 2112. Second terminal; 212. Fan-out ground line; 213. Filter capacitor; 22. Ground return via; 23. Ground reference layer; 24. Device pad; 3. Arrayed waveguide grating; 4. Photodetector; 5. Transimpedance amplifier; 61. First pad; 62. Second pad; 71. First bonding wire; 72. Second bonding wire; 73. Third bonding wire. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In high-speed optical modules, as module speeds increase, the number of integrated signal channels also increases. However, the external size of optical modules is limited by standards, and internal space is limited. To integrate more optical paths, the size of arrayed waveguide gratings, photodetectors, and transimpedance amplifiers needs to be reduced. For example, in an eight-channel optical module, two smaller transimpedance amplifiers can be used to achieve two sets of four-channel signal processing. This also results in very small spacing between the channel terminals of the transimpedance amplifiers. Furthermore, the size of the circuit board is also limited by the internal space of the module and cannot be made large. The more channels integrated on the circuit board, the smaller the spacing between channels, making it easier for signal crosstalk to occur between adjacent channels, thus hindering the improvement of transmission rates.

[0023] Embodiments of this application provide an optical receiving component, such as... Figure 1 As shown, it includes a circuit board 1, an arrayed waveguide grating 3, and a photodetector 4.

[0024] The arrayed waveguide grating 3 receives externally input optical signals and demultiplexes them before outputting them. The photodetector 4 is positioned corresponding to the signal output surface of the arrayed waveguide grating 3, receiving the demultiplexed optical signals and converting them into electrical signals via the photoelectric effect. The transimpedance amplifier 5 is electrically connected to both the photodetector 4 and the circuit board 1. One end of the transimpedance amplifier 5 receives the electrical signal output from the photodetector 4, processes it through its internal circuitry, and then outputs the processed electrical signal to the circuit board 1 from the other end. The circuit board 1 then transmits and outputs the received electrical signal.

[0025] In this embodiment, the number of photodetectors 4 is the same as the number of channels of the arrayed waveguide grating 3, and each photodetector 4 is used to receive the optical signal demultiplexed from one channel of the arrayed waveguide grating 3. Multiple photodetectors 4 can be provided in the form of a detector array chip, or multiple discrete photodetectors 4 arranged side-by-side.

[0026] To address the signal crosstalk problem during multi-channel parallel transmission, the optical receiving component provided in this application employs a ground-signal-signal-ground (GSSG) differential signal transmission structure to transmit electrical signals.

[0027] Specifically, the optical receiving component provided in this application has a first conductive pattern 11 on its circuit board 1. The first conductive pattern 11 includes multiple pairs of differential signal lines 111 and multiple ground lines 112. The multiple ground lines 112 are arranged in parallel, and a pair of differential signal lines 111 is set between every two adjacent ground lines 112 to form a GSSG transmission structure. The optical receiving component transmits electrical signals through the differential signal lines 111, which can effectively improve high-frequency performance and help increase the single-channel transmission rate. In addition, the ground lines 112 provide shielding for the differential signal lines 111, improving the signal isolation between channels, thereby reducing signal crosstalk between channels and reducing the impact of external electromagnetic interference on the signal.

[0028] The terminal layout of the signal output terminal of the transimpedance amplifier 5 corresponds to the first conductive pattern 11 of the circuit board 1. The signal output terminal of the transimpedance amplifier 5 includes multiple pairs of differential signal terminals and multiple ground terminals. The multiple ground terminals are arranged side by side, and a pair of differential signal terminals is arranged between two adjacent ground terminals. Each differential signal output by the transimpedance amplifier 5 is shielded and protected by the ground terminals to avoid crosstalk during the output process.

[0029] To integrate more signal channels, the differential signal terminals of the transimpedance amplifier 5 have a smaller spacing. However, due to limitations in manufacturing processes, wiring space, and external interface compatibility requirements, the size and spacing of the differential signal lines 111 of the first conductive pattern 11 of the circuit board 1 cannot match the size and spacing of the terminals of the transimpedance amplifier 5. If bonding wires are directly used to connect the transimpedance amplifier 5 and the circuit board 1, the bonding wires at the channel edges need to be quite long, even exceeding 0.85mm, because the size and spacing of the terminals of the transimpedance amplifier 5 and the differential signal lines 111 of the circuit board 1 are incompatible. Long bonding wires introduce significant parasitic inductance and capacitance. In high-frequency signal transmission scenarios, parasitic parameters can lead to severe signal attenuation and phase shift. Furthermore, adjacent bonding wires are prone to crossing or running parallel in close proximity, severely affecting signal transmission quality. In addition, because the size and spacing of the differential signal lines 111 of the circuit board 1 are larger than the terminals of the transimpedance amplifier 5, the GSSG lines of the circuit board 1 cannot be arranged around the terminals of the transimpedance amplifier 5.

[0030] In embodiments of this application, a GSSG differential fan-out line is provided between the transimpedance amplifier 5 and the first conductive pattern 11 of the circuit board 1 to fan out the terminals of the transimpedance amplifier 5, so as to match the differential signal line 111 of the circuit board 1. Specifically, as Figure 2 As shown, the optical receiving assembly also includes a substrate 2, on which a second conductive pattern 21 is provided. The second conductive pattern 21 provides GSSG differential fan-out lines between the transimpedance amplifier 5 and the first conductive pattern 11 of the circuit board 1. Specifically, the second conductive pattern 21 includes multiple pairs of fan-out differential traces 211 and multiple fan-out ground lines 212. The multiple fan-out ground lines 212 are fanned out side by side, and a pair of fan-out differential traces 211 are arranged between two adjacent fan-out ground lines 212. The transimpedance amplifier 5 is electrically connected to the circuit board 1 through the second conductive pattern 21. The electrical signal output by the transimpedance amplifier 5 is first transmitted to the second conductive pattern 21 of the substrate 2, and after being fanned out by the second conductive pattern 21, it is transmitted to the circuit board 1.

[0031] The differential fan-out line is provided by a second conductive pattern 21 disposed on the substrate 2. It is compatible with semiconductor manufacturing processes, has high processing precision, and can be processed to produce differential fan-out lines whose size and spacing match the terminals of the transimpedance amplifier 5. This solves the problem caused by the mismatch between the size and spacing of the differential signal lines 111 on the circuit board 1 and the terminals of the transimpedance amplifier 5.

[0032] Specifically, in some embodiments, the fan-out differential trace 211 includes a first end 2111 and a second end 2112 facing each other. The first end 2111 faces the transimpedance amplifier 5 and is electrically connected to the corresponding differential signal terminal, while the second end 2112 faces the differential signal line 111 of the first conductive pattern 11 and is electrically connected to the corresponding differential signal line 111. The spacing between the first ends 2111 of any two adjacent pairs of fan-out differential traces 211 is smaller than the spacing between the second ends 2112.

[0033] In this application, the first end 2111 of the fan-out differential trace 211 matches the terminal spacing of the output terminal of the transimpedance amplifier 5. In some embodiments, the spacing between the first ends 2111 of two adjacent pairs of fan-out differential traces 211 is 0.3mm to 0.4mm, for example, it can be 0.3mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm, 0.4mm, etc. This can greatly shorten the length of the second bonding wire 72, and in this application, the length of the second bonding wire 72 can be controlled within 0.55mm.

[0034] The second end 2112 of the fan-out differential trace 211 matches the terminal spacing of the first conductive pattern 11. In some embodiments, the spacing of the second end 2112 between two adjacent pairs of fan-out differential traces 211 is 0.4mm to 0.6mm, for example, it can be 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, 0.52mm, 0.54mm, 0.56mm, 0.58mm, 0.6mm, etc. This can greatly shorten the length of the third bonding wire 73, and in this application, the length of the third bonding wire 73 can be controlled within 0.55mm.

[0035] In some embodiments, the optical receiving component further includes bonding wires, including a first bonding wire 71, a second bonding wire 72, and a third bonding wire 73. The photodetector 4 is electrically connected to the transimpedance amplifier 5 through the first bonding wire 71, the transimpedance amplifier 5 is electrically connected to the second conductive pattern 21 through the second bonding wire 72, and the second conductive pattern 21 is electrically connected to the first conductive pattern 11 through the third bonding wire 73.

[0036] According to the above embodiment, the first end 2111 of the differential fan-out line can be evenly arranged around the terminals of the transimpedance amplifier 5, while the spacing of the second end 2112 is matched with the spacing of the differential signal lines 111 on the circuit board 1 through the fan-out trace. In this way, the bond wire lengths of each channel between the transimpedance amplifier 5 and the differential fan-out line are relatively similar, and the bond wire lengths of each channel between the differential fan-out line and the differential signal lines 111 on the circuit board 1 are also relatively similar. Furthermore, the bond wire length can be shortened, thereby reducing parasitic inductance and capacitance, reducing signal attenuation, and reducing signal phase shift, ensuring the quality and timing consistency of multi-channel signals. Moreover, the combination of the fan-out differential trace 211 and the fan-out ground line 212 to form a GSSG structure can further suppress signal crosstalk.

[0037] In some embodiments, the fan-out ground line 212 is widened smoothly and gradually from the first end 2111 to the second end 2112 so that a stable gap is maintained between the fan-out ground line 212 and the two pairs of fan-out differential traces 211 on the adjacent sides.

[0038] In some embodiments, such as Figure 3 As shown, a ground reference layer 23 is provided on the bottom surface of the substrate 2 facing away from the second conductive pattern 21. Meanwhile, a ground return via 22 is also formed between the fan-out ground line 212 and the ground reference layer 23. This ground return via 22 electrically connects the ground reference layer 23 and the fan-out ground line 212, and is used to optimize the return path and suppress signal crosstalk on the fan-out differential trace 211.

[0039] Specifically, the ground reference layer 23 is a large-area metal layer, such as a copper layer. It covers the bottom surface of the substrate 2 and provides a potential reference surface for the fan-out differential trace 211 and the fan-out ground line 212. When the fan-out differential trace 211 transmits high-speed signals, the ground reference layer 23 can absorb electromagnetic interference from the surrounding environment, and at the same time suppress the electromagnetic energy radiated outward by the fan-out differential trace 211.

[0040] The ground return via 22 electrically connects the fan-out ground line 212 and the ground reference layer 23. In high-speed signal transmission, the return current of the signal requires a low-impedance path. The direct connection between the fan-out ground line 212 and the ground reference layer 23 via the ground return via 22 reduces the impedance of the return path and optimizes it. Between adjacent fan-out differential traces 211, the presence of the ground return via 22 and the ground reference layer 23 significantly weakens the electromagnetic coupling path, thus suppressing crosstalk.

[0041] In some embodiments, the substrate 2 is disposed on the circuit board 1, such as by adhesive bonding to the surface of the circuit board 1. The arrayed waveguide grating 3, photodetector 4, and transimpedance amplifier 5 are all disposed on the substrate 2. The coefficient of thermal expansion of the substrate 2 is less than that of the circuit board 1, resulting in a significantly smaller deformation of the substrate 2 during temperature fluctuations compared to the deformation of the circuit board 1. The expansion and contraction deformation of the circuit board 1 is isolated by the substrate 2 and cannot be transmitted to the devices, effectively preventing positional displacement of the devices due to deformation of the circuit board 1.

[0042] Specifically, in this embodiment, the coefficient of thermal expansion of substrate 2 is close to that of arrayed waveguide grating 3. For example, substrate 2 can be a silicon substrate. In other embodiments, substrate 2 can also be a glass substrate or a ceramic substrate, etc.

[0043] In this embodiment, the second conductive pattern 21 also includes a device pad 24, on which the transimpedance amplifier 5 is soldered and connected to the fan-out ground line 212.

[0044] The device pad 24 is directly electrically connected to the fan-out ground line 212, forming a grounding path from the fan-out ground line 212 to the transimpedance amplifier 5. When the transimpedance amplifier 5 is soldered onto the device pad 24, it not only achieves mechanical fixation between the transimpedance amplifier 5 and the substrate 2, but also grounds the transimpedance amplifier 5 through the device pad 24, providing a ground reference for the transimpedance amplifier 5 and avoiding noise interference caused by poor grounding of the transimpedance amplifier 5.

[0045] In some embodiments, the substrate 2 is a single pad, on which the arrayed waveguide grating 3, photodetector 4, and transimpedance amplifier 5 are arranged sequentially along the signal transmission direction. In this embodiment, the photodetector 4 and the transimpedance amplifier 5, and the transimpedance amplifier 5 and the second conductive pattern 21, can be electrically connected via bonding wires. In other embodiments, the photodetector 4 can be a back-mounted detector, soldered to the substrate 2 via pins located on the back of the photosensitive surface. The transimpedance amplifier 5 is also soldered to the substrate 2 via a flip-chip process. The photodetector 4 and the transimpedance amplifier 5, and the transimpedance amplifier 5 and the second conductive pattern 21, can be electrically connected via conductive traces on the surface of the substrate 2, eliminating the need for bonding wires. This further optimizes the path between the transimpedance amplifier 5 and the fan-out differential trace 211 and the fan-out ground line 212, improving high-frequency performance.

[0046] In some embodiments, such as Figure 4 As shown, substrate 2 includes a first pad 61 and a second pad 62. An arrayed waveguide grating 3 and a photodetector 4 are disposed on the first pad 61. The first pad 61 is a bare block structure without any conductive patterns, metallization layers, or openings. A transimpedance amplifier 5 is disposed on the second pad 62, and a second conductive pattern 21 is disposed on the surface of the second pad 62.

[0047] The output end of the arrayed waveguide grating 3 is precisely aligned with the photosensitive surface of the photodetector 4 on the first pad 61. The optical signal is directly transmitted from the arrayed waveguide grating 3 to the photodetector 4, eliminating the need for a coupling lens and reducing costs. The photodetector 4 is electrically connected to the transimpedance amplifier 5 on the second pad 62 via a first bonding wire 71. The heights of the first pad 61 and the second pad 62 are matched to reduce the height difference between the pads on the surfaces of the photodetector 4 and the transimpedance amplifier 5, shortening the length of the first bonding wire 71 to 0.35 mm. The reduced length of the first bonding wire 71 significantly reduces parasitic inductance and capacitance, preventing phase shift and attenuation of high-frequency signals during transmission and significantly reducing signal crosstalk between adjacent channels.

[0048] The second conductive pattern 21 and the ground return via 22 need to be fabricated on the pad through multiple processes such as surface coating, photolithography, etching vias, and metallizing vias. The substrate 2 is divided into two parts: a first pad 61 and a second pad 62. The second conductive pattern 21 and the return vias only need to be fabricated on the second pad 62. The first pad 61 only needs to support optical devices and does not require circuitry, therefore it can be configured as a bare block structure. The bare block structure eliminates all patterning processes, saving costs. Furthermore, compared to the entire substrate 2, the first pad 61 and the second pad 62 are smaller, improving the utilization rate of the substrate 2 and further reducing its cost.

[0049] Furthermore, if the arrayed waveguide grating 3 or photodetector 4 needs to be replaced, only the first pad 61 needs to be adjusted; the second conductive pattern 21 of the second pad 62 does not need to be changed. Similarly, when replacing the transimpedance amplifier 5, only the second conductive pattern 21 of the second pad 62 needs to be adjusted; the first pad 61 can remain unchanged. This improves the compatibility of the substrate 2.

[0050] This application divides the substrate 2 into two independent units: a first pad 61 and a second pad 62. The first pad 61 is a bare block structure, while the second pad 62 has a second conductive pattern 21. Compared to a single pad structure, this reduces costs and improves the compatibility of the substrate 2.

[0051] In some embodiments, such as Figure 5 As shown, the second conductive pattern 21 also includes a filter capacitor 213, which is disposed on the second pad 62 and is electrically connected to the transimpedance amplifier 5.

[0052] The filter capacitor 213 is directly integrated onto the surface of the second pad 62, which has the second conductive pattern 21. One end of the filter capacitor 213 is electrically connected to the transimpedance amplifier 5, and the other end is connected to the circuit board 1. In some embodiments, the transimpedance amplifier 5, as a high-precision chip, has high requirements for the stability of the power supply. When the optical receiving component is working, there will be interference signals such as high-frequency ripple and switching noise in the power supply line of the circuit board 1. The interference signals will enter the transimpedance amplifier 5 through the power supply line, causing distortion of the amplified electrical signal. The filter capacitor 213 is connected to both the circuit board 1 and the transimpedance amplifier 5, which can bypass the high-frequency interference signals in the power supply to ground, providing a clean power supply voltage for the transimpedance amplifier 5.

[0053] In the arrayed waveguide grating 3 scheme, the arrayed waveguide grating 3, photodetector 4, and transimpedance amplifier 5 are all bonded to the circuit board 1 with adhesive. Since the circuit board 1 is prone to deformation when the temperature changes, and the thermal expansion coefficients of the adhesive, arrayed waveguide grating 3, and photodetector 4 are quite different, temperature fluctuations will further aggravate the relative positional misalignment between the components, resulting in a decrease in optical path alignment accuracy.

[0054] This application sets a substrate 2 on a circuit board 1, and places the arrayed waveguide grating 3 and the photodetector 4 on the same surface of the substrate 2 facing away from the circuit board 1. This isolates the circuit board 1 from the deformation caused by temperature, reduces the relative positional shift between the two caused by temperature changes, and sets patterned fan-out traces on the substrate 2 so that the output of the transimpedance amplifier 5 can be connected to the receiving part of the circuit board 1 through the fan-out traces. This reduces direct connection interference between the transimpedance amplifier 5 and the circuit board 1, suppresses signal crosstalk, and improves signal reception quality.

[0055] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0056] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0057] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. An optical receiving component, characterized in that, include: A circuit board having a first conductive pattern, the first conductive pattern including multiple pairs of differential signal lines and multiple ground lines at the receiving end, the multiple ground lines being arranged in parallel, and a pair of differential signal lines being arranged between two adjacent ground lines; An arrayed waveguide grating is used to receive optical signals and demultiplex the optical signals before outputting them. A photodetector is used to receive the optical signal output by the arrayed waveguide grating and convert it into an electrical signal for output. A transimpedance amplifier is electrically connected to the photodetector and the circuit board respectively. The transimpedance amplifier is used to receive the electrical signal output by the photodetector, process the electrical signal and output it. The signal output terminal of the transimpedance amplifier includes multiple pairs of differential signal terminals and multiple ground terminals. The multiple ground terminals are arranged side by side, and a pair of differential signal terminals is arranged between two adjacent ground terminals. A substrate is provided on the substrate, the second conductive pattern including multiple pairs of fan-out differential traces and multiple fan-out ground lines, the multiple fan-out ground lines are fan-out side by side, and a pair of fan-out differential traces are provided between two adjacent fan-out ground lines, the transimpedance amplifier is electrically connected to the circuit board through the second conductive pattern; The fan-out differential trace is located between the signal output terminal of the transimpedance amplifier and the differential signal line of the first conductive pattern. The fan-out differential trace includes a first end and a second end. The first end faces the transimpedance amplifier and is electrically connected to the corresponding differential signal terminal. The second end faces the differential signal line of the first conductive pattern and is electrically connected to the corresponding differential signal line. The distance between the first ends of any two adjacent pairs of fan-out differential traces is smaller than the distance between the second ends. One end of the fan-out ground wire is electrically connected to the ground terminal of the corresponding transimpedance amplifier, and the other end is electrically connected to the ground wire of the corresponding first conductive pattern.

2. The optical receiving component according to claim 1, characterized in that, The spacing between the first ends of two adjacent pairs of fan-out differential traces is 0.3mm to 0.4mm, and the spacing between the second ends of two adjacent pairs of fan-out differential traces is 0.4mm to 0.6mm.

3. The optical receiving component according to claim 1, characterized in that, The substrate has a ground reference layer on its bottom surface facing away from the second conductive pattern. A ground return via is provided between the fan-out ground line and the ground reference layer. The ground return via is electrically connected to the ground reference layer and the fan-out ground line.

4. The optical receiving component according to claim 1, characterized in that, The optical receiving component further includes bonding wires, which include a first bonding wire, a second bonding wire, and a third bonding wire. The photodetector is electrically connected to the transimpedance amplifier through the first bonding wire, the transimpedance amplifier is electrically connected to the second conductive pattern through the second bonding wire, and the second conductive pattern is electrically connected to the first conductive pattern through the third bonding wire.

5. The optical receiving component according to claim 4, characterized in that, The length of the bonding wire is less than or equal to 0.55 mm.

6. The optical receiving component according to claim 1, characterized in that, The substrate is disposed on the circuit board, and the arrayed waveguide grating, the photodetector and the transimpedance amplifier are all disposed on the substrate.

7. The optical receiving component according to claim 6, characterized in that, The substrate is a single pad, and the arrayed waveguide grating, the photodetector, and the transimpedance amplifier are arranged sequentially on the single pad along the signal transmission direction.

8. The optical receiving component according to claim 6, characterized in that, The substrate includes a first pad and a second pad, the arrayed waveguide grating and the photodetector are disposed on the first pad, and the first pad is a bare block structure; the transimpedance amplifier is disposed on the second pad, and the second conductive pattern is disposed on the surface of the second pad.

9. The optical receiving component according to claim 6, characterized in that, The second conductive pattern also includes device pads, on which the transimpedance amplifier is soldered and connected to the fan-out ground line.

10. The optical receiving component according to claim 6, characterized in that, The second conductive pattern also includes a filter capacitor, which is electrically connected to the circuit board and the transimpedance amplifier, respectively.

11. The optical receiving component according to any one of claims 6-9, characterized in that, The coefficient of thermal expansion of the substrate is less than that of the circuit board. The substrate is any one of a silicon substrate, a ceramic substrate, or a glass substrate.

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