Integrated multi-layer FPC multi-channel light receiving system integrated with digital function

Abstract

The invention relates to the technical field of optical communication, in particular to an integrated multi-layer FPC (Flexible Printed Circuit) multi-channel optical receiving system integrated with a digital function. In the optical communication system architecture, a receiving system is composed of a photoelectric detection chip, a trans-impedance amplifier, a signal processing unit and an optical coupling structure. The photoelectric detection chip, the trans-impedance amplifier and the signal processing unit are integrally arranged in the system, so that the routing length is shortened, miniaturization, high speed and low power consumption of the light receiving unit are realized, and the environmental adaptability and the electromagnetic interference capability are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to an integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions. Background Art

[0002] As the core conversion component of modern information networks, optical communication receiving systems undertake the critical task of efficiently converting optical signals into electrical signals. With the explosive growth of global data traffic, optical communication technology has fully penetrated three core scenarios: gigabit fiber-to-the-home, 5G communication networks, and data center interconnection. Especially in the current wave of large-scale AI model deployment, the demand for high-speed data transmission places unprecedentedly stringent demands on optical communication systems, and their performance is directly related to the transmission quality and reliability of the entire optical communication system. With the rapid development of information technology, the performance requirements for optical communication receiving systems are becoming increasingly stringent, placing stringent demands on miniaturization, high speed, signal integrity, and environmental adaptability.

[0003] Traditional optical communication receivers primarily use photodetector chips such as PDs and APDs as core photosensitive elements. Based on the internal photoelectric effect, photodetector chips generate photocurrent when exposed to light, thereby converting optical signals into electrical signals. However, existing technologies have the following drawbacks: 1. Insufficient sensitivity: Traditional photodiodes have limited ability to detect weak optical signals in low-light environments. After optical signals are transmitted over long optical fibers, the optical power incident on the receiving device is significantly reduced due to factors such as fiber loss. Traditional photodiodes struggle to effectively convert these weak signals, resulting in signal loss or increased bit error rates, limiting the transmission distance and stability of optical communication systems.

[0004] 2. Slow response: In high-speed optical communication systems, at transmission rates of 50 Gbps and above, traditional photodiodes have a slow response speed. This is primarily due to time delays in the generation, transmission, and collection of carriers within them, which cannot keep up with the changing rate of high-speed optical signals. This results in signal distortion and bandwidth limitations, hindering the development of optical communication systems to higher speeds.

[0005] 3. High dark current: Photodiodes generate dark current in the absence of light, which introduces noise, reduces the signal-to-noise ratio, and affects the accuracy of optical signal conversion. The dark current level of existing photodiodes affects the overall performance of optical communication receivers to a certain extent, especially when receiving low-light-intensity signals, where the impact of dark current noise is more significant.

[0006] 4. Low Integration: Currently, many optical communication receiving systems have complex structures and low integration between components, resulting in large size and high cost, which is not conducive to the miniaturization and large-scale deployment of optical communication systems. In practical applications, numerous discrete components such as photodiodes, amplifier circuits, and filter circuits need to be combined and connected. This not only increases the manufacturing process complexity but also easily introduces additional loss and interference during signal transmission.

[0007] 5. Insufficient signal stability: Many optical communication receiving devices require additional decoupling capacitors to adjust the signal output to ensure the stability of communication signal reception, but this method makes it difficult to accurately control signal stability.

[0008] 6. Single-wavelength limitation: Some optical communication receivers can only support single-wavelength optical signals and cannot meet the requirements of multi-wavelength signal reception. Some optical devices that need to receive multiple wavelengths simultaneously must be equipped with multiple receivers, which not only increases device complexity and cost but also reduces coupling yield.

[0009] 7. High-speed transmission challenges: In high-speed optical communication scenarios, existing receiver components face technical bottlenecks in signal integrity, power consumption control, heat dissipation management, and optical packaging accuracy. For example, as transmission rates evolve to 3.2T and above, the technical difficulty of these technologies increases exponentially.

[0010] 8. Limited application scenarios: The application of some optical communication receiving devices is restricted in specific scenarios. For example, in land-based visible light communication, long-distance outdoor communication is susceptible to atmospheric turbulence, precipitation, fog and other weather conditions, which can lead to signal degradation because the signal propagates in free space.

[0011] In summary, the existing optical communication receiving device technology has obvious deficiencies in sensitivity, response speed, dark current control and integration, which makes it difficult to meet the growing demand for high-speed, long-distance and low-cost optical communication networks. A new type of optical communication receiving system is urgently needed to overcome the above defects and improve the performance of the optical communication system. Summary of the Invention

[0012] To address the problem that existing optical communication receivers lack the integration required to meet the needs of optical communication networks, this paper proposes an integrated, multi-layer FPC multi-channel optical receiving system with integrated digital functions. In this optical communication system architecture, the receiving system consists of a photodetection chip, a transimpedance amplifier, a signal processing unit, and an optical coupling structure. The integrated placement of the photodetection chip, transimpedance amplifier, and signal processing unit within the system shortens bonding lengths, enabling miniaturization, high speed, low power consumption, and enhanced environmental adaptability and electromagnetic interference resistance of the optical receiving unit.

[0013] The specific implementation contents of the present invention are as follows: An integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions, comprising a photoelectric detection chip, a transimpedance amplifier and a signal processing unit, a wiring adapter board, and an FPC wiring PIN pin integrated into the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions; A photoelectric detection chip is disposed adjacent to one side of the transimpedance amplifier and the signal processing unit, and an FPC bonding PIN pin is disposed adjacent to the other side of the transimpedance amplifier and the signal processing unit; a bonding adapter board is disposed adjacent to both ends of the transimpedance amplifier and the signal processing unit; The transimpedance amplifier and signal processing unit, wire bonding adapter board, and FPC wire bonding PIN pins are arranged on a multi-layer FPC board; The transimpedance amplifier and the signal processing unit are connected to the wire bonding adapter board, the FPC wire bonding PIN pin, and the photoelectric detection chip through gold wires; The FPC bonding PIN pin is connected to the bonding adapter board via a gold wire; The gold wires connecting the transimpedance amplifier and the signal processing unit with the wire bonding adapter board and the FPC wire bonding PIN pins are routed in staggered layers on the multi-layer FPC board.

[0014] In order to better implement the present invention, further, the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions also includes an SI capacitor; The SI capacitor is arranged on a multi-layer FPC board; In order to better implement the present invention, further, the transimpedance amplifier and the signal processing unit are arranged on the gold layer of the FPC.

[0015] In order to better implement the present invention, further, a through hole is provided below the transimpedance amplifier and the signal processing unit, and the through hole is connected to the ground terminal.

[0016] In order to better implement the present invention, further, the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions also includes an optical coupling structure integrated in the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions; The optical coupling structure includes an integrated part of an SI lens, a wavelength division multiplexer, an SI lens and a glass turning prism arranged in sequence; The signal light passes through the SI lens, wavelength division multiplexer, SI lens and glass turning prism in sequence, and the signal light is turned at an angle of θ and output to the receiving end of the photoelectric detection chip.

[0017] In order to better implement the present invention, further, the transimpedance amplifier and signal processing unit include a signal processing unit, a modulation signal loss detection module, a compensation unit module, and a signal loss detection module integrated in the TIA chip; The input end of the photoelectric detection chip receives signal light through an optical coupling structure, and transmits the output signal light to the signal processing unit, converts the information carried in the optical signal into an electrical signal and outputs it.

[0018] In order to better implement the present invention, further, the signal processing unit is integrated with an I2C digital communication interface and is connected to the register via the I2C digital communication interface.

[0019] In order to better implement the present invention, further, when the FPC is connected by welding, the FPC below the FPC welding position is a hard-flex board with a relatively hard texture.

[0020] In order to better implement the present invention, further, when the FPC is connected by bonding, the FPC below the FPC bonding position is a soft and rigid board.

[0021] The present invention has the following beneficial effects: (1) The present invention integrates the photoelectric detection chip, transimpedance amplifier and signal processing unit into the system, thereby shortening the wire bonding length.

[0022] (2) The optical coupling structure of the present invention adopts a multi-channel wavelength division multiplexing system and SI lens, which shortens the optical path, saves space, and increases the consistency of coupling.

[0023] (3) The transimpedance amplifier and signal processing unit of the present invention are placed on the gold layer of the FPC, which achieves a good heat dissipation effect, realizes the miniaturization, high speed, low power consumption of the light receiving unit, enhances the adaptability to the environment and enhances the electromagnetic interference capability.

[0024] (4) The FPC welding and bonding solutions of the present invention can be reused multiple times, achieving low cost. The transimpedance amplifier and signal processing unit are optimized for signal attenuation, timing jitter, and noise suppression, achieving miniaturization and high-density integration of optical receivers. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of a traditional multi-channel optical receiving device.

[0026] Figure 2 Schematic diagram of the wiring structure of a traditional multi-channel optical receiving device.

[0027] Figure 3 This is a structural schematic diagram of an integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions provided by the present invention.

[0028] Figure 4 This is a schematic diagram of the wiring structure of the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions provided by the present invention.

[0029] Figure 5 This is a schematic diagram of the wiring structure of another integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions provided by the present invention.

[0030] Figure 6 This is a side structural diagram of the FPC bonding solution provided by an embodiment of the present invention.

[0031] Figure 7 A schematic diagram of the internal structure of the FPC bonding solution provided in an embodiment of the present invention.

[0032] Figure 8 A schematic diagram of the side structure of the FPC welding solution provided by an embodiment of the present invention.

[0033] Figure 9 A schematic diagram of the internal structure of the FPC welding solution provided in an embodiment of the present invention.

[0034] Figure 10 This is a simulation diagram of the optical receiving system provided by the present invention.

[0035] Figure 11 This is a schematic diagram of the overall structure of the transimpedance amplifier and signal processing unit provided by the present invention.

[0036] Among them, 1. Wire bonding adapter board, 2. Transimpedance amplifier and signal processing unit, 3. SI capacitor, 4. Photoelectric detection chip, 5. FPC wire bonding PIN pin, 6. SI lens, 7. Wavelength division multiplexer, 8. Integrated part of SI lens and glass turning prism, 9. FPC bonding point, 10. FPC welding point, 11. Through hole, 12. RF trace, 13. RF signal spacing, 14. PD / APD power supply trace, 15. RSSI trace. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] Example 1: This embodiment proposes an integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions, such as Figure 3 As shown, it includes a photoelectric detection chip 4, a transimpedance amplifier and signal processing unit 2, a wire bonding adapter board 1, and an FPC wire bonding PIN foot 5 integrated into the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions; A photodetection chip 4 is provided adjacent to one side of the transimpedance amplifier and signal processing unit 2, and an FPC bonding PIN pin 5 is provided adjacent to the other side of the transimpedance amplifier and signal processing unit 2; a bonding adapter board 1 is provided adjacent to both ends of the transimpedance amplifier and signal processing unit 2; the transimpedance amplifier and signal processing unit 2, the bonding adapter board 1, and the FPC bonding PIN pin 5 are provided on a multilayer FPC board; The transimpedance amplifier and signal processing unit 2 are connected to the wire bonding adapter board 1, the FPC wire bonding PIN pin 5, and the photoelectric detection chip 4 through gold wires; The FPC bonding PIN pin 5 is connected to the bonding adapter board 1 through a gold wire; The gold wires connecting the transimpedance amplifier and the signal processing unit 2 with the wire bonding adapter board 1 and the FPC wire bonding PIN pins 5 are routed in staggered layers on the multi-layer FPC board.

[0040] In order to better implement the present invention, further, the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions further includes an SI capacitor 3; The SI capacitor 3 is arranged on a multi-layer FPC board; The SI capacitor 3 is adjacently arranged between the wire bonding adapter board 1 and the transimpedance amplifier and signal processing unit 2, connected to the wire bonding adapter board 1, the transimpedance amplifier and the signal processing unit 2 through gold wires, and routed in staggered layers inside the multi-layer FPC board.

[0041] Working principle: The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions proposed in this embodiment shortens the wire bonding length by integrating the photodetection chip 4, the transimpedance amplifier and the signal processing unit 2 into the system. Figure 1The traditional multi-channel optical receiver device shown in the figure mainly involves double-layer welded FPCs, which have poor impedance matching and poor production repeatability. Most of them cannot meet the requirements of high-speed applications above 100G and are only suitable for medium and low-speed applications. The integration is not high, and due to the welding of the upper and lower FPCs, repeated welding can easily damage the ceramic parts. Figure 2 Traditional multi-channel optical receiver devices involve traditional TIA wire bonding, which has large step height, long wire bonding length, high wire bonding difficulty, poor RF performance and high production cost.

[0042] like Figure 2 The figure shows a schematic diagram of the wiring structure of a traditional multi-channel optical receiving device, and the right side is an enlarged view of the left part from a top view.

[0043] like Figure 3 As shown, the components involved in this embodiment mainly include FPC bonding PIN pin 5, bonding adapter board 1, special SI capacitor 3, transimpedance amplifier and signal processing unit 2 and APD (PD) part, namely photodetection chip 4. The bonding difficulty is greatly reduced. The bonding adapter board 1, transimpedance amplifier and signal processing unit 2, SI capacitor 3, photodetection chip 4 and FPC bonding PIN pin 5 are directly connected by gold wire. SI capacitor 3 is conducive to eliminating signal noise generated by high frequency. The bonding length is greatly reduced, and the bonding difficulty is reduced. It is suitable for large-scale production. FPC does not need to be welded multiple times, and FPC can be directly bonded or directly welded, which greatly saves costs and improves integration. It is suitable for applications with speeds above 50G. The bonding step height is also greatly reduced, and the high-frequency performance is greatly improved.

[0044] In this embodiment, the transimpedance amplifier and signal processing unit 2 is placed adjacent to the FPC bonding pins 5 on the bonding adapter board 1, significantly reducing bonding difficulty and requiring lower bonding precision. The transimpedance amplifier and signal processing unit 2 is placed adjacent to the photodetector chip 4, i.e., the PD or APD, allowing for extremely short gold wire bonding lengths. This short wire length provides excellent impedance matching, enhancing product performance.

[0045] This embodiment provides an integrated multi-layer FPC multi-channel optical receiving system with multi-layer bonding or welding FPC and integrated digital functions. Compared with similar optical devices, this optical device does not have the welding of FPC and ceramic parts, and will not produce impedance discontinuity at the welding point. It can provide higher operating bandwidth and higher product performance. FPC is directly welded or bonded to FPC, which greatly reduces the possibility of impedance discontinuity and saves the cost of ceramic parts.

[0046] Impedance matching of optical receivers in optical communications applications with speeds above 50G is extremely difficult. However, this embodiment achieves excellent impedance matching for the optical receiver, including the photodetector chip 4 (i.e., PD or APD), the transimpedance amplifier, and the signal processing unit 2. A very short gold wire connects the transimpedance amplifier and the photodetector chip 4 (i.e., PD or APD), improving the integration of the optical receiver, effectively utilizing space, and simplifying the manufacturing process.

[0047] This embodiment is different from the traditional solution. The built-in transimpedance amplifier and photodetection chip 4, namely PD or APD, of this design realize multi-channel and high-density fit. Since the optical device FPC only needs to be soldered once, most of the remaining parts can be completed by bonding. When the internal transimpedance amplifier and photodetection chip 4, namely PD or APD are damaged, it is also relatively convenient to replace them, which solves the problem of troublesome replacement. The built-in transimpedance amplifier and photodetection chip 4, namely PD or APD of this embodiment can also be replaced according to different product solutions. Unlike other original solutions, the other novelty of this embodiment is that it is compatible with various forms of amplitude modulation signals, such as PAM4 and NRZ input signals, and is suitable for high-speed optical devices with a rate greater than 50G, which greatly reduces the cost problem of the original solution.

[0048] like Figure 3 As shown, the bonding capacitor in this embodiment can be either an SI capacitor 3 or a ceramic capacitor. This receiving system has wide applicability. The bonding capacitor serves to stabilize the DC voltage and filter noise when receiving high-frequency signals. The SI capacitor 3 has better pressure resistance and mechanical properties and is suitable for more complex environments. Ceramic capacitors are suitable for general environments. The choice of capacitor can be based on cost and environment.

[0049] Example 2: This embodiment is based on the above embodiment 1. Figure 3 、 Figure 4 、 Figure 5As shown, this embodiment implements an anti-interference design for the routing in the designed FPC, namely, through a staggered design; the RF signal lines are staggered up and down, and this is achieved by balancing and optimizing the length of the RF trace 12, the spacing 13 of the RF signal, and the thickness. A common ground setting is added between each channel RF. By increasing the number of through holes 11 below the transimpedance amplifier TIA, all through holes 11 are grounded, increasing the common ground space, and also facilitating heat conduction of the transimpedance amplifier TIA. This type of FPC can be directly welded or bonded together, broadening the application field and being suitable for multi-channel, high-speed optical receiving system applications with a rate of 50G or above for each channel. In addition, the individual RF wire PIN pins on the FPC have a special impedance design to perform impedance adaptation for the transimpedance amplifier and signal processing unit 2, and can also be applied to optical receiving systems with a single channel rate of 100G or above. The special impedance design in this embodiment is mainly impedance matching. For example, the output impedance of the transimpedance amplifier (TIA) is 90 ohms. The FPC design must be compensated according to the output to be close to the output resistance of the TIA. Because there are welding points and gold wire connection points in the output process, which have an impact on the output impedance, the FPC design is to match and compensate with the transimpedance amplifier (TIA).

[0050] This embodiment Figure 4 The dark blue frame is the transimpedance amplifier and signal processing unit 2, the blue line is the FPC bonding PIN 5, and the red circle below the dark blue frame is the through hole 11.

[0051] This embodiment Figure 5 The dark blue frame is the transimpedance amplifier and signal processing unit 2, the gray line is the RF high-frequency signal line, namely the RF trace 12, the blue line is the remaining FPC traces, the red circle below the dark blue frame is the through hole 11, and the distance between the two FPC bonding PIN pins 5 is the RF signal spacing 13.

[0052] The interference in this embodiment is the interference between one channel and another channel. Since one channel consists of two RF traces 12 and the RF traces 12 are differential outputs, the two RF traces 12 of one channel are on the same layer. The RF traces 12 of different channels are not on the same layer, and the remaining traces can be distributed randomly.

[0053] like Figure 3 As shown, the power supply trace 14 connecting the transimpedance amplifier and signal processing unit 2 and the photodetection chip 4, the RF trace 12 connecting the transimpedance amplifier and signal processing unit 2 and the FPC bonding PIN pin 5, and the RSSI trace 15 connecting the transimpedance amplifier and signal processing unit 2 and the FPC bonding PIN pin 5 are staggered. In this embodiment, a staggered design is adopted. If the multi-layer FPC board has a total of 4 layers, the power supply trace 14 of the photoelectric detection chip 4 corresponding to the transimpedance amplifier and the signal processing unit 2 can be set on the first layer of the multi-layer FPC board, and the photocurrent detection trace of the transimpedance amplifier and the signal processing unit 2, that is, the RSSI trace 15 of the RSSI photocurrent below, is set on the second layer of the multi-layer FPC board. The RF traces 12 are randomly set on different layers of the multi-layer FPC board; the two RF traces 12 in the same channel are on the same layer, and the RF traces 12 of different channels are not on the same layer, and their RF traces 12 can be randomly distributed; that is, the two RF traces 12 in the same channel are on the same layer; If the multi-layer FPC board has a total of 6 layers, the power supply line 14 of the photodetection chip 4 is connected to the transimpedance amplifier and signal processing unit 2 and the FPC bonding PIN pin 5 to achieve random staggered routing on the multi-layer FPC board; for example, the power supply line 14 of the photodetection chip 4 can be routed on the first and third layers respectively through the FPC bonding PIN pin 5 of the transimpedance amplifier and signal processing unit 2 and the RF line 12 of the transimpedance amplifier and signal processing unit 2, staggering the RF line 12, and a ground line can be routed between layers to resist interference, that is, the effect of separating the layers with a ground line will be better, so that the two RF lines 12 in one channel are isolated from the two RF lines 12 in another channel.

[0054] The FPC in this embodiment uses a flexible and rigid board with a multi-layer wiring arrangement. It is bonded to the tube shell through a rigid board and connected to the internal chip through wiring. The FPC has good mechanical stability and good heat dissipation. Metallized wiring and metallized patterns can be made on the FPC. The transimpedance amplifier TIA is directly attached to the metallized pattern of the FPC rigid board through conductive glue, so that the gnd at the bottom of the transimpedance amplifier TIA can be directly connected to the gnd of the metallized pattern of the FPC rigid board. This design method increases the grounding effect of the transimpedance amplifier TIA, improves the performance of the optical receiving device, and can better realize flexible assembly and interconnection with subsequent optical modules.

[0055] In this embodiment, each channel of the multi-layer FPC is equipped with an anti-interference design, an impedance matching design, and a shortened RF trace 12, so that the invention can be adapted to a single-channel 100G optical receiving system.

[0056] The rest of this embodiment is the same as that of the above-mentioned embodiment 1, and therefore will not be described in detail.

[0057] Example 3: This embodiment is based on any one of the above embodiments 1 to 2. Figure 6 、 Figure 7 、 Figure 8 、 Figure 9As shown, the high integration of the present invention is demonstrated again, and two assembly methods of FPC, namely welding and bonding, are demonstrated. The two schemes of FPC welding and bonding can be used in two different schemes: in the FPC welding scheme, the FPC under the welding point is a hard-soft board; and in the FPC bonding scheme, the FPC under the FPC bonding point is also a hard-soft board, but it is softer than the former, suitable for different needs and different working environments. After the FPC on the welding point or bonding point is damaged, it is convenient to replace. This embodiment not only takes into account the practicality of the FPC, but also the integration of the optical path. In this embodiment, the signal light passes through the SI lens 6, the wavelength division multiplexer 7, the integrated part 8 of the SI lens and the glass turning prism and the receiving photodetection chip 4, namely the PD or APD, to form a basic optical path. Then the receiving photodetection chip 4, namely the PD or APD, is directly connected to the transimpedance amplifier and the signal processing unit 2 through the gold wire to convert the information carried in the optical signal into an electrical signal output.

[0058] The rest of this embodiment is the same as any of the above-mentioned embodiments 1 and 2, and thus will not be described in detail.

[0059] Example 4: This embodiment is based on any one of the above embodiments 1 to 3. Figure 10 As shown, the internal structure of the optical receiving system is described using a specific embodiment.

[0060] From the side view of the optical receiving system, the signal light passes through the SI lens 6, the wavelength division multiplexer 7, and then passes through an integrated component 8 of an SI lens and a glass turning prism. The light is turned at an angle of θ (about 43° or 47°, depending on the needs. These two angles are selected to prevent light reflection) and then hits the receiving end of the photodetector chip 4, i.e., the PD or APD, to achieve lossless reception of the optical signal. Figure 10The X-axis of the simulation result graph on the right side of the center represents the length of the cross-section of the signal light spot on the photodetector chip 4, i.e., the PD or APD, and the Y-axis represents the width of the cross-section of the signal light spot on the photodetector chip 4, i.e., the PD or APD. Because the refractive index of the SI material near a wavelength of 1310 nm is approximately 3.5, which is higher than that of a typical glass lens, the front and rear SI lenses are combined, namely, the SI lens 6 and a portion of the integrated SI lens and glass turning prism 8, respectively. The integrated SI lens and glass turning prism 8 can be disassembled or bonded for use. Based on the current SI material cost and mature domestic manufacturing process, it can even be made into an integrated SI turning focusing prism, increasing the adaptability and substitutability of the system. The integrated SI lens and glass turning prism 8 can compress the light spot very small, with a very short focal length and minimal light spot distortion. The simulation results show that the system wavelength is 1310 nm (1.31 microns) and the coupling efficiency is 0.964 (96.4%). During the coupling process, the SI lens can be defocused (that is, after the SI lens is moved to the position of maximum system receiving efficiency, the SI lens position is moved again to reduce the receiving efficiency a little. When the system works at high temperature, the thermal lens effect of the SI lens and the mutual compensation between the two SI material lenses are utilized: the compensation between parameters such as the curvature and cone coefficient of the two SI lenses is utilized). After the defocusing process, the system receives very little attenuation of the signal light at high temperature, thereby increasing the stability of the receiving system. In recent years, due to the development of the communications field, SI materials have been used more and more, becoming cheaper and cheaper, and the manufacturing process has become more mature. The SI lens of this embodiment can also use aspheric lenses, which greatly reduces the process requirements for lens manufacturing, greatly reduces the cost, and significantly shortens the manufacturing time. In addition, the SI material lens will have a significantly shorter focal length than the glass lens, thereby increasing the system concentration. This embodiment is different from the conventional 850nm wavelength receiving solution on the market because the SI material has very poor transmittance to 850nm signal light.

[0061] The rest of this embodiment is the same as any one of the above-mentioned embodiments 1 to 3, and thus will not be described in detail.

[0062] Example 5: This embodiment is based on any one of the above embodiments 1 to 4. Figure 11 As shown, the internal structure of the TIA chip is described using a specific embodiment.

[0063] To address the issue that most traditional TIAs lack signal loss detection (LOSD) and modulation signal loss detection (LMD) functions, the transimpedance amplifier (TIA) in this embodiment is a multi-channel linear TIA that supports single-channel rates of 100G and above. The integrated signal processing unit integrates the signal loss detection, modulation signal loss detection, and compensation unit functions into the TIA chip, enabling rapid determination of whether the problem lies with the received signal light or the TIA itself. The transimpedance amplifier and signal processing unit 2 in this embodiment also integrate an I2C digital communication interface, directly connecting the bonding adapter board 1, the transimpedance amplifier and signal processing unit 2, and the bonding PIN pins on the FPC via gold wires. The photodetector chip 4, or PD (APD), is also directly connected to the transimpedance amplifier and signal processing unit 2 via gold wires. Each TIA function can be written to a register via the I2C digital communication interface, with data transmission achieved via the SDA and SCL data lines, enabling register control of each TIA function. A polarity inversion function is also provided: This function inverts the output differential signal, increasing system compatibility. Since the differential output has two output terminals and two RF outputs, for example, outputs of 0 and 1 are inverted to 1 and 0. The transimpedance amplifier and signal processing unit 2 detects the RSSI photocurrent value through the I2C digital interface, determines the input signal light intensity, and appropriately compensates the signal light, improving the output electrical signal linearity, output performance, and electrical signal integrity. It also provides gain modulation in two modes: AGC (automatic gain mode) and MGC (manual gain mode), facilitating different needs and expanding the application scenarios of the entire optical receiving system.

[0064] Working principle: The transimpedance amplifier and signal processing unit 2 of this embodiment can provide an automatic gain control function, which can maintain a constant output under different input currents, ensuring that the device works stably under different light intensity environments. At the same time, the transimpedance amplifier and signal processing unit 2 also have a compensation function, which can compensate for the electrical signal converted from the modulated optical signal according to different low-frequency and high-frequency signals; the transimpedance amplifier and signal processing unit 2 have a signal loss detection function, and when the RSSI photocurrent signal is detected to be lost, feedback will be provided through the digital module; the built-in transimpedance amplifier and signal processing unit 2 also has a detection function for the loss of the modulation signal, and determines the modulation loss situation by comparing the threshold setting with the peak detector.

[0065] This embodiment enables multi-channel 200G, 400G, and even 800G data transmission. It uses an I2C communication interface to control TIA performance. I2C communication uses the host to send start and stop conditions. When SCL is high, SDA transitions from high to low, indicating a start signal; SDA transitions from low to high, indicating a stop signal. Repeated start conditions are similar to start conditions and are only used during read cycles. Registers are used to write various transimpedance amplifier (TIA) performance parameters. Through the I2C communication interface, the output amplitude, output bandwidth, output current, RSSI dark current, and other parameters can be adjusted to improve and optimize device sensitivity and bandwidth.

[0066] The rest of this embodiment is the same as any one of the above-mentioned embodiments 1 to 4, and thus will not be described in detail.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. An integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions, characterized in that: It comprises a photoelectric detection chip (4), a transimpedance amplifier and a signal processing unit (2), a wire bonding adapter board (1), and an FPC wire bonding PIN pin (5) which are integrated into the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions; The transimpedance amplifier and signal processing unit (2), the wire bonding adapter board (1), and the FPC wire bonding PIN pins (5) are arranged on a multi-layer FPC board; A photoelectric detection chip (4) is disposed adjacent to one side of the transimpedance amplifier and signal processing unit (2), and an FPC bonding PIN pin (5) is disposed adjacent to the other side of the transimpedance amplifier and signal processing unit (2); bonding adapter boards (1) are disposed adjacent to both ends of the transimpedance amplifier and signal processing unit (2); The transimpedance amplifier and signal processing unit (2) are connected to the wire bonding adapter board (1), the FPC wire bonding PIN pin (5), and the photoelectric detection chip (4) via gold wires; The FPC bonding PIN pin (5) is connected to the bonding adapter plate (1) via a gold wire; The gold wires connecting the transimpedance amplifier and signal processing unit (2) to the wire bonding adapter board (1) and the FPC wire bonding PIN pins (5) are arranged in staggered layers on the multi-layer FPC board.

2. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to claim 1, characterized in that: A through hole (11) is provided below the transimpedance amplifier and signal processing unit (2), and the through hole (11) is connected to the ground.

3. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to claim 1, characterized in that: The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions further includes an SI capacitor (3); The SI capacitor (3) is arranged on a multi-layer FPC board and is connected to the wire bonding adapter board (1), the transimpedance amplifier and the signal processing unit (2) via gold wires.

4. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to claim 1, characterized in that: The transimpedance amplifier and signal processing unit (2) are arranged on the gold layer of the FPC.

5. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to claim 1, characterized in that: The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions further includes an optical coupling structure integrated in the integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions; The optical coupling structure includes an SI lens (6), a wavelength division multiplexer (7), and an integrated component (8) of an SI lens and a glass turning prism, which are arranged in sequence; The signal light passes through the SI lens (6), the wavelength division multiplexer (7), and the integrated component (8) of the SI lens and the glass turning prism in sequence, and the signal light is turned at an angle θ and then output to the receiving end of the photoelectric detection chip (4).

6. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to claim 1, characterized in that: The transimpedance amplifier and signal processing unit (2) includes a signal processing unit, a modulation signal loss detection module, a compensation unit module, and a signal loss detection module integrated in a TIA chip; The input end of the photoelectric detection chip (4) receives signal light through an optical coupling structure, and transmits the output signal light to the transimpedance amplifier and the signal processing unit (2), converting the information carried in the optical signal into an electrical signal and outputting the electrical signal.

7. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to claim 6, characterized in that: The transimpedance amplifier and signal processing unit (2) is integrated with an I2C digital communication interface and is connected to the register via the I2C digital communication interface.

8. The integrated multi-layer FPC multi-channel optical receiving system with integrated digital functions according to any one of claims 1 to 7, characterized in that: When the FPC is connected by welding or bonding, the FPC at the welding point and the FPC below the bonding point are soft-rigid boards.

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