Design method of high-speed optical fiber image data transmission

Abstract

The present invention relates to the field of aerospace application imaging technology, and in particular to a high-speed optical fiber image data transmission design method, including: A1. Calculating the maximum amplitude value of a high-speed differential GTX signal stably sent by a data transmitter within a full temperature range, the minimum amplitude value of a high-speed differential GTX signal stably received by a data receiver within a full temperature range, and the insertion loss of a ceramic capacitor within a full temperature range; A2. Determining the insertion loss range of a circuit board according to the maximum amplitude value of the high-speed differential GTX signal, the minimum amplitude value of the high-speed differential GTX signal, and the insertion loss; A3. Constraining the transmission distance of the high-speed differential GTX signal on the circuit board according to the insertion loss range. The present invention reduces the insertion loss of a transmission link by shortening the wiring between an imaging controller and an optical fiber module, thereby improving the reliability of data transmission.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace application imaging, and in particular relates to a design method for high-speed optical fiber image data transmission. Background Art

[0002] High-speed fiber-optic image data transmission based on aerospace applications is mainly based on high-speed differential GTX (Gigabit Transceiver) signal transmission between the imaging controller and the fiber module. In order to avoid mutual interference of DC levels and the influence of DC level mismatch, AC coupling is used between the imaging controller and the fiber module for high-speed differential GTX signal transmission. Since ceramic capacitors are easily affected by space radiation, small package capacitors based on materials such as nickel electrodes cannot be selected. Only large package ceramic capacitors can be selected. In the process of high-speed differential GTX signal transmission, two challenges are encountered: (1) large package ceramic capacitors and long routing lead to excessive insertion loss; (2) impedance mismatch caused by high-speed differential GTX signals passing through large-size pads and using vias to change layers will lead to excessive return loss. Summary of the invention

[0003] In view of this, the present invention aims to provide a high-speed optical fiber image data transmission design method to solve the technical problem of excessive insertion loss caused by large package ceramic chip capacitors and too long wiring.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A high-speed optical fiber image data transmission design method, the transmission link of the high-speed optical fiber image data is: the high-speed differential GTX signal emitted from the imaging controller is connected to the differential via via a microstrip line and a stripline, then connected to the capacitor via the microstrip line, and finally connected to the optical fiber module via the microstrip line; the high-speed differential GTX signal emitted from the optical fiber module is connected to the ceramic capacitor via a microstrip line, then connected to the differential via via a microstrip line and a stripline, and finally connected to the imaging controller via the microstrip line. The design method includes reducing the insertion loss of the transmission link by shortening the routing between the imaging controller and the optical fiber module, and specifically includes the following steps:

[0006] A1: The maximum amplitude value V of the high-speed differential GTX signal stably sent by the transmitter over the full temperature range is calculated by statistical data send_max 、The minimum amplitude value V that the data receiving end needs to stably receive high-speed differential GTX signals within the full temperature range receive_min , Insertion loss of ceramic capacitors over the full temperature range cap ; Wherein, the imaging controller serves as a data transmitting end and the optical fiber module serves as a data receiving end, or the imaging controller serves as a data receiving end and the optical fiber module serves as a data transmitting end;

[0007] A2: According to the maximum amplitude value V send_max , minimum amplitude value V receive_min and insertion loss cap , determine the insertion loss range of the circuit board board :

[0008]

[0009] A3: According to the insertion loss range board , constraining the transmission distance of high-speed differential GTX signals on the circuit board board ; Among them, the transmission distance lenth board The constraints are as follows:

[0010]

[0011] Where, f represents the fundamental frequency of the high-speed differential GTX signal, w1 represents the width of the microstrip line, T represents the thickness of the microstrip line, and Z0 represents the transmission impedance; Indicates the dielectric constant of the circuit board material. It represents the loss factor of the circuit board material, and k represents the proportional coefficient of the circuit board loss material.

[0012] Furthermore, the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller is compared with the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module. If the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller is smaller than the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module, the imaging controller is used as the data sending end; if the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module is smaller than the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller, the optical fiber module is used as the data sending end.

[0013] Furthermore, the design method further includes reducing the return loss of the transmission link by adjusting the impedance of the ceramic capacitor pad, which specifically includes the following steps:

[0014] B1: Determine the number of pad reference layers to be removed based on the width w1 of the microstrip line and the width w2 of the ceramic capacitor pad; the number of pad reference layers to be removed must meet the following constraints:

[0015]

[0016] in, It represents the distance between the pad reference layer and the nearest reference layer after the i-1 layer is removed, h1 represents the distance between the surface layer of the ceramic capacitor and the first pad reference layer, hi represents the distance between the i-1th pad reference layer and the i-th pad reference layer, h(i+1) represents the distance between the i-th pad reference layer and the i+1th pad reference layer, Δhi represents the thickness of the i-th pad reference layer itself; Δh(i-1) represents the thickness of the i-1th pad reference layer itself;

[0017] B2: Calculate the impedance value Z of the ceramic capacitor pad based on the number of removed layers of the pad reference layer pad ; Among them, the impedance value Z pad The calculation formula is as follows:

[0018]

[0019] Among them, E r represents the dielectric constant of the medium, and D represents the spacing of the transmission lines;

[0020] B3: Compare the impedance value Z of the ceramic capacitor pad pad The impedance value Z in the optical fiber module diff_gx , if the impedance value Z pad Equal to the impedance value Z diff_gx , the width of each removed layer is the same as the width w2 of the ceramic capacitor pad; if the impedance value Z pad Less than the impedance value Z diff_gx , increase the width of each removal layer; if the impedance value Z pad Greater than the impedance value Z diff_gx , reduce the number of removed layers of the pad reference layer.

[0021] Furthermore, the design method also includes reducing the return loss of the transmission link by adjusting the impedance of the differential via, specifically including:

[0022] By adjusting the center distance s of the two differential vias, the via radius r, and the diameter d of the anti-pad, the impedance value Z of the two differential vias is via The impedance value is the same as that in the optical fiber module; the impedance value of the differential via is Z via The calculation formula is as follows:

[0023]

[0024] Among them, E r It represents the dielectric constant of the medium;

[0025] At the same time, the center distance between the companion ground via and its adjacent differential via is set to the diameter d of the anti-pad.

[0026] Compared with the prior art, the invention can achieve the following beneficial effects:

[0027] 1. Control the impedance values ​​of single-ended signals and differential signals on the transmission link to make them the same as the impedance values ​​in the optical fiber module, ensure that there is no impedance change on the transmission link, and reduce the impact of link reflection;

[0028] 2. By shortening the wiring between the imaging controller and the optical fiber module, the insertion loss of the transmission link is reduced, thereby improving the reliability of data transmission;

[0029] 3. By adjusting the impedance of the ceramic capacitor and the impedance of the differential via, the return loss of the transmission link is limited to an allowable range, thereby improving the reliability of data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0031] Figure 1 Schematic diagram of a transmission link of high-speed optical fiber image data according to an embodiment of the present invention;

[0032] Figure 2 It is a flowchart of a method for designing high-speed optical fiber image data transmission according to an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of the stacking corresponding to the large package ceramic chip capacitor described in the embodiment of the invention;

[0034] Figure 4 It is a schematic diagram of the placement of differential vias described in an embodiment of the invention.

[0035] Explanation of the reference numerals: imaging controller 1, optical fiber module 2, microstrip line 3, strip line 4, first differential via 5, second differential via 6, ceramic capacitor 7, first ground via 8, second ground via 9, ceramic capacitor pad 10. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0039] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0040] The following will refer to Figure 1-Figure 4 The invention is described in detail with reference to the embodiments.

[0041] The present invention provides a high-speed optical fiber image data transmission design method, wherein the high-speed optical fiber image data is transmitted between an imaging controller and an optical fiber module through a circuit board, the imaging controller adopts but is not limited to the FPGA and refresh chip of Shanghai Fudan Microelectronics Co., Ltd., and the optical fiber module adopts but is not limited to the HTM8501-MH-Q002LZ-Y of AVIC Optoelectronics Technology Co., Ltd.

[0042] High-speed fiber-optic image data transmission link such as Figure 1 As shown, the high-speed differential GTX signal emitted from the imaging controller 1 is connected to the first differential via 5 via the microstrip line 3, then connected to the second differential via 6 via the stripline 4, then connected to the ceramic capacitor 7 via the microstrip line 3, and finally connected to the optical fiber module 2 via the microstrip line 3; the high-speed differential GTX signal emitted from the optical fiber module 2 is connected to the ceramic capacitor 7 via the microstrip line 3, then connected to the second differential via 6 via the microstrip line 3, then connected to the first differential via 5 via the stripline 4, and finally connected to the imaging controller 1 via the microstrip line 3.

[0043] The imaging controller 1 and the optical fiber module 2 can both serve as a data transmitter and a data receiver. When the imaging controller 1 serves as a data transmitter, the optical fiber module 2 serves as a data receiver; when the optical fiber module 2 serves as a data transmitter, the imaging controller 1 serves as a data receiver.

[0044] In order to solve the problem of excessive insertion loss caused by large package ceramic capacitors and too long wiring, the invention first selects the material of the circuit board and adopts a board with low dielectric constant and loss factor to initially reduce the insertion loss of the transmission link (i.e., the insertion loss of high-speed optical fiber image data during the transmission process). Secondly, the insertion loss of the transmission link is reduced by shortening the wiring between the imaging controller and the optical fiber module. The specific process is as follows: Figure 2 As shown, the following steps are included:

[0045] A1: The maximum amplitude value V of the high-speed differential GTX signal stably sent by the transmitter over the full temperature range is calculated by statistical data send_max 、The minimum amplitude value V that the data receiving end needs to stably receive high-speed differential GTX signals within the full temperature range receive_min , Ceramic capacitor 7 insertion loss loss over the full temperature range cap .

[0046] Compare the maximum amplitude value of the high-speed differential GTX signal sent by the imaging controller 1 with the maximum amplitude value of the high-speed differential GTX signal sent by the optical fiber module 2. If the maximum amplitude value of the high-speed differential GTX signal sent by the imaging controller 1 is smaller than the maximum amplitude value of the high-speed differential GTX signal sent by the optical fiber module 2, the imaging controller 1 is used as the data sending end, and it is determined that the imaging controller 1 can stably send the maximum amplitude value V of the high-speed differential GTX signal. send_max If the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module 2 is less than the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller 1, the optical fiber module 2 is used as the data transmitting end, and it is determined that the optical fiber module 2 can stably emit the maximum amplitude value V of the high-speed differential GTX signal. send_max .

[0047] Similarly, confirm that the data receiving end can stably receive the minimum amplitude value V of the high-speed differential GTX signal within the full temperature range. receive_min .

[0048] A2: According to the maximum amplitude value V send_max , minimum amplitude value V receive_min and insertion loss cap Determine the insertion loss range of the circuit board board :

[0049] .

[0050] A3: According to the insertion loss range of the circuit board board , constraining the transmission distance of high-speed differential GTX signals on the circuit board.

[0051] The transmission distance allowed by high-speed differential GTX signals on the circuit board is lenth board The constraints are:

[0052]

[0053] Where, f represents the fundamental frequency of the high-speed differential GTX signal, w1 represents the width of the microstrip line, T represents the thickness of the microstrip line, and Z0 represents the transmission impedance; Indicates the dielectric constant of the circuit board material. It represents the loss factor of the circuit board material, and k represents the proportional coefficient of the circuit board loss material.

[0054] The transmission distance allowed is board It can reduce the insertion loss of high-speed optical fiber image data during transmission, thereby improving the reliability of data transmission.

[0055] There are two links where impedance changes occur in the transmission link of high-speed differential GTX signals. One link is the large-size coupling capacitor, and the other link is the differential via for signal layer switching.

[0056] To address the problem of excessive return loss caused by impedance mismatch when high-speed differential GTX signals pass through large-sized coupling capacitor pads and use via layer switching, the present invention regulates the impedance of the ceramic capacitor and the impedance of the differential via, thereby limiting the return loss of the transmission link to an allowable range and improving the reliability of data transmission.

[0057] For large-sized coupling capacitors, the present invention reduces the return loss of the transmission link by adjusting the impedance of the ceramic capacitor, which specifically includes the following steps:

[0058] B1: Determine the number of layers to be removed from the pad reference layer based on the width w1 of the microstrip line and the width w2 of the ceramic capacitor pad.

[0059] like Figure 3 As shown, the number of removed layers of the pad reference layer meets the following constraints:

[0060]

[0061] in, It represents the distance between the pad reference layer and the nearest reference layer after the i-1 layer is removed, h1 represents the distance between the surface layer of the ceramic capacitor and the first pad reference layer, hi represents the distance between the i-1th pad reference layer and the i-th pad reference layer, h(i+1) represents the distance between the i-th pad reference layer and the i+1th pad reference layer, Δhi represents the thickness of the i-th pad reference layer itself; Δh(i-1) represents the thickness of the i-1th pad reference layer itself, and T represents the routing thickness of the microstrip line.

[0062] B2: Calculate the impedance value of the ceramic capacitor pad based on the number of layers removed from the pad reference layer .

[0063] Impedance value of ceramic capacitor pad The calculation formula is as follows:

[0064]

[0065] Among them, E r represents the dielectric constant of the medium, and D represents the spacing of the transmission lines;

[0066] B3: Compare the impedance value Z of the ceramic capacitor pad pad The impedance value Z in the optical fiber module diff_gx , if the impedance value Z pad Equal to the impedance value Z diff_gx , the width of each removed layer is the same as the width w2 of the ceramic capacitor pad; if the impedance value Z pad Less than the impedance value Z diff_gx , increase the width of each removed layer, so that the width of each removed layer is greater than the width w2 of the ceramic capacitor pad, and adjust the impedance of the ceramic capacitor pad by increasing the width of each removed layer. The specific width is implemented by simulation software such as HFSS; if the impedance value Z pad Greater than the impedance value Z diff_gx , reduce the number of removed layers of the pad reference layer by 1.

[0067] For differential vias, the invention reduces the return loss of the transmission link by adjusting the impedance of the differential vias, specifically including:

[0068] By adjusting the center distance s of the two differential vias, the via radius r, and the diameter d of the anti-pad, the impedance value Z of the two differential vias is via The same impedance value as inside the fiber optic module.

[0069] like Figure 4 As shown, the impedance value Z of the first differential via 5 and the second differential via 6 is via The calculation formula is as follows:

[0070]

[0071] Among them, E r Represents the dielectric constant of the medium.

[0072] At the same time, the center distance between the first companion ground via 8 and its adjacent first differential via 5 and the center distance between the second companion ground via 9 and its adjacent second differential via 6 are both set to the diameter d of the anti-pad.

[0073] Through the above settings, the return loss of the transmission link is limited to an allowable range, thereby ensuring the reliability of data transmission.

[0074] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0075] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for high-speed optical fiber image data transmission, wherein the transmission link of high-speed optical fiber image data is: a high-speed differential GTX signal emitted from an imaging controller is connected to a differential via via a microstrip line and a stripline, then connected to a capacitor via a microstrip line, and finally connected to an optical fiber module via a microstrip line; a high-speed differential GTX signal emitted from an optical fiber module is connected to a ceramic capacitor via a microstrip line, then connected to a differential via via a microstrip line and a stripline, and finally connected to an imaging controller via a microstrip line, wherein: The design method includes reducing the insertion loss of the transmission link by shortening the wiring between the imaging controller and the optical fiber module, and specifically includes the following steps: A1: The maximum amplitude value V of the high-speed differential GTX signal stably sent by the statistical data transmitter over the full temperature range send_max 、The minimum amplitude value V that the data receiving end needs to stably receive high-speed differential GTX signals within the full temperature range receive_min , Insertion loss of ceramic capacitors over the full temperature range cap ; Wherein, the imaging controller serves as the data transmitting end and the optical fiber module serves as the data receiving end, or the imaging controller serves as the data receiving end and the optical fiber module serves as the data transmitting end; A2: According to the maximum amplitude value V send_max , minimum amplitude value V receive_min and insertion loss cap , determine the insertion loss range of the circuit board board : A3: According to the insertion loss range board , constraining the transmission distance of high-speed differential GTX signals on the circuit board board ; Among them, the transmission distance lenth board The constraints are as follows: Where, f represents the fundamental frequency of the high-speed differential GTX signal, w1 represents the width of the microstrip line, T represents the thickness of the microstrip line, and Z0 represents the transmission impedance; Indicates the dielectric constant of the circuit board material. It represents the loss factor of the circuit board material, and k represents the proportional coefficient of the circuit board loss material.

2. The high-speed optical fiber image data transmission design method according to claim 1, characterized in that: Compare the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller with the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module. If the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller is smaller than the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module, the imaging controller is used as the data sending end; if the maximum amplitude value of the high-speed differential GTX signal emitted by the optical fiber module is smaller than the maximum amplitude value of the high-speed differential GTX signal emitted by the imaging controller, the optical fiber module is used as the data sending end.

3. The high-speed optical fiber image data transmission design method according to claim 1, characterized in that: The design method also includes reducing the return loss of the transmission link by adjusting the impedance of the differential via, specifically including: By adjusting the center distance s of the two differential vias, the via radius r, and the diameter d of the anti-pad, the impedance value Z of the two differential vias is via The impedance value is the same as that in the optical fiber module; the impedance value of the differential via is Z via The calculation formula is as follows: Among them, E r It represents the dielectric constant of the medium; At the same time, the center distance between the companion ground via and its adjacent differential via is set to the diameter d of the anti-pad.

Images