Patent Application
20110320183
1. Technical Field
Embodiments of the present disclosure relates to circuit simulating methods, and more particularly, to a computing device and a method for analyzing differential transmission lines port relationships of a circuit board.
2. Description of Related Art
Compared with single-ended signaling, differential signaling is more less prone to resistance interference and noise. Differential signaling is a method for sending two complementary signals on a pair of differential ports of a differential transmission line. For example, as shown in
Scattering parameters (S-parameters) are a useful method for analyzing external behavior of a circuit design without any regard for the content of the circuit. Often, an engineer may implement the S-parameters measured from differential ports of the circuit under different frequencies into a predetermined S-parameters model, to analyze if the circuit design is qualified. One problem is that, the predetermined S-parameters model may be created according to one kind of differential port relationships (such as shown in
The disclosure, including the accompanying drawings in which like references indicate similar elements, is illustrated by way of examples and not by way of limitation. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.
In general, the word “module,” as used hereinafter, refers to logic embodied in hardware or firmware, or to a collection of software instructions, written in a programming language, such as, for example, Java, C, or Assembly. One or more software instructions in the modules may be embedded in firmware. It will be appreciated that modules may comprised connected logic units, such as gates and flip-flops, and may comprise programmable units, such as programmable gate arrays or processors. The modules described herein may be implemented as either software and/or hardware modules and may be stored in any type of computer-readable medium or other computer storage device.
In this embodiment, the computing device 30 further includes an analysis unit 31 and a processor 32. The analysis unit 31 includes a number of function modules (detailed description is given in
The parameter reading module 311 reads the original S-parameters file 34 from the storage device 33. In one embodiment, the S-parameters include reflection coefficients, insertion loss coefficients, near-end crosstalk coefficients, and remote-end crosstalk coefficients of each port of the differential transmission line 11. The original S-parameters file 34 records S-parameter values measured from ports of the differential transmission line 11 under different signal frequencies. For example, supposing the differential transmission line 11 includes four ports numbered 1, 2, 3, and 4 as shown in
The basic port selection module 312 selects a port as a basic port from the ports of the differential transmission line 11. For example, port 1 may be selected as a basic port.
The parameter reading module 311 reads S-parameter values of remaining ports associated with the basic port from the original S-parameters file 34. For example, the values of the coefficients S12, S13, and S14 under different signal frequencies are read.
The port relationship determination module 313 selects a maximum S-parameter value on condition that a signal with a lowest frequency is input to the basic port (e.g., port 1), and determines a port directly connected with the basic port according to the maximum value. It is understood that, when the signal with the lowest frequency (such as 30 KHz) is input to the basic port (e.g., port 1), only the port (e.g., port 3) directly connected with the basic port (e.g., port 1) is enabled to make contact with the basic port (e.g., port 1). Taking
The port relationship determination module 313 selects a minimum S-parameter value on condition that the signal with a highest frequency is input to the basic port, determines a port farthest to the basic port according to the minimum S-parameter value. It is understood that, when the signal with the highest frequency (such as 20 GHz) is input to the basic port (e.g., port 1), all ports (e.g., port 2, port 3, and port 4) are enabled to make contact with the basic port (e.g., port 1), however, the farther the signal passes through, the more power the signal losses. Taking
In addition, the port relationship determination module 313 determines a port nearest to the basic port according to remaining S-parameter values. Since the port (e.g., port 3) directly connected with the basic port and the port (e.g., port 4) farthest to the basic port have been determined, then the remaining port (e.g., port 2) is determined as the port nearest to the basic port.
Moreover, the port relationship determination module 313 generates a new S-parameters file 35 according to determined relationships among the ports of the differential transmission line 11, so that the new S-parameters file 35 matches the S-parameters model 36. For example, if the S-parameters model 36 is established based on the port relationships shown in
The analysis module 314 analyzes if the design of the design of the differential transmission line 11 is qualified according to the new S-parameters file 35 and the S-parameters model 36. For example, the analysis module 314 implements the new S-parameters file 35 in the S-parameters model 36, obtains one or more analysis results, and compares the one or more analysis results with predetermined standards, to determine if the design (such as sizes, spaces of the two wires L1 and L2) of the differential transmission line 11 is qualified.
In block S301, the parameter reading module 311 reads the original S-parameters file 34 from the storage device 33. As mentioned above, the S-parameters include reflection coefficients, insertion loss coefficients, near-end crosstalk coefficients, and remote-end crosstalk coefficients of each port of the differential transmission line 11. For example, supposing the differential transmission line 11 includes four ports numbered 1, 2, 3, and 4 as shown in
In block S303, the basic port selection module 312 selects a port as a basic port from the ports of the differential transmission line 11. For example, the basic port selection module 312 may select port 1 as a basic port.
In block S305, the parameter reading module 311 reads S-parameter values of remaining ports associated with the basic port from the original S-parameters file 34. For example, the values of the coefficients S12, S13, and S14 under different signal frequencies are read.
In block S307, the port relationship determination module 313 selects a maximum S-parameter value on condition that a signal with a lowest frequency is input to the basic port (e.g., port 1). As mentioned above, when the signal with the lowest frequency (such as 30 KHz) is input to the basic port (e.g., port 1), only the port (e.g., port 3) directly connected with the basic port (e.g., port 1) is enabled to make contact with the basic port (e.g., port 1). Taking
In block S309, the port relationship determination module 313 determines a port directly connected with the basic port according to the maximum value. For example, if the S13 has the maximum value on condition that the signal with the lowest frequency of 30 KHz is input to port 1, port 3 is determined as the port directly connected with port 1.
In block S311, the port relationship determination module 313 selects a minimum S-parameter value on condition that the signal with a highest frequency is input to the basic port. As mentioned above, when the signal with the highest frequency (such as 20 GHz) is input to the basic port (e.g., port 1), all ports (e.g., port 2, port 3, and port 4) are enabled to make contact with the basic port (e.g., port 1), however, the farther the signal passes through, the more power the signal losses. Taking
In block S313, the port relationship determination module 313 determines a port farthest to the basic port according to the minimum S-parameter value. For example, if S14 has the minimum value on condition that the signal with the highest frequency 20 GHz is input to port 1, port 4 is determined as the port farthest to port 1.
In block S315, the port relationship determination module 313 determines a port nearest to the basic port according to remaining S-parameters. For example, as mentioned above, port 3 is determined as the port directly connected with port 1, then the rest port 2 is determined as the port nearest to port 1.
In block S317, the port relationship determination module 313 generates a new S-parameters file 35 according to determined relationships among the ports of the differential transmission line 11, so that the new S-parameters file 35 matches the S-parameters model 36. For example, as mentioned above, if the S-parameters model 36 is established based on the port relationships shown in
In block S319, the analysis module 314 analyzes if the design of the design of the differential transmission line 11 is qualified according to the new S-parameters file 35 and the S-parameters model 36. For example, the analysis module 314 implements the new S-parameters file 35 in the S-parameters model 36, obtains one or more analysis results, and compares the one or more analysis results with predetermined standards, to determine if the design, such as sizes, spaces of the two wires L1 and L2 of the differential transmission line 11 shown in
Although certain inventive embodiments of the present disclosure have been specifically described, the present disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the present disclosure without departing from the scope and spirit of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 99120714 | Jun 2010 | TW | national |
