Controlled-impedance printed-circuit board (PCB) design with stack-up re-mapping
地域：
NY
NY Armonk
摘要
A controlled-impedance printed circuit board (PCB) design program allows interactive movement of features from one of the vertically-stacked layers of the design to another layer in a graphical interface. The movement either moves a region of a layer of the PCB design, or moves an entire layer in a layer-swapping operation. The program computes modified widths of circuit traces of the first layer of the controlled-impedance printed circuit board design according to an impedance control value of the controlled-impedance printed circuit board design and according to a new position of the circuit traces caused by a movement of the features of the first layer to the second layer. The program also checks for violation of reference plane requirements for critical signals and warns the designer if such a violation is present.
說明書
The present invention is related to printed circuit board (PCB) design programs, and more specifically to PCB design programs, methods and systems that provide a user-interactive ability to relocate a portion of a controlled-impedance PCB stack.
In present high-speed microelectronic circuits, controlled-impedance designs are used for signal management within printed circuit boards (PCBs), multi-chip module (MCMs) substrates and other package substrates. With the high frequencies and/or narrow pulse widths of critical signals in present-day digital circuits as well as in high-frequency analog circuits, special layout techniques including controlled signal-line impedances are typically required for routing critical signal paths to minimize reflections, impedance mismatches and coupling between signal paths, according to electromagnetic analysis techniques. Signal return paths, which may be reference planes such as power planes or dedicated signal reference planes are typically provided between signal layers to provide controlled signal path impedance and to shield overlapping signal paths from each other.
權利要求
What is claimed is:1. A computer-performed method of interacting with a printed circuit board designer using a workstation computer system modifying a controlled-impedance printed circuit board design comprising a plurality of vertically-stacked layers, the computer-performed method comprising:the workstation computer system loading the controlled-impedance printed circuit board design; the workstation computer system receiving a first user input from the printed circuit board designer directing modification of the controlled-impedance printed circuit board design by moving features of a first one of the plurality of vertically-stacked layers of the controlled-impedance printed circuit board design to a second one of the plurality of vertically-stacked layers; first displaying by the workstation computer system a first graphical representation of the controlled-impedance printed circuit board design; automatically, in response to receiving the first user input, the workstation computer system computing modified widths of circuit traces of a first layer of the controlled-impedance printed circuit board design according to an impedance control value of the controlled-impedance printed circuit board design and according to a new position of the circuit traces caused by a movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers and storing the modified widths of the circuit traces of the first layer of the controlled-impedance printed circuit board design in a representation of a second layer of the controlled-impedance printed circuit board design; automatically, in response to the first user input, detecting whether or not the first user input from the printed circuit board designer directs movement of the features such that a critical signal is missing coverage by a corresponding reference on an adjacent plane; generating a modified graphical representation of the controlled-impedance printed circuit board design according to the movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers; in response to detecting that the first user input directs movement of the features such that a critical signal is missing coverage by a corresponding reference on the adjacent plane, displaying a warning to the printed circuit board designer identifying the critical signal and a location of the missing coverage; and second displaying by the workstation computer system a second graphical representation of the controlled-impedance printed circuit board design. 2. The computer-performed method of claim 1 , wherein the first user input directs modification of the controlled-impedance printed circuit board design by swapping two entire layers of the controlled-impedance printed circuit board design. 3. The computer-performed method of claim 1 , wherein the first user input directs modification of the controlled-impedance printed circuit board design by moving the features within a region of the first layer of the controlled-impedance printed circuit board design to a second region within the second layer of the controlled-impedance printed circuit board design. 4. The computer-performed method of claim 1 , further comprising:responsive to computing modified widths of the circuit traces of the first layer of the controlled-impedance printed circuit board design, performing a design rules check on the new position of the circuit traces to determine whether or not the movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers causes a violation of design rules of the controlled-impedance printed circuit board design; responsive to the design rules check determining that the movement of the features causes a violation of the design rules, indicating the violation to the printed circuit board designer; and responsive to the design rules check determining that the movement of the features does not cause a violation of the design rules, performing the generating and the second displaying. 5. The computer-performed method of claim 1 , wherein the detecting further comprises:automatically, in response to the first user input, detecting that the critical signal has an extension beyond an end of the corresponding reference in the adjacent plane; and responsive to detecting that the critical signal has an extension beyond an end of the corresponding reference in the adjacent plane, comparing a length of the extension to a stub length maximum associated with the critical signal, and wherein the displaying a warning displays a stub length violation warning. 6. The computer-performed method of claim 1 , wherein the detecting further comprises automatically, in response to the first user input, detecting that a change in a signal reference occurs due to a critical signal crossing a change in reference planes in an adjacent layer, and wherein the displaying a warning displays a warning that a reference split has been introduced by the first user input. 7. A computer system comprising a processor for executing program instructions coupled to a memory for storing the program instructions, wherein the program instructions are program instructions for interacting with a printed circuit board designer using a workstation computer system modifying a controlled-impedance printed circuit board design comprising a plurality of vertically-stacked layers, wherein the program instructions comprise program instructions for:the workstation computer system loading the controlled-impedance printed circuit board design; the workstation computer system receiving a first user input from the printed circuit board designer directing modification of the controlled-impedance printed circuit board design by moving features of a first one of the plurality of vertically-stacked layers of the controlled-impedance printed circuit board design to a second one of the plurality of vertically-stacked layers; first displaying by the workstation computer system a first graphical representation of the controlled-impedance printed circuit board design; automatically, in response to receiving the first user input, the workstation computer system computing modified widths of circuit traces of a first layer of the controlled-impedance printed circuit board design according to an impedance control value of the controlled-impedance printed circuit board design and according to a new position of the circuit traces caused by a movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers and storing the modified widths of the circuit traces of the first layer of the controlled-impedance printed circuit board design in a representation of a second layer of the controlled-impedance printed circuit board design; automatically, in response to the first user input, detecting whether or not the first user input from the printed circuit board designer directs movement of the features such that a critical signal is missing coverage by a corresponding reference on an adjacent plane; generating a modified graphical representation of the controlled-impedance printed circuit board design according to the movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers; in response to detecting that the first user input directs movement of the features such that a critical signal is missing coverage by a corresponding reference on the adjacent plane, displaying a warning to the printed circuit board designer identifying the critical signal and a location of the missing coverage; and second displaying by the workstation computer system a second graphical representation of the controlled-impedance printed circuit board design. 8. The computer system of claim 7 , wherein the first user input directs modification of the controlled-impedance printed circuit board design by swapping two entire layers of the controlled-impedance printed circuit board design. 9. The computer system of claim 7 , wherein the first user input directs modification of the controlled-impedance printed circuit board design by moving the features within a region of the first layer of the controlled-impedance printed circuit board design to a second region within the second layer of the controlled-impedance printed circuit board design. 10. The computer system of claim 7 , further comprising:responsive to computing modified widths of the circuit traces of the first layer of the controlled-impedance printed circuit board design, performing a design rules check on the new position of the circuit traces to determine whether or not the movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers causes a violation of design rules of the controlled-impedance printed circuit board design; responsive to the design rules check determining that the movement of the features causes a violation of the design rules, indicating the violation to the printed circuit board designer; and responsive to the design rules check determining that the movement of the features does not cause a violation of the design rules, performing the generating and the second displaying. 11. The computer system of claim 7 , wherein the detecting further comprises:automatically, in response to the first user input, detecting that the critical signal has an extension beyond an end of the corresponding reference in the adjacent plane; and responsive to detecting that the critical signal has an extension beyond an end of the corresponding reference in the adjacent plane, comparing a length of the extension to a stub length maximum associated with the critical signal, and wherein the displaying a warning displays a stub length violation warning. 12. The computer system of claim 7 , wherein the detecting further comprises automatically, in response to the first user input, detecting that a change in a signal reference occurs due to a critical signal crossing a change in reference planes in an adjacent layer, andwherein the displaying a warning displays a warning that a reference split has been introduced by the first user input. 13. A computer program product comprising a computer-readable storage medium storing program instructions for execution by a general-purpose computer system, wherein the program instructions are program instructions for interacting with a printed circuit board designer using a workstation computer system modifying a controlled-impedance printed circuit board design comprising a plurality of vertically-stacked layers, wherein the program instructions comprise program instructions for:the workstation computer system loading the controlled-impedance printed circuit board design; the workstation computer system receiving a first user input from the printed circuit board designer directing modification of the controlled-impedance printed circuit board design by moving features of a first one of the plurality of vertically-stacked layers of the controlled-impedance printed circuit board design to a second one of the plurality of vertically-stacked layers; first displaying by the workstation computer system a first graphical representation of the controlled-impedance printed circuit board design; automatically, in response to receiving the first user input, the workstation computer system computing modified widths of circuit traces of a first layer of the controlled-impedance printed circuit board design according to an impedance control value of the controlled-impedance printed circuit board design and according to a new position of the circuit traces caused by a movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers and storing the modified widths of the circuit traces of the first layer of the controlled-impedance printed circuit board design in a representation of a second layer of the controlled-impedance printed circuit board design; automatically, in response to the first user input, detecting whether or not the first user input from the printed circuit board designer directs movement of the features such that a critical signal is missing coverage by a corresponding reference on an adjacent plane; generating a modified graphical representation of the controlled-impedance printed circuit board design according to the movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers; in response to detecting that the first user input directs movement of the features such that a critical signal is missing coverage by a corresponding reference on the adjacent plane, displaying a warning to the printed circuit board designer identifying the critical signal and a location of the missing coverage; and second displaying by the workstation computer system a second graphical representation of the controlled-impedance printed circuit board design. 14. The computer program product of claim 13 , wherein the first user input directs modification of the controlled-impedance printed circuit board design by swapping two entire layers of the controlled-impedance printed circuit board design. 15. The computer program product of claim 13 , wherein the first user input directs modification of the controlled-impedance printed circuit board design by moving the features within a region of the first layer of the controlled-impedance printed circuit board design to a second region within the second layer of the controlled-impedance printed circuit board design. 16. The computer program product of claim 13 , further comprising:responsive to computing modified widths of the circuit traces of the first layer of the controlled-impedance printed circuit board design, performing a design rules check on the new position of the circuit traces to determine whether or not the movement of the features of the first one of the plurality of vertically-stacked layers to the second one of the plurality of vertically-stacked layers causes a violation of design rules of the controlled-impedance printed circuit board design; responsive to the design rules check determining that the movement of the features causes a violation of the design rules, indicating the violation to the printed circuit board designer; and responsive to the design rules check determining that the movement of the features does not cause a violation of the design rules, performing the generating and the second displaying. 17. The computer program product of claim 13 , wherein the detecting further comprises automatically, in response to the first user input, detecting that a change in a signal reference occurs due to a critical signal crossing a change in reference planes in an adjacent layer, and wherein the displaying a warning displays a warning that a reference split has been introduced by the first user input. 18. The computer program product of claim 13 , wherein the detecting further comprises:automatically, in response to the first user input, detecting that the critical signal has an extension beyond an end of the corresponding reference in the adjacent plane; and responsive to detecting that the critical signal has an extension beyond an end of the corresponding reference in the adjacent plane, comparing a length of the extension to a stub length maximum associated with the critical signal, and wherein the displaying a warning displays a stub length violation warning.
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