CN106610468B - Scan chain, and scan chain construction method and device - Google Patents
Scan chain, and scan chain construction method and device Download PDFInfo
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- CN106610468B CN106610468B CN201510688566.2A CN201510688566A CN106610468B CN 106610468 B CN106610468 B CN 106610468B CN 201510688566 A CN201510688566 A CN 201510688566A CN 106610468 B CN106610468 B CN 106610468B
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Abstract
The invention provides a scan chain, a scan chain construction method and a scan chain construction device, relates to the technical field of integrated circuits, and solves the problem that the fault diagnosis precision of the scan chain in the prior art is not high. The method comprises the following steps: extracting all scanning units in the circuit to form a scanning unit set; acquiring the correlation of any two scanning units in the scanning unit set; creating a scan chain set, wherein each scan chain in the scan chain set is an empty scan chain; and sequentially extracting a scanning chain of a scanning unit from the scanning unit set, wherein the scanning chain is placed in the scanning chain set, and deleting the extracted scanning unit from the scanning unit set until each scanning chain in the scanning chain set reaches the maximum chain length of the scanning chain, wherein the correlation degree of any two scanning units in the same scanning chain is less than a correlation degree threshold value. The invention is suitable for constructing the scanning chain in a large-scale digital chip circuit with a complex structure.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a scan chain, a scan chain construction method and a scan chain construction device.
Background
Generally, the integrated circuit is mainly verified (Pre-silicon Verification) before being delivered to a chip to ensure the correctness of the chip. With the increasing design scale and the increasing complexity of chips, the time of pre-silicon verification is restricted, so that the pre-silicon verification of the chips is difficult to be fully performed, and the chips after tape-out have faults. Therefore, Post-silicon Debug (Post-silicon Debug) is required to be performed on the chip after tape-out to find and locate the error left in the chip, and further ensure the correctness of the chip.
The scan chain area of the chip accounts for about 15% -30% of the whole chip, and is one of the most prone to failure. According to statistics, the number of faults of the scan chain accounts for about 50% of the total number of faults of the chip, and the faults of the scan chain are main factors influencing the yield of the chip. Therefore, when a scan chain fault occurs, how to quickly and accurately locate the scan chain fault and find the reason of the fault is the key to improve the yield of the chip and shorten the product cycle of the chip.
The scan chain structure that may appear in the prior art is shown in fig. 1 and fig. 2, as shown in fig. 1, the fan-in scan cells a, b, c, d belonging to the same scan cell o are located on the same scan chain; as shown in fig. 2, fan-out scan cells a, b, c, d belonging to the same scan cell o are located on the same scan chain. With the scan chain structure, when a scan chain fails, it is difficult to accurately locate the failed scan cell in the scan chain.
In the process of implementing the invention, the inventor finds that at least the following technical problems exist in the prior art:
in a scan chain structure constructed in the prior art, a plurality of scan cells fanned into the same scan cell may be allocated to the same scan chain, and a plurality of scan cells fanned out by the same scan cell may be allocated to the same scan chain, which results in low failure diagnosis precision of the scan chain.
Disclosure of Invention
The scan chain, the scan chain construction method and the scan chain construction device can improve the fault diagnosis precision of the scan chain.
In a first aspect, the present invention provides a scan chain construction method, including:
extracting all scanning units in the circuit to form a scanning unit set;
acquiring the correlation of any two scanning units in the scanning unit set;
creating a scan chain set, wherein each scan chain in the scan chain set is an empty scan chain;
and sequentially extracting a scanning chain of a scanning unit from the scanning unit set, wherein the scanning chain is placed in the scanning chain set, and deleting the extracted scanning unit from the scanning unit set until each scanning chain in the scanning chain set reaches the maximum chain length of the scanning chain, wherein the correlation degree of any two scanning units in the same scanning chain is less than a correlation degree threshold value.
In a second aspect, the present invention provides a scan chain constructing apparatus, including:
the scanning unit extracting module is used for extracting all scanning units in the circuit to form a scanning unit set;
a correlation obtaining module, configured to obtain a correlation between any two scanning units in the scanning unit set;
the device comprises an empty scan chain creating module, a scan chain setting module and a scan chain setting module, wherein the empty scan chain creating module is used for creating a scan chain set, and each scan chain in the scan chain set is an empty scan chain;
and the scan chain construction module is used for sequentially extracting a scan chain of a scan unit from the scan unit set, putting the scan unit into the scan chain set, and deleting the extracted scan unit from the scan unit set until each scan chain in the scan chain set reaches the maximum chain length of the scan chain, wherein the correlation degree of any two scan units in the same scan chain is less than a correlation degree threshold value.
In a third aspect, the present invention provides a scan chain, wherein the correlation degree of any two scan cells in the scan chain is less than the correlation degree threshold.
The scan chain, the scan chain construction method and the device provided by the embodiment of the invention acquire the correlation degree of any two scan cells in a scan cell set consisting of all scan cells in a circuit, sequentially extract one scan cell from the scan cell set and put the scan chain in the created empty scan chain set, and delete the extracted scan cell from the scan cell set until each scan chain in the scan chain set reaches the maximum chain length of the scan chain, wherein the correlation degree of any two scan cells in the same scan chain is smaller than a correlation threshold value. Compared with the prior art, the invention can distribute the scanning units with large relevance to different scanning chains, avoid distributing the scanning units fanned into the same scanning unit to the same scanning chain as far as possible, and avoid distributing the scanning units fanned out by the same scanning unit to the same scanning chain, thereby improving the fault diagnosis precision of the scanning chains.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIGS. 1 and 2 are schematic diagrams of scan chain structures in the prior art;
FIG. 3 is a flowchart of a scan chain construction method according to an embodiment of the present invention;
FIG. 4 is a detailed flowchart of step S22 in the scan chain construction method according to another embodiment of the present invention;
FIG. 5 is a detailed flowchart of step S24 in the scan chain construction method according to another embodiment of the present invention;
fig. 6 is a schematic structural diagram of a scan chain constructed based on fan-in circuit logic in a scan chain construction method according to another embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a scan chain constructed based on fanout circuit logic in a scan chain construction method according to another embodiment of the present invention;
fig. 8 and fig. 9 are schematic structural diagrams of scan chains constructed based on physical positions of scan cells in a scan chain construction method according to another embodiment of the present invention;
fig. 10 is a schematic structural diagram of a scan chain constructing apparatus according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a scan chain construction apparatus according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
An embodiment of the present invention provides a scan chain construction method, as shown in fig. 3, where the scan chain construction method includes:
and S11, extracting all the scanning units in the circuit to form a scanning unit set.
The scan unit may be a flip-flop or a latch with a scan function, but is not limited thereto.
And S12, acquiring the correlation of any two scanning units in the scanning unit set.
The correlation degrees of any two scanning units can be obtained by calculation according to the fan-in correlation degree, the fan-out correlation degree and the physical position correlation degree of any two scanning units.
The correlation degree of the two scanning units is a quantized value, which is used to reflect the close degree of the overall relationship of the two scanning units in the logical structure and the physical position. The fan-in correlation degree reflects the degree of closeness of the relationship of two scanning units which are fanned into the same scanning unit on the logic structure; the fan-out correlation degree reflects the degree of closeness of the relationship of two scanning units fanned out from the same scanning unit on the logic structure; the physical position correlation reflects how closely the two scanning units are in relation to each other in physical position.
S13, creating a scan chain set, wherein each scan chain in the scan chain set is an empty scan chain.
Wherein, the empty scan chain, that is, the scan chain, contains 0 scan cells.
S14, sequentially extracting a scan chain of a scan unit from the scan unit set, placing the scan unit into the scan chain set, and deleting the extracted scan unit from the scan unit set until each scan chain in the scan chain set reaches the maximum chain length of the scan chain, wherein the correlation degree of any two scan units in the same scan chain is smaller than the correlation degree threshold value.
The correlation threshold and the maximum chain length of the scan chain are preset; the initial value of the correlation threshold value can be an experience value set manually, and can also be an average value of the sum of the correlations of any two scanning units in the scanning unit set; the maximum chain length of the scan chain can be the number of the scan units in the scan unit set divided by the number of the chip test pins in the circuit.
The scan chain construction method provided by the embodiment of the invention is characterized in that the correlation degree of any two scan cells in a scan cell set consisting of all scan cells in a circuit is obtained, one scan chain of the scan cell set which is placed into the created empty scan chain set is sequentially extracted from the scan cell set, and the extracted scan cell is deleted from the scan cell set until all the scan chains in the scan chain set reach the maximum chain length of the scan chain, wherein the correlation degree of any two scan cells in the same scan chain is smaller than a correlation threshold value. Compared with the prior art, the invention can distribute the scanning units with large relevance to different scanning chains, avoid distributing the scanning units fanned into the same scanning unit to the same scanning chain as far as possible, and avoid distributing the scanning units fanned out by the same scanning unit to the same scanning chain, thereby improving the fault diagnosis precision of the scanning chains.
The embodiment of the invention also provides a scan chain construction method, which comprises the following specific flows:
and S21, extracting all the scanning units in the circuit to form a scanning unit set G.
The number of the scanning units in the scanning unit set G is L, and L is an integer greater than or equal to 2.
And S22, acquiring the correlation of any two scanning units in the scanning unit set G.
Specifically, as shown in fig. 4, the step S22 may include the following steps:
s221, obtaining the fan-in correlation degree of the scanning units a and b according to the logic relation of any two scanning units a and b in the scanning unit set G.
If the scanning units a and b belong to the same scanning unit o, the fan-in correlation degree R of the scanning units a and bFan in<a,b>The number M of the scanning units fanning into the same scanning unit o is in positive correlation function, that is, the more the scanning units fanning into the same scanning unit o, the larger the M value, and then RFan in<a,b>The greater the value of (A); conversely, the fewer scanning units fanned into the same scanning unit o, the smaller the M value, and then RFan in<a,b>The smaller the value of (c);
the positive correlation means that the two variables have the same variation direction, and when one variable changes from large to small or from small to large, the other variable also changes from large to small or from small to large. For example, when the dependent variable Y and the independent variable X are positive correlation functions with each other, the dependent variable Y changes in the same direction as the independent variable X changes.
Alternatively, RFan in<a,b>May be equal to M.
If the scanning units a and b do not belong to the same scanning unit o, the fan-in correlation degree R of the scanning units a and bFan in<a,b>Is 0.
S222, obtaining the fan-out correlation degree of the scanning units a and b according to the logic relation of any two scanning units a and b in the scanning unit set G.
If scan cells a and b belong to the same scan cell o's fan-out, then the fan-out correlation R of scan cells a and bFan out<a,b>The number M of the scanning units fanned out by the same scanning unit o is in a negative correlation function, that is, the more the scanning units fanned out by the same scanning unit o, the larger the value of M, and RFan out<a,b>The smaller the value of (c); conversely, the fewer scanning units fanned out by the same scanning unit o, the smaller the M value, and then RFan out<a,b>The greater the value of (A);
the negative correlation means that the two variables change in opposite directions, and when one variable changes from large to small or from small to large, the other variable changes from small to large or from large to small. For example, when the dependent variable Y and the independent variable X are negative correlation functions with each other, the dependent variable Y changes in the opposite direction as the independent variable X changes.
Alternatively, RFan out<a,b>May be equal to M _ max/M, where M _ max represents the maximum number of scan cells fanned out by the same scan cell o in the circuit.
If the scanning units a and b do not belong to the fan-out of the same scanning unit o, the fan-out phases of the scanning units a and bDegree of closure RFan out<a,b>Is 0.
S223, acquiring the physical position correlation degree of the scanning units a and b according to the physical positions of any two scanning units a and b in the scanning unit set G.
Wherein, if the constraint requirement of a certain area on the physical position is more strict, the value of the physical position correlation degree is larger; if the constraint requirement of a certain area on the physical position is looser, the smaller the value of the physical position correlation degree is.
Wherein, according to the physical position of the scanning unit, the circuit can be divided into k areas, each area is allocated with a corresponding physical position correlation value, and k is an integer greater than or equal to 1.
Optionally, the physical location correlation W assigned to each regiondomain_iI can be equal to i, i is an integer and the value range is that i is more than or equal to 1 and less than or equal to k. Wherein, domain _ i represents the ith area.
Wherein, the larger the value of i is, the more severe the constraint requirement of the domain _ i on the physical position is; the smaller the value of i, the more relaxed the constraint requirement on the physical location of the area domain _ i is represented.
If the scanning units a and b are both located in the ith area, the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to the physical position dependence W of the area in which they are locateddomain_i；
If the scanning units a and b are respectively located in different areas, the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to 1.
And S224, calculating the correlation degree of the scanning units a and b according to the obtained fan-in correlation degree, fan-out correlation degree and physical position correlation degree of the scanning units a and b.
Specifically, the correlation R < a, b > of the scanning units a and b is calculated as follows:
s23, creating a scan chain set, wherein each scan chain in the scan chain set is an empty scan chain.
Specifically, N empty scan chains are created, a scan chain set F is formed, and a correlation threshold value and a maximum chain length of the scan chains are set, wherein N is an integer greater than or equal to 1.
Wherein the empty scan chain, i.e. the scan chain, comprises 0 scan cells; the initial value of the correlation threshold value can be the average value of the sum of the correlations R < a, b > of all the scanning units a and b in the scanning unit set G; the maximum chain length of the scan chain can be the number L of the scan units in the scan unit set G divided by the number of the chip test pins in the circuit.
S24, sequentially extracting a scan chain of a scan cell from the scan cell set G, and placing the scan cell into the scan chain set F, and deleting the extracted scan cell from the scan cell set G until each scan chain in the scan chain set F reaches the maximum chain length of the scan chain, wherein the correlation between any two scan cells in the same scan chain is less than the correlation threshold.
Specifically, as shown in fig. 5, the step S24 may include the following steps:
s241, extracting the first scan cell in the scan cell set G, and placing the first scan cell in one of the empty scan chains F in the scan chain set F.
S242, one scanning unit G in the scanning unit set G is sequentially selected, if the correlation degree of the scanning unit G and any one scanning unit in the scanning chain is smaller than the threshold value of the correlation degree, the scanning unit G is placed in the scanning chain f, and the scanning unit G in the scanning unit G is deleted; otherwise, the next scanning unit in the scanning unit set G is continuously selected.
S243, judging whether the scan chain f reaches the maximum chain length of the scan chain, and if so, executing the step S244; if the maximum chain length of the scan chain is not reached, step S245 is executed.
S244, judging whether an empty scan chain exists in the scan chain set F, and if so, returning to execute the step S241; if there is no empty scan chain, step S247 is executed.
S245, judging whether all the scanning units in the scanning unit set G are selected, if not, returning to execute the step S242; if both are selected, go to step S246.
S246, increase the correlation threshold, and return to step S242.
And S247, constructing a scanning chain of the circuit according to the finally obtained scanning chain set.
According to the final scan chain set, the number of the scan cells allocated to each scan chain, which scan cells are allocated and the sequence of the allocated scan cells can be known.
Specifically, a scan path file may be generated according to the finally obtained scan chain set, the generated scan path file is imported into an EDA tool, and the scan chain of the circuit is constructed by the EDA tool. And after the scan chain is constructed, performing timing evaluation on the circuit by using a timing analysis tool. If the result of the timing analysis is not ideal, for example, the delay of the data path of the high-speed module in the chip is too large, the correlation between the physical positions of any two scan cells a and b in the scan cell set G can be adjusted, the correlation between any two scan cells a and b in the scan cell set G can be recalculated, and then the scan chain structure can be reconstructed according to the above process until a better timing analysis result is obtained.
According to the scan chain construction method provided by the above embodiment, the structure of the finally obtained scan chain constructed based on the fan-in circuit logic is as shown in fig. 6; the structure of the scan chain constructed based on the logic of the fan-out circuit is shown in FIG. 7; the structure of the scan chain constructed based on the physical location of the scan cells is shown in fig. 8 or fig. 9, wherein the structure of the scan chain constructed based on the physical location of the scan cells shown in fig. 9 is the preferred scan chain structure.
As can be seen from fig. 6, 7, 8, and 9, the scan chain construction method provided by the embodiment of the present invention can avoid allocating scan cells fanned into the same scan cell to the same scan chain as much as possible, and avoid allocating scan cells fanned out by the same scan cell to the same scan chain, and allocate scan cells in close physical relationship to the same scan chain as much as possible, so as to improve the fault diagnosis accuracy of the scan chain.
An embodiment of the present invention provides a scan chain constructing apparatus, as shown in fig. 10, where the scan chain constructing apparatus includes:
and the scanning unit extracting module 11 is used for extracting all the scanning units in the circuit to form a scanning unit set.
The scan unit may be a flip-flop or a latch with a scan function, but is not limited thereto.
A correlation obtaining module 12, configured to obtain a correlation between any two scanning units in the scanning unit set.
The correlation degrees of any two scanning units can be obtained by calculation according to the fan-in correlation degree, the fan-out correlation degree and the physical position correlation degree of any two scanning units.
And an empty scan chain creation module 13, configured to create a scan chain set, where each scan chain in the scan chain set is an empty scan chain.
Wherein, the empty scan chain, that is, the scan chain, contains 0 scan cells.
And the scan chain construction module 14 is configured to sequentially extract a scan chain of a scan unit from the scan unit set, the scan chain being placed in the scan chain set, and delete the extracted scan unit from the scan unit set until each scan chain in the scan chain set reaches the maximum chain length of the scan chain, where a correlation between any two scan units in the same scan chain is less than a correlation threshold.
The correlation threshold and the maximum chain length of the scan chain are preset; the initial value of the correlation threshold value can be an experience value set manually, and can also be an average value of the sum of the correlations of any two scanning units in the scanning unit set; the maximum chain length of the scan chain can be the number of the scan units in the scan unit set divided by the number of the chip test pins in the circuit.
The scan chain construction device provided by the embodiment of the invention obtains the correlation degree of any two scan cells in a scan cell set consisting of all scan cells in a circuit, sequentially extracts a scan chain of a scan cell from the scan cell set and puts the scan chain into the created empty scan chain set, and deletes the extracted scan cell from the scan cell set until each scan chain in the scan chain set reaches the maximum chain length of the scan chain, wherein the correlation degree of any two scan cells in the same scan chain is less than the correlation threshold value. Compared with the prior art, the invention can distribute the scanning units with large relevance to different scanning chains, avoid distributing the scanning units fanned into the same scanning unit to the same scanning chain as far as possible, and avoid distributing the scanning units fanned out by the same scanning unit to the same scanning chain, thereby improving the fault diagnosis precision of the scanning chains.
Further, as shown in fig. 11, the correlation obtaining module 12 may include:
a fan-in correlation obtaining sub-module 121, configured to obtain a fan-in correlation R of the scanning units a and b according to a logical relationship between any two scanning units a and b in the scanning unit setFan in<a,b>；
A fan-out correlation degree obtaining submodule 122, configured to obtain a fan-out correlation degree R of any two scanning units a and b in the scanning unit set according to a logical relationship between the scanning units a and bFan out<a,b>；
A physical position correlation degree obtaining sub-module 123 for obtaining the physical position correlation degree W of the scanning units a and b according to the physical positions of the scanning units a and bdomain_i<a,b>The circuit is divided into k areas according to the physical positions of the scanning units, each area has corresponding physical position correlation, domain _ i is the ith area, wherein i is an integer and the value range is that i is more than or equal to 1 and less than or equal to k, and k is a positive integer more than or equal to 2;
a correlation operator module 124 for calculating the fan-in correlation R according to the scan units a and bFan in<a,b>Fan-out correlation RFan out<a,b>Degree of correlation with physical position Wdomain_i<a,b>Calculating the correlation R of the scanning units a and b<a,b>Wherein, in the step (A),
alternatively, if the scanning units a and b belong to the same scanning unit o, the fan-in correlation degree obtaining sub-module 121 obtains the fan-in correlation degrees R of the scanning units a and bFan in<a,b>The number M of the scanning units fanning into the same scanning unit o is in positive correlation function, that is, the more the scanning units fanning into the same scanning unit o, the larger the M value, and then RFan in<a,b>The greater the value of (A); conversely, the fewer scanning units fanned into the same scanning unit o, the smaller the M value, and then RFan in<a,b>The smaller the value of (c);
if the scanning units a and b do not belong to the same scanning unit o, the fan-in correlation degree obtaining submodule obtains the fan-in correlation degree R of the scanning units a and bFan in<a,b>Is 0.
Optionally, if the scan cells a and b belong to the fan-out of the same scan cell o, the fan-out correlation degree obtaining sub-module 122 obtains the fan-out correlation degree R of the scan cells a and bFan out<a,b>The number M of the scanning units fanned out by the same scanning unit o is in a negative correlation function, that is, the more the scanning units fanned out by the same scanning unit o, the larger the value of M, and RFan out<a,b>The smaller the value of (c); conversely, the fewer scanning units fanned out by the same scanning unit o, the smaller the M value, and then RFan out<a,b>The greater the value of (A);
if the scanning units a and b do not belong to the fan-out of the same scanning unit o, the fan-out correlation degree obtaining submodule obtains the fan-out correlation degree R of the scanning units a and bFan out<a,b>Is 0 or 0.
Alternatively, if the scanning units a and b are located in the ith area, the physical position correlation degree obtaining sub-module 123 obtains the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to the physical position dependence W of the area in which they are locateddomain_i(ii) a Wherein each timePhysical location correlation W of individual region assignmentsdomain_iMay be equal to i, i ═ 1,2, …, k. Wherein, the larger the value of i is, the more severe the constraint requirement of the domain _ i on the physical position is; the smaller the value of i, the more relaxed the constraint requirement on the physical location of the area domain _ i is represented. (ii) a
If the scanning units a and b are respectively located in different areas, the physical position correlation degree obtaining sub-module obtains the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to 1.
Further, the scan chain constructing module 14 is further configured to increase the correlation threshold when a scan chain in the scan chain set does not reach the maximum chain length of the scan chain, and sequentially extract a scan unit from the current scan unit set and put the scan unit into the scan chain until each scan chain in the scan chain set reaches the maximum chain length of the scan chain.
The embodiment of the invention also provides a scan chain, and the correlation degree of any two scan units in the scan chain is smaller than the threshold value of the correlation degree.
Optionally, the correlation R < a, b > of any two scanning units a and b is calculated according to the following formula:
wherein R isFan in<a,b>For the fan-in correlation of scan cells a and b, RFan out<a,b>For fan-out correlation of scan cells a and b, Wdomain_i<a,b>Is the physical position dependence of the scanning units a and b.
Fan-in correlation R of the scanning units a and bFan in<a,b>Fan-out correlation RFan out<a,b>And physical location correlation Wdomain_i<a,b>The definition of (c) can be referred to the scan chain construction method embodiments described above.
Optionally, the correlation threshold is an average value of a sum of correlations of any two scanning units in all scanning units in the circuit.
Further, all scan cells in the scan chain do not belong to a fan-in scan cell of the same scan cell, and/or all scan cells in the scan chain do not belong to a fan-out scan cell of the same scan cell, and/or all scan cells in the scan chain are located in the same region of a circuit.
Wherein the circuit may be divided into k regions according to the physical location of the scanning unit.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (8)
1. A scan chain construction method, comprising:
extracting all scanning units in the circuit to form a scanning unit set;
acquiring the correlation of any two scanning units in the scanning unit set;
creating a scan chain set, wherein each scan chain in the scan chain set is an empty scan chain;
sequentially extracting a scanning chain of a scanning unit from the scanning unit set, wherein the scanning chain is placed in the scanning chain set, and deleting the extracted scanning unit from the scanning unit set until each scanning chain in the scanning chain set reaches the maximum chain length of the scanning chain, wherein the correlation degree of any two scanning units in the same scanning chain is smaller than a correlation degree threshold value;
wherein the obtaining the correlation degree of any two scanning units in the scanning unit set comprises:
obtaining the fan-in correlation degree R of the scanning units a and b according to the logic relation of any two scanning units a and b in the scanning unit setFan in<a,b>Wherein, if the scanning units a and b belong to the same scanning unit o, the fan-in correlation degree R of the scanning units a and bFan in<a,b>The number M of the scanning units fanning into the same scanning unit o is in positive correlation function, if the scanning units a and b do not belong to the same scanning unit o, the fanning correlation degree R of the scanning units a and bFan in<a,b>Is 0;
obtaining the fan-out correlation degree R of the scanning units a and b according to the logic relation of any two scanning units a and b in the scanning unit setFan out<a,b>Wherein, if the scanning units a and b belong to the fan-out of the same scanning unit o, the fan-out correlation degree R of the scanning units a and bFan out<a,b>The number M of the scanning units fanned out by the same scanning unit o is in a negative correlation function, if the scanning units a and b do not belong to the fanning out of the same scanning unit o, the fanning-out correlation degree R of the scanning units a and bFan out<a,b>Is 0;
acquiring the physical position correlation degree W of the scanning units a and b according to the physical positions of the scanning units a and bdomain_i<a,b>The circuit is divided into k areas according to the physical positions of the scanning units, each area has corresponding physical position correlation, domain _ i is the ith area, wherein i is an integer and the value range is that i is more than or equal to 1 and less than or equal to k, and k is an integer more than or equal to 1;
fan-in correlation R according to scan cells a and bFan in<a,b>Fan-out correlation RFan out<a,b>Degree of correlation with physical position Wdomain_i<a,b>Calculating the correlation R of the scanning units a and b<a,b>Wherein, in the step (A),
2. the method according to claim 1, wherein the physical position correlation degree W of the scanning units a and b is obtained according to the physical positions of the scanning units a and bdomain_i<a,b>The method comprises the following steps:
if the scanning units a and b are both located in the ith area, the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to the physical position dependence W of the area in which they are locateddomain_i；
If the scanning units a and b are respectively located in different areas, the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to 1.
3. The method of claim 1, wherein sequentially extracting a scan chain of a scan cell from the set of scan cells into the set of scan chains and deleting the extracted scan cell from the set of scan cells until each scan chain of the set of scan chains reaches a scan chain maximum chain length comprises:
and if the scan chain in the scan chain set does not reach the maximum chain length of the scan chain, increasing the correlation threshold, and sequentially extracting a scan unit from the current scan unit set and putting the scan unit into the scan chain until each scan chain in the scan chain set reaches the maximum chain length of the scan chain.
4. A scan chain construction apparatus, comprising:
the scanning unit extracting module is used for extracting all scanning units in the circuit to form a scanning unit set;
a correlation obtaining module, configured to obtain a correlation between any two scanning units in the scanning unit set;
the device comprises an empty scan chain creating module, a scan chain setting module and a scan chain setting module, wherein the empty scan chain creating module is used for creating a scan chain set, and each scan chain in the scan chain set is an empty scan chain;
the scan chain building module is used for sequentially extracting a scan chain of a scan unit from the scan unit set, putting the scan unit into the scan chain set, and deleting the extracted scan unit from the scan unit set until each scan chain in the scan chain set reaches the maximum chain length of the scan chain, wherein the correlation degree of any two scan units in the same scan chain is smaller than a correlation degree threshold value;
the correlation obtaining module is further configured to obtain a fan-in correlation R of the scanning units a and b according to a logical relationship between any two scanning units a and b in the scanning unit setFan in<a,b>Wherein, if the scanning units a and b belong to the same scanning unit o, the fan-in correlation degree R of the scanning units a and bFan in<a,b>The number M of the scanning units fanning into the same scanning unit o is in positive correlation function, if the scanning units a and b do not belong to the same scanning unit o, the fanning correlation degree R of the scanning units a and bFan in<a,b>Is 0; and acquiring fan-out correlation degree R of the scanning units a and b according to the logic relation of any two scanning units a and b in the scanning unit setFan out<a,b>Wherein, if the scanning units a and b belong to the fan-out of the same scanning unit o, the fan-out correlation degree R of the scanning units a and bFan out<a,b>The number M of the scanning units fanned out by the same scanning unit o is in a negative correlation function, if the scanning units a and b do not belong to the fanning out of the same scanning unit o, the fanning-out correlation degree R of the scanning units a and bFan out<a,b>Is 0; and acquiring the physical position correlation degree W of the scanning units a and b according to the physical positions of the scanning units a and bdomain_i<a,b>The circuit is divided into k areas according to the physical positions of the scanning units, each area has corresponding physical position correlation, domain _ i is the ith area, wherein i is an integer and the value range is that i is more than or equal to 1 and less than or equal to k, and k is an integer more than or equal to 1; fan-in correlation R according to scan cells a and bFan in<a,b>Fan-out correlation RFan out<a,b>Degree of correlation with physical position Wdomain_i<a,b>Calculating the correlation of the scanning units a and bR<a,b>Wherein, in the step (A),
5. the apparatus according to claim 4, wherein the physical position correlation degree obtaining sub-module obtains the physical position correlation degree W of the scanning units a and b if the scanning units a and b are located in the ith areadomain_i<a,b>Equal to the physical position dependence W of the area in which they are locateddomain_i；
If the scanning units a and b are respectively located in different areas, the physical position correlation degree obtaining sub-module obtains the physical position correlation degree W of the scanning units a and bdomain_i<a,b>Equal to 1.
6. The apparatus according to claim 4, wherein the scan chain constructing module is further configured to increase the correlation threshold when a scan chain in the scan chain set does not reach the maximum chain length of the scan chain, and sequentially extract a scan cell from the current scan cell set and put the scan cell into the scan chain until each scan chain in the scan chain set reaches the maximum chain length of the scan chain.
7. A scan chain, wherein the correlation degree of any two scan cells in the scan chain is less than the correlation degree threshold, and the correlation degree R < a, b > of any two scan cells a and b is calculated according to the following formula:
wherein R isFan in<a,b>For the fan-in correlation of scan cells a and b, RFan out<a,b>For fan-out correlation of scan cells a and b, Wdomain_i<a,b>Is the physical position correlation of the scanning units a and b;
if the scanning units a andb belongs to the fan-in of the same scanning unit o, the fan-in correlation degree R of the scanning units a and bFan in<a,b>The number M of the scanning units fanning into the same scanning unit o is in positive correlation function, if the scanning units a and b do not belong to the same scanning unit o, the fanning correlation degree R of the scanning units a and bFan in<a,b>Is 0;
if scan cells a and b belong to the same scan cell o's fan-out, then the fan-out correlation R of scan cells a and bFan out<a,b>The number M of the scanning units fanned out by the same scanning unit o is in a negative correlation function, if the scanning units a and b do not belong to the fanning out of the same scanning unit o, the fanning-out correlation degree R of the scanning units a and bFan out<a,b>Is 0.
8. The scan chain of claim 7, wherein all scan cells in the scan chain do not belong to a fan-in scan cell of the same scan cell, and/or all scan cells in the scan chain do not belong to a fan-out scan cell of the same scan cell, and/or all scan cells in the scan chain are located in the same region of a circuit.
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