Calibration device, semiconductor integrated circuit

Abstract

To reduce the time required for calibration while maintaining the quality of a signal.SOLUTION: A calibration device adjusts transmission characteristics between a transmission element and a reception element through a transmission line, and has: a margin determination unit that determines a margin for an evaluation criterion of an opening of an eye pattern indicating the transition of the waveform of the signal transmitted through the transmission line; a waveform information acquisition unit that acquires waveform information on the opening of the eye pattern indicating the transition of the waveform of the signal transmitted through the transmission line; and a determination unit that, according to a result of comparison between the waveform information and the margin, terminates the adjustment of the transmission characteristics.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a calibration device and a semiconductor integrated circuit. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in high-speed digital signal communication, calibration techniques are known that adjust the output impedance of an output buffer that transfers data, or the impedance of a termination resistor that is part of a memory circuit that holds data.

[0003] Furthermore, in the past, for example, a technique has been known in which a signal output from a waveform measuring device is analyzed to determine the waveform quality value of this signal, and then this value is compared with the waveform quality value at the setting value of a control signal stored in a memory unit to determine whether the waveform measuring device is pass or fail. Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional techniques described above, it takes time to perform calibration to ensure signal quality. Also, since access to the DDR memory and the like must be suspended during calibration, it is preferable to perform calibration in a short time.

[0005] In view of the above circumstances, the disclosed technology has an object to shorten the time required for calibration while maintaining signal quality. [Means for solving the problem]

[0006] The disclosed technology is a calibration device that adjusts transmission characteristics between a transmitting element and a receiving element via a transmission path, the calibration device including: a margin determination unit that determines a margin for an evaluation criterion of an opening of an eye pattern that indicates a transition of a signal waveform transmitted by the transmission path; a waveform information acquisition unit that acquires waveform information related to the opening of the eye pattern that indicates a transition of a signal waveform transmitted by the transmission path; and a determination unit that terminates adjustment of the transmission characteristics according to a comparison result between the waveform information and the margin. and an environmental information acquisition unit that acquires environmental information indicating an operating environment of the transmitting element or the receiving element, and further, fluctuation relationship information indicating a relationship between a fluctuation in the environmental information and a fluctuation in the waveform information is stored in advance, and the margin determination unit determines the margin by referring to the environmental information acquired by the environmental information acquisition unit and the previously stored fluctuation relationship information. . Effect of the Invention

[0007] This reduces the time required for calibration while maintaining signal quality. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating a configuration of a calibration device. [Diagram 2] FIG. 2 is a diagram illustrating an eye pattern. [Diagram 3] FIG. 13 is a diagram for explaining how to determine a margin. [Figure 4] 11 is a first flowchart illustrating the operation of the calibration device. [Diagram 5] 13 is a second flowchart illustrating the operation of the calibration device. [Figure 6] FIG. 1 is a diagram illustrating an example of a board on which a calibration device is mounted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings, in which: Fig. 1 is a diagram illustrating the configuration of a calibration device. The calibration device 1 of this embodiment is realized by, for example, a semiconductor integrated circuit such as an LSI (Large Scale Integration), etc. Therefore, the calibration device 1 of this embodiment can be said to be a semiconductor integrated circuit.

[0010] The calibration device 1 of this embodiment is connected to a transmitting / receiving element 20 that transmits (outputs) or receives (inputs) a signal, and adjusts the transmission characteristics between the transmitting element and the receiving element via a transmission line.

[0011] The calibration device 1 of this embodiment includes an environmental information acquisition section 10, a margin determination section 11, a characteristic value setting section 12, a waveform information acquisition section 13, and a judgment section .

[0012] The environmental information acquiring unit 10 acquires, as environmental information, information indicating an operating environment such as an internal temperature of a circuit in which the transmitting / receiving element 20 is mounted, a power supply voltage, etc. Note that the environmental information may be acquired by, for example, a control circuit mounted on a board together with the calibration device 1 and the transmitting / receiving element 20.

[0013] The margin determination unit 11 determines a margin for an evaluation criterion of an eye pattern that indicates a transition of a signal waveform outputted or inputted from the transmitting / receiving element 20, based on the environmental information. In other words, the eye pattern indicates a transition of a signal waveform transmitted through a transmission path between a transmitting element and a receiving element. The evaluation criterion of the eye pattern is, for example, a value determined by the standard of a semiconductor integrated circuit that constitutes the memory. The method of determining the margin will be described in detail later.

[0014] The characteristic value setting unit 12 sets a characteristic value. The characteristic value is a value that affects the transmission characteristics of a signal, and may have multiple values. Specifically, the characteristic value is, for example, the output impedance of the transmitting / receiving element 20, the impedance when a part of the semiconductor integrated circuit functions as a termination resistor (ODT: On Die Termination), etc.

[0015] The waveform information acquiring unit 13 acquires waveform information of a signal outputted or inputted from the transmitting / receiving element 20. Specifically, the waveform information acquiring unit 13 acquires, as waveform information, information relating to the opening of an eye pattern indicated by the signal waveform outputted or inputted from the transmitting / receiving element 20. Specifically, the information relating to the opening of the eye pattern is a level in the voltage axis direction or a level in the time axis direction.

[0016] The judgment unit 14 compares the margin determined by the margin determination unit 11 with the waveform information acquired by the waveform information acquisition unit 13, and judges whether or not the value indicated by the waveform information ensures a margin. Then, the calibration device 1 of this embodiment ends the calibration if the value indicated by the waveform information ensures a margin.

[0017] That is, the determining section 14 ends the calibration depending on the result of the comparison between the margin and the waveform information.

[0018] In this manner, in this embodiment, the margin determined based on the environmental information is compared with the value indicated by the waveform information of the signal output or input from the transmitting / receiving element 20, and the calibration is terminated when the margin is ensured. Therefore, according to this embodiment, even if there are a plurality of characteristic values, for example, processing such as analyzing the waveform information corresponding to all the characteristic values ​​is not required, and the time required for calibration can be shortened while maintaining the signal quality.

[0019] The eye pattern will be described below with reference to Fig. 2. Fig. 2 is a diagram for explaining the eye pattern.

[0020] 2 corresponds to a signal waveform outputted or inputted from the transmitting / receiving element 20. In this case, the waveform information acquiring unit 13 of the present embodiment acquires the level (value) of the opening of the eye pattern in the voltage axis direction V and the level (value) in the time axis direction t.

[0021] Next, a method for determining the margin will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining a method for determining the margin.

[0022] In this embodiment, information indicating the influence on the waveform information when the environmental information varies is acquired in advance by simulation or actual measurement. In other words, the calibration device 1 may hold variation relationship information indicating the relationship between the variation of the environmental information and the variation of the waveform information.

[0023] Fig. 3 shows the level (vertical axis) of the opening of the eye pattern in the voltage axis direction when the power supply voltage (horizontal axis) is changed. In other words, the graph shown in Fig. 3 is an example of variation relationship information showing the relationship between the variation of the environment information and the variation of the waveform information. In this embodiment, the variation relationship information may be stored as a table corresponding to the graph, or may be stored as a function.

[0024] In FIG. 3, Vmax and Vmin are the upper and lower limits of the operating range of the power supply voltage, H1 indicates the level in the voltage axis direction of the opening when the power supply voltage is at the lower limit, and H2 indicates the level in the voltage axis direction of the opening when the power supply voltage is at the upper limit.

[0025] The margin determination unit 11 of this embodiment refers to the power supply voltage Va and the fluctuation relationship information included in the environmental information acquired by the environmental information acquisition unit 10, and determines the level Ha of the opening in the voltage axis direction corresponding to the power supply voltage Va.

[0026] Then, the margin determining unit 11 of this embodiment determines the difference between the level Ha and the level H1 as the margin.

[0027] Therefore, in this case, in this embodiment, if the evaluation standard in the voltage axis direction of the opening of the eye pattern is Hc, the calibration is terminated if the level in the voltage axis direction of the opening included in the waveform information is Hc+(Ha-H1) or more.

[0028] In this embodiment, by providing a margin in this manner, it is possible to achieve the evaluation criteria of the standard even if the power supply voltage drops from Va to VVmin during operation and the level in the voltage axis direction of the opening of the eye pattern drops.

[0029] In this embodiment, the variation relationship information is stored in advance, and the margin is determined by referring to the environmental information and the variation relationship information, but this is not limited to the above. The margin determination unit 11 of this embodiment may determine the margin by multiplying the evaluation criterion by a coefficient without referring to the environmental information. In this case, since it is not necessary to obtain the environmental information, the configuration of the calibration device 1 can be simplified.

[0030] 3, information indicating the relationship between the fluctuation of the power supply voltage and the fluctuation of the level of the opening of the eye pattern in the voltage axis direction is taken as an example of the fluctuation relationship information, but is not limited to this. In this embodiment, information indicating the relationship between the fluctuation of the power supply voltage and the fluctuation of the level of the opening of the eye pattern in the time axis direction may be included in the fluctuation relationship information.

[0031] Next, the operation of the calibration device 1 of this embodiment will be described with reference to Figures 4 and 5. Figure 4 is a first flowchart illustrating the operation of the calibration device.

[0032] When the calibration device 1 of this embodiment receives an instruction to start calibration, the environment information acquisition unit 10 acquires environment information (step S401). Next, the calibration device 1 determines a margin by referring to the environment information and the variation relationship information using the margin determination unit 11 (step S402).

[0033] Next, the calibration device 1 sets a characteristic value by the characteristic value setting unit 12 (step S403). Note that the characteristic value setting unit 12 of the present embodiment may hold a plurality of values ​​as the characteristic value to be set, and only needs to select and set one value from the plurality of values.

[0034] Next, the calibration device 1 acquires waveform information of the signal outputted from or inputted to the transmitting / receiving element 20 by the waveform information acquiring unit 13 (step S404).

[0035] Next, the calibration device 1 causes the determining unit 14 to compare the waveform information with the margin and determine whether the margin is secured (step S405).

[0036] Specifically, for example, the determining unit 14 determines whether or not the level in the voltage axis direction of the opening of the eye pattern included in the waveform information is equal to or greater than a value obtained by adding a margin to the evaluation criterion of this eye pattern.

[0037] If the margin is not ensured in step S405, the calibration device 1 returns to step S403 and causes the characteristic value setting unit 12 to set another characteristic value.

[0038] Furthermore, in step S406, if the margin is secured, the calibration device 1 ends the calibration.

[0039] The characteristic value setting unit 12 of this embodiment may hold information indicating the characteristic value to be preferentially set according to the environmental information. In this case, the characteristic value setting unit 12 may refer to the environmental information and set the characteristic value with the highest priority in step S403. In this way, the waveform information can be quickly put into a state in which a margin is secured.

[0040] Next, another example of the operation of the calibration device 1 of this embodiment will be described with reference to Fig. 5. Fig. 5 is a second flowchart illustrating the operation of the calibration device.

[0041] The processing from step S501 to step S505 in FIG. 5 is similar to the processing from step S401 to step S405 in FIG. 4, and therefore the description thereof will be omitted.

[0042] If the margin is not ensured in step S505, the calibration device 1 determines whether or not the processes in and after step S504 have been performed for all combinations of a plurality of characteristic values ​​held by the characteristic value setting unit 12 (step S506).

[0043] In step S506, if processing has not been performed for all combinations, the calibration device 1 returns to step S503 and sets characteristic values ​​for combinations that have not been processed.

[0044] In step S506, when all the combinations have been processed, the calibration device 1 notifies an error (step S507) and ends the process. The error may be notified in any form. For example, the error may be notified to a higher-level device of the calibration device 1.

[0045] Also, in this embodiment, instead of notifying an error in step S507, the optimum combination of all the combinations may be set as the characteristic value, and the calibration may be terminated.

[0046] 5, an optimal combination of characteristic values ​​may be specified in advance by simulation, actual measurement evaluation, or the like, and the optimal characteristic values ​​may be set in the initial setting of the characteristic values. In this way, it is possible to increase the possibility that a margin will be secured with the initially set characteristic values. Furthermore, in this embodiment, if a margin is secured with the initial setting of the characteristic values, the calibration ends at that point, and therefore the time required for the calibration can be reduced.

[0047] Next, a usage scene of the calibration device 1 of this embodiment will be described with reference to FIG.

[0048] FIG. 6 is a diagram showing an example of a board on which a calibration device is mounted. The printed circuit board 30 includes semiconductor packages 31 and 33 .

[0049] The semiconductor package 31 includes an output buffer 32 that transmits a signal. The semiconductor package 33 includes an input buffer 34 and the calibration device 1.

[0050] The input buffer 34 receives the signal output from the output buffer 32. In the calibration device 1, the signal output from the input buffer 34 is input to the waveform information acquisition unit 13. That is, in the example of Fig. 6, the input buffer 34 corresponds to the transmitting / receiving element 20 in Fig. 1.

[0051] In the printed circuit board 30, the output buffer 32 and the input buffer 34 are connected by a transmission path 35 formed of a wiring pattern on the printed circuit board 30. A signal transmitted from the output buffer 32 is transmitted to the input buffer 34 through the transmission path 35.

[0052] In this example of the printed circuit board 30, the calibration device 1 acquires environmental information of the semiconductor package 33 and determines the margin. In this case, the calibration device 1 sets the value of a termination resistor realized by a part of the semiconductor package 33 as a characteristic value. Then, the calibration device 1 acquires waveform information from the signal waveform received by the input buffer 34, and determines whether or not a margin is secured in the waveform information.

[0053] If the margin is ensured, the calibration device 1 ends the calibration, and if the margin is not ensured, the calibration device 1 changes the characteristic value and performs the calibration again.

[0054] At this time, the characteristic value may be the output impedance of the output buffer 32. In this case, the semiconductor package 33 may instruct the semiconductor package 31 to set the output impedance of the output buffer 32 by a control circuit or the like implemented in the semiconductor package.

[0055] In this embodiment, by using the calibration device 1 in this manner, it is possible to maintain the quality of the signal transmitted between the semiconductor package 31 and the semiconductor package 33 while shortening the time required for calibration.

[0056] 6, the calibration device 1 is mounted in the semiconductor package 33, but this is not limiting. The calibration device 1 may be mounted in the semiconductor package 31. In this case, the output buffer 32 corresponds to the transmitting / receiving element 20 in FIG. 1, and the calibration device 1 may acquire waveform information from the signal waveform of the signal output from the output buffer 32.

[0057] Although the present invention has been described above based on the embodiments, the present invention is not limited to the requirements shown in the above embodiments. These points can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of symbols]

[0058] 1 Calibration device 10 Environmental Information Acquisition Department 11 Margin Determination Section 12. Characteristic value setting section 13 Waveform information acquisition section 14 Judgment section 20 Transmitting and receiving element 30 Printed Circuit Board 31, 33 Semiconductor packages 32 Output Buffers 34 Input Buffer 35 Transmission Line [Prior art documents] [Patent documents]

[0059] [Patent Document 1] JP 2009-192542 A

Claims

1. A calibration device for adjusting a transmission characteristic between a transmitting element and a receiving element via a transmission path, comprising: a margin determination unit that determines a margin for an evaluation criterion of an opening of an eye pattern that indicates a transition of a signal waveform transmitted through the transmission line; a waveform information acquiring unit that acquires waveform information related to an opening of an eye pattern that indicates a transition of a signal waveform transmitted through the transmission line; a determination unit that terminates the adjustment of the transmission characteristics according to a comparison result between the waveform information and the margin; An environmental information acquisition unit that acquires environmental information indicating an operating environment of the transmitting element or the receiving element, Furthermore, fluctuation relationship information indicating a relationship between a fluctuation in the environmental information and a fluctuation in the waveform information is stored in advance, The margin determination unit is A calibration device that determines the margin by referring to the environmental information acquired by the environmental information acquisition unit and the variation relationship information that is stored in advance.

2. The waveform information regarding the opening includes a value in a voltage axis direction and a value in a time axis direction, The determination unit is 2. The calibration device according to claim 1, wherein the adjustment is terminated when a margin for the evaluation criterion is ensured in the value included in the waveform information.

3. The margin determination unit is 3. The calibration device according to claim 1, wherein the margin is a value obtained by multiplying the evaluation standard by a predetermined coefficient.

4. A setting unit that sets a characteristic value that affects the transmission characteristic of the transmission path, The calibration device according to claim 1 , wherein the setting unit changes the characteristic value when a margin for the evaluation criterion is not ensured in a value included in the waveform information.

5. The characteristic values ​​are:

5. The calibration device according to claim 4, further comprising at least one of an output impedance of the transmitting element and an impedance of a termination resistor which is a part of a circuit in which the transmitting element or the receiving element is mounted.

6. A semiconductor integrated circuit that adjusts a transmission characteristic between a transmitting element and a receiving element via a transmission path, a margin determination unit that determines a margin for an evaluation criterion of an opening of an eye pattern that indicates a transition of a signal waveform transmitted through the transmission line; a waveform information acquiring unit that acquires waveform information related to an opening of an eye pattern that indicates a transition of a signal waveform transmitted through the transmission line; a determination unit that terminates the adjustment of the transmission characteristics according to a comparison result between the waveform information and the margin; An environmental information acquisition unit that acquires environmental information indicating an operating environment of the transmitting element or the receiving element, Furthermore, fluctuation relationship information indicating a relationship between a fluctuation in the environmental information and a fluctuation in the waveform information is stored in advance, The margin determination unit is A semiconductor integrated circuit that determines the margin by referring to the environmental information acquired by the environmental information acquisition unit and the variation relationship information that is stored in advance.

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