JP2009180502A - Integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an integrated circuit detecting a ground bounce. <P>SOLUTION: This integrated circuit is mounted on a circuit board, and is provided with a terminal for detecting a ground bounce by arranging a differential amplifier circuit inside the integrated circuit for inputting ground voltage of the circuit board and ground voltage inside the integrated circuit, and for outputting output of this ground bounce detecting part to an external part of the integrated circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an integrated circuit mounted on a circuit board, and more particularly to detection of ground bounce inside an integrated circuit.

  FIG. 4 is a diagram showing an example of a conventional integrated circuit. The integrated circuit 10 is an integrated circuit such as an FPGA that is mounted on a circuit board and performs various signal processing. A power supply voltage Vcc is supplied to a power supply terminal of the integrated circuit 10 through a power supply line formed on the circuit board. The ground terminal of the integrated circuit 10 is connected to the ground voltage GND1 on the circuit board, and the ground state is maintained. The signal terminal of the integrated circuit 10 is connected to a signal line on the circuit board and used for signal input / output.

  GND2 is a ground voltage inside the integrated circuit 10. Originally, the ground voltage GND2 is the same as the ground voltage GND1 on the circuit board, and is considered to be 0V. However, a resistance component and an inductance component exist in the wiring from the chip of the integrated circuit 10 to the power supply terminal or the ground terminal. Therefore, the ground voltage GND2 in the integrated circuit 10 varies according to the magnitude of the current flowing to the ground terminal with respect to the ground voltage GND1 on the circuit board. This variation corresponds to a change in the power supply voltage Vcc and the ground voltage GND1 when viewed from the chip of the integrated circuit 10, and is referred to as ground bounce (power supply voltage variation).

  In particular, as the number of signals output at the same timing, that is, the simultaneous switching operation (SSO) increases, the current consumed instantaneously increases. As a result, ground bounce appears prominently, causing malfunction of the internal circuit or mismatch between the external signal level and the internal signal level, which may cause malfunction of the integrated circuit 10.

  In order to avoid such influence of ground bounce due to simultaneous switching, many integrated circuit manufacturers provide design guidelines such as limiting the number of used pins and limiting output slew rate for simultaneous switching. The following non-patent document 1 is an example of a design guideline related to ground bounce.

Japanese Patent Laid-Open No. 5-122047 Actel, “(Application Notes) ProASICPLUS SSO and Pin Placement Guidelines”, [online], June 2006, [searched January 9, 2008], Internet <URL: http://www.actel.com/techdocs /an.aspx>

  Conventionally, however, there has been no comprehensive design validity evaluation method for ground bounce in circuit board design including the operation of an integrated circuit and the number and arrangement of bypass capacitors. In addition, when the operation of the integrated circuit is confirmed and an operation failure is found, it is not easy to determine whether the cause of the operation failure is due to ground bounce.

  An object of the present invention is to realize an integrated circuit capable of detecting ground bounce by outputting a signal indicating ground bounce inside the integrated circuit.

In order to achieve the above object, in claim 1 of the present invention, in an integrated circuit mounted on a circuit board,
A ground bounce detector for detecting ground bounce inside the integrated circuit;
A terminal for outputting the output of the ground bounce detector to the outside of the integrated circuit;
Is provided.

The integrated circuit according to claim 1, wherein the ground bounce detection unit includes:
It is a differential amplifier to which the ground voltage of the circuit board and the ground voltage inside the integrated circuit are inputted.

The integrated circuit according to claim 1, wherein the ground bounce detection unit includes:
A differential amplifier to which a ground voltage of the circuit board and a ground voltage inside the integrated circuit are input;
A determination circuit that outputs a signal indicating the noise level of the ground bounce according to the output of the differential amplifier;
It is characterized by having.

  According to a fourth aspect of the present invention, in the integrated circuit according to any one of the first to third aspects, the terminal is provided on an upper surface portion of the integrated circuit.

  Thus, by providing the terminal for outputting a signal indicating the ground bounce in the integrated circuit, an integrated circuit capable of detecting the ground bounce can be realized. Moreover, the influence of simultaneous switching can be evaluated by detecting the ground bounce.

  Hereinafter, an integrated circuit of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of an integrated circuit according to the present invention. The integrated circuit 10 is an integrated circuit such as an FPGA that is mounted on a circuit board and performs various signal processing. A power supply voltage Vcc is supplied to a power supply terminal of the integrated circuit 10 through a power supply line formed on the circuit board. GND1 is a ground voltage on the circuit board, and GND2 is a ground voltage inside the integrated circuit 10. The signal terminal of the integrated circuit 10 is connected to a signal line on the circuit board and used for signal input / output.

  A ground bounce detector 10 is provided inside the integrated circuit 10. The ground bounce detection unit 10 includes a differential amplifier 10a. A ground voltage GND1 on the circuit board and a ground voltage GND2 inside the integrated circuit 10 are input to the differential amplifier 10a. The differential amplifier 10a outputs a signal obtained by amplifying the voltage difference between the ground voltage GND1 and the ground voltage GND2. The output of the differential amplifier 10a indicates the state of ground bounce inside the integrated circuit 10. The output of the differential amplifier 10a changes according to the size of the ground bounce. When the output of the differential amplifier 10a is large, it means that the ground bounce is large. When the output of the differential amplifier 10a is small, it means that the ground bounce is small.

  It is desirable to obtain GND1 on the circuit board that is input to the differential amplifier from a sufficiently stable point that is less affected by the operation of the integrated circuit. For example, instead of acquiring from the GND 1 from directly under the integrated circuit 10, it is considered to be drawn from a point outside the area immediately below the integrated circuit 10.

  The terminal 20 is a terminal to which the output of the differential amplifier 10a is connected. The output of the differential amplifier 10a can be detected from the outside of the integrated circuit 10 as a ground bounce signal (S1).

  Thus, by outputting the ground bounce signal S1 to the outside of the integrated circuit, the ground bounce of the integrated circuit 10 can be detected from the outside. As a result, in the circuit board design including the operation of the integrated circuit 10 and the number and arrangement of the bypass capacitors, it is possible to evaluate the overall design validity with respect to the ground bounce. Further, when an operation failure of the integrated circuit 10 is found, it becomes easy to determine whether the cause of the operation failure is due to ground bounce.

  Possible situations where ground bounce detection and simultaneous switching evaluation are required include circuit board design, debugging, and maintenance. In particular, during debugging, engineers actually spend a lot of time isolating the cause of malfunction. The integrated circuit of the present invention contributes to shortening the time required for such work, which is a great merit for engineers.

  Note that the terminal 20 may have the same form as other terminals of the integrated circuit, or may have a special form different from the other terminals. Providing the terminal 20 on the upper surface of the package of the integrated circuit 10 has an advantage that an engineer can easily apply a tester or the like.

  FIG. 2 is a diagram showing another embodiment of an integrated circuit according to the present invention. The integrated circuit of this embodiment is substantially obtained by adding a determination circuit 11b to the configuration of the first embodiment.

  Reference numeral 11 denotes a ground bounce detector provided in the integrated circuit 10. The ground bounce detection unit 11 includes a differential amplifier 11a and a determination circuit 11b. Since the differential amplifier 11a is the same as the differential amplifier 10a of the above embodiment, the description thereof is omitted.

  The output of the differential amplifier 11a is input to the determination circuit 11b. The determination circuit 11b monitors the output of the differential amplifier 11a and performs GO / NO-GO determination of the ground bounce noise level. That is, the determination circuit 11b outputs a signal indicating GO when the output from the differential amplifier 11a is equal to or lower than a predetermined voltage value, and outputs a signal indicating NO-GO when the output from the differential amplifier 11a is equal to or higher than the predetermined voltage value. . These signal outputs may be digital signals. Further, it may be a multi-bit signal. The output of the determination circuit 11b is output to the outside of the integrated circuit 10 through the terminal 20 as a signal (S2) indicating the noise level of ground bounce.

  The terminal 20 is a terminal to which the output of the determination circuit 11b is connected. The noise level signal S2 can be detected from the outside of the integrated circuit 10 via the terminal 20. When the noise level signal S2 is a signal of a plurality of bits, the number of terminals 20 may be plural according to the bit width.

  The noise level signal S2 can be used for BIT (Built-in Test) of the circuit board. If the noise level signal S2 is used for BIT or the like, it can be used for detecting a failure caused by ground bounce.

  FIG. 3 is a diagram showing another embodiment of an integrated circuit according to the present invention. The integrated circuit of this embodiment is substantially obtained by changing the determination circuit 11b of the second embodiment to an AD converter 12b.

  Reference numeral 12 denotes a ground bounce detector provided in the integrated circuit 10. The ground bounce detector 12 includes a differential amplifier 12a and an AD converter 12b. Since the differential amplifier 12a is the same as the differential amplifiers 10a and 11a of the first embodiment and the second embodiment, description thereof is omitted.

  The output of the differential amplifier 12a is input to the AD converter 12b. The AD converter 12b AD-converts the output voltage from the differential amplifier 12a, and outputs digital data corresponding to the ground bounce noise level. The output of the AD converter 12b is output to the outside of the integrated circuit 10 through the terminal 20 as a signal (S3) indicating the noise level of ground bounce.

  The terminal 20 is a terminal to which the output of the AD converter 12b is connected. The noise level signal S3 can be detected from the outside of the integrated circuit 10 via the terminal 20. The number of terminals 20 may be plural according to the bit width of the noise level signal S3.

  By performing AD conversion on the output of the differential amplifier 12a by the AD converter 12b, the noise level of the ground bounce can be grasped in detail.

  In the present embodiment, the output of the AD converter 12b is output to the outside of the integrated circuit 10 as it is, but a determination circuit may be further provided in the subsequent stage of the AD converter 12b. The determination circuit monitors the digital data output from the AD converter 12b, and outputs a signal indicating GO when the noise level is equal to or lower than a predetermined value and NO-GO when the noise level is higher than the predetermined value. Output. If the AD converter 12b and the determination circuit are used in combination, there is an advantage that the reference value of GO / NO-GO can be set finely.

The present invention can be applied to various types of integrated circuits including FPGAs.
The terminal 20 corresponds to the terminal of the present invention.

FIG. 1 is a diagram showing an embodiment of an integrated circuit according to the present invention. FIG. 2 is a diagram showing another embodiment of the integrated circuit according to the present invention. FIG. 3 is a diagram showing another embodiment of the integrated circuit according to the present invention. FIG. 4 is a diagram showing an example of a conventional integrated circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Integrated circuit 10 Ground bounce detection part 10a Differential amplifier 11 Ground bounce detection part 11a Differential amplifier 11b Determination circuit 12 Ground bounce detection part 12a Differential amplifier 12b AD converter 20 Terminal GND1 Ground voltage on a circuit board GND2 Integrated circuit inside Ground voltage F / F flip-flop

Claims (4)

In an integrated circuit mounted on a circuit board,
A ground bounce detector for detecting ground bounce inside the integrated circuit;
A terminal for outputting the output of the ground bounce detector to the outside of the integrated circuit;
An integrated circuit characterized in that is provided. The ground bounce detector is
The integrated circuit according to claim 1, wherein the integrated circuit is a differential amplifier to which a ground voltage of the circuit board and a ground voltage inside the integrated circuit are input. The ground bounce detector is
A differential amplifier to which a ground voltage of the circuit board and a ground voltage inside the integrated circuit are input;
A determination circuit that outputs a signal indicating the noise level of the ground bounce according to the output of the differential amplifier;
The integrated circuit according to claim 1, comprising:   The integrated circuit according to claim 1, wherein the terminal is provided on an upper surface portion of the integrated circuit.

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