JPS6218748A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To reduce a noise when an output circuit is switched by providing transistor circuits having output circuits and divided into blocks on an Si substrate, and providing a power pad or grounding pad at every block. CONSTITUTION:Transistor circuits 6 have power pads 4 and grounding pads 5 at every block. When the terminal 11 of the output circuit of the circuit 6a is held at 'L', the input terminals of the circuits 6b-6e are bundled and switched. Then, they are resonated by the capacity 10 of the circuits 6b, 6c, the grounding line impedance 7b, the common grounding line impedance 8a and the grounding pin impedance 9, and a resonance waveform is transmitted through the impedance 7a to the terminal 11. The circuits 6d, 6e, 6a are common only in the impedance 9, the rate of noise generated by the switching of the circuits 6d, 6e to be transmitted to the output terminal 11 of the circuit 6a decreases. Even if the power line is divided, noise reducing effect is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power supply or grounding (hereinafter referred to as rGNDJ)
The present invention relates to a semiconductor integrated circuit device that reduces noise appearing in an output waveform by reducing common impedance of lines.

[Conventional technology]

FIG. 4 is a general layout diagram of a five-circuit configuration made on a semiconductor substrate A. In the figure, 1 is a power supply pad, 2 is a GND pad, and 3a to 3d are transistor circuits connected to the power supply pad 1 and the GND pad 2.

-゛Figure 5 is a circuit diagram corresponding to Figure 4, where 4 is a power supply,
5 is GND. Further, 63 to 6d are transistor circuits corresponding to the transistor circuits 3a to 3d in FIG. 4, each having an output circuit composed of at least two MOSFETs. 7a and 7b are the impedances of the GND lines of the output circuits of the transistor circuits 63 to 6d, and each impedance is the impedance 8 of the common GND line.
and GND5 through impedance 9 of the GND pin. A capacitor 10 is parasitic to the output point of each transistor circuit 6a to 6d, and is parasitic connected to GND5. 11 is an output terminal of the output circuit of the transistor circuit 6a.

Next, the operation of this device will be explained using FIG.

The output circuit of the transistor circuit 6a is maintained at "L" output, and the input terminals (not shown) of the other transistor circuits 6b to 6e are bundled to output rLJ to rHJ or r
'Switch from HJ output to rLJ output. At this time, the capacitor 10 is simultaneously charged and discharged, and resonance occurs in the impedances 7b and 8.9, resulting in noise.

This noise appears at the output terminal 11 of the output circuit of the transistor circuit 6a.

FIG. 6 (81 and fb) is a waveform diagram showing an example of the output waveform 12 of the switching transistors 6b to 6e and the output waveform 13 of the transistor circuit 6a maintained at the rLJ output.

[Problem that the invention seeks to solve]

Since the conventional semiconductor integrated circuit device is configured as described above, the amount of current flowing into the impedance of the common GND line increases in proportion to the number of circuits operating simultaneously, increasing the peak value of noise. Therefore, in order to suppress the peak value of the noise to a level that does not cause malfunctions, there are problems such as the need to limit the number of circuits that operate simultaneously.

The present invention has been made in view of the above points, and an object thereof is to obtain a semiconductor integrated circuit device that can reduce noise generated in the power supply line or GND line of an output circuit during switching of the output circuit. There is a particular thing.

[Means for solving problems]

In order to achieve such an object, the present invention includes a transistor circuit having an output circuit and divided into a plurality of blocks on a semiconductor substrate, and each block is provided with a power supply pad or a ground pad. be.

[Effect]

In the present invention, by using a plurality of power supply pads or GND pads, the path of the current flowing from the power supply or the current flowing to GND is divided, and noise generated in the power supply line or GND line of the output circuit of the transistor circuit 6a is reduced. do.

〔Example〕

An embodiment of a semiconductor integrated circuit device according to the present invention is shown in FIG. FIG. 1 is a layout diagram on a semiconductor substrate A composed of five circuits. Transistor circuits 3a to 3e are connected to power supply pad 1, transistor circuits 3a to 3C are connected to GND buffer 2b, and transistor circuits 3d and 3e are connected to GND pad 2a.

FIG. 2 is an equivalent circuit diagram of the CMO3 circuit shown in FIG. 1. In FIG. 2, 8a is a transistor circuit 5a, 5b.
, 5c is a common GND impedance, and 8b is a common GND impedance of transistor circuits 6d and 6e. In FIG. 2, the same or equivalent parts as in FIG. 5 are given the same reference numerals.

The transistor circuits 6a, 6b, 6c have G of their output circuits.
ND line impedance? a, 7b, are connected to GND5 through common GND impedance 8a and GND pin impedance 9. transistor circuit 6
d and 6e are the impedance 7b of the GND line of the output circuit, the impedance 8b of the common GND, and the GND
It is connected to GND5 through pin impedance 9.

Next, the operation of the semiconductor integrated circuit device having such a configuration will be explained using FIG. 2. The output terminal 11 of the output circuit of the transistor circuit 6a is maintained at rLJ, and the input terminals (not shown) of the other transistor circuits 6b to 6e are bundled to convert the rLJ output to the rHJ output, or from the rHJ output to the rLJ output. When the capacitors 10 of the transistor circuits 6b and 6c are charged and discharged, resonance occurs due to the impedance 7b of the GND line, the impedance 8a of the common GND, and the impedance 9 of the GND pin. A resonant waveform is transmitted to the output terminal 11 of the output circuit of the transistor circuit 6a. Since the common impedance between the transistor circuits 6d and 5e and the transistor circuit 6a is only the impedance 9 of the GND pin, the proportion of noise generated by switching of the transistor circuits 6d and 6e being transmitted to the output terminal 11 is reduced, and the Noise in the output waveform is reduced.

Note that this noise reduction effect can be produced not only by dividing the GND line as shown in this embodiment, but also by dividing the power supply line.

FIG. 3 shows the relationship between the number of simultaneously operating circuits and power supply noise or GND noise, using the number of power supply pads or the number of GND pads used as a parameter. If the number of simultaneously operating circuits is increased, the noise will increase proportionally, but if the number of power supply pads or GND pads used is increased, the common impedance between the transistor circuits will be reduced, and the noise will be reduced. In FIG. 3, 14 indicates noise when one pad is used, 15 indicates noise when two pads are used, and 16 indicates noise when three pads are used.

In the above embodiment, the output circuits of the transistor circuits 68 to 6e are configured using CMO3) transistors, but similar effects can be obtained using N-MOS, P-MOS, and bipolar transistors.

〔Effect of the invention〕

As explained above, the present invention includes a transistor circuit on a semiconductor substrate that has an output circuit and is divided into a plurality of blocks, and each block is equipped with a power supply pad or a ground pad. Since the generated current flows from the power line or to GND through several paths, the electromotive force generated in the impedance of the power line or GND is divided, which has the effect of reducing the influence of other output circuits that cause noise on the waveform of one output circuit. There is.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing an embodiment of a semiconductor integrated circuit device according to the present invention, FIG. 2 is a circuit diagram showing the circuit,
Fig. 3 is a characteristic diagram for explaining the effect, Fig. 4 is a layout diagram showing a conventional semiconductor integrated circuit device, Fig. 5 is a circuit diagram showing the circuit, and Fig. 6 shows the output waveform in the circuit. FIG. l...Power supply pad, 2a, 2b...GND pad, 3a to 36.6a to 6e---Transistor circuit, 4...Power supply, 5...GND, 7a, 7b...・
・GND line impedance, 9a, 3b...
・Common GND impedance, 9...GND pin impedance, 10...Capacitor, 11...
...Output terminal.

Claims (1)

[Claims] 1. A semiconductor integrated circuit device comprising: a transistor circuit having an output circuit and divided into a plurality of blocks on a semiconductor substrate; each block having a power supply pad or a ground pad.