JP2004146674A - Semiconductor integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit capable of reducing the number of pads for a power supply or ground while suppressing the propagation of noise from a digital circuit to an analog circuit or from the analog circuit to the digital circuit. <P>SOLUTION: The semiconductor integrated circuit is provided with an analog circuit for performing analog signal processing, a digital circuit for performing digital signal processing, a power supply pad shared by the analog circuit and the digital circuit, an inductor arranged on a power supply route to the digital circuit, and a power supply line for supplying power supplied through the power supply pad directly to the analog circuit and supplying the power to the digital circuit through the inductor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor integrated circuit including an analog circuit that performs analog signal processing and a digital circuit that performs digital signal processing.
[0002]
[Prior art]
Conventionally, when a logic circuit (hereinafter, referred to as a digital circuit) and an analog circuit that handles analog signals and digital signals such as an A / D converter and a D / A converter are mounted on the same chip, the operation of the digital circuit is performed. In order to prevent the influence (interference) of the noise generated in the circuit on the analog circuit, separate power supply systems (power supply voltage, ground) are used in each circuit.
[0003]
Further, also in the analog circuits, a digital circuit that handles them and handles digital signals is used as a common power supply system with the digital circuits to prevent the analog circuits from affecting the analog circuits. .
[0004]
Meanwhile, in recent years, the power supply voltage of digital circuits has been reduced in order to reduce current consumption or prevent device deterioration due to miniaturization of processes. On the other hand, the power supply voltage of the analog circuit cannot be lowered for securing the performance such as securing the dynamic range, and the analog circuit and the digital circuit constituting the analog circuit are driven by the same power supply voltage. Accordingly, the power supply system of the digital circuit and the power supply system of the digital circuit in the analog circuit cannot be shared, and it is necessary to secure the power supply system of the digital circuit separately from the power supply system of the digital circuit.
[0005]
As described above, an analog circuit such as an A / D converter or a D / A converter includes an analog circuit that performs analog signal processing and a digital circuit that performs digital signal processing. It is driven by a power supply voltage having the same potential as the driving power supply voltage.
[0006]
First, when designing a semiconductor integrated circuit that incorporates an analog circuit and a digital circuit driven by the same potential power supply voltage, the power supply pins of the semiconductor integrated circuit are shared by the analog circuit and the digital circuit described above. Further, it is considered that a power supply path from a power supply pin to an analog circuit and a digital circuit is also shared. Since the same applies to the ground side, the power supply side will be described here.
[0007]
Here, a problem in configuring such a power supply path is that noise generated in the digital circuit propagates to the analog circuit via the power supply path. This noise is generated in the digital circuit due to an instantaneous power fluctuation such as a clock pulse in the digital circuit.
[0008]
In order to suppress the propagation of the noise, it is necessary to branch a power supply path from a power supply pin shared by the analog circuit and the digital circuit to the analog circuit and the digital circuit for the analog circuit and the digital circuit. However, if the branch point is on the circuit side, noise is likely to propagate, so that the power supply path is preferably branched near the power supply pin.
[0009]
Here, as a method of connecting a bonding wire used for electrical connection between a pin of a semiconductor integrated circuit and a pad on a substrate of the semiconductor integrated circuit, a double bonding is used to connect two bonding wires to the same bonding space. A connection method is conventionally known (for example, see Patent Document 1).
[0010]
Therefore, although the power supply pin itself is shared by the analog circuit and the digital circuit, the power supply path is independent of the power supply path for the analog circuit and the power supply path for the digital circuit using the above-described double bonding technique. Consider providing two power supply paths.
[0011]
FIG. 1 is a diagram illustrating a semiconductor integrated circuit including an analog circuit power supply path and a digital circuit power supply path, and an analog circuit ground path and a digital circuit ground path.
[0012]
Here, the semiconductor integrated circuit 100 shown in FIG. 1 includes a signal communication path through which various signals propagate, and the signal communication path and the like are described below by focusing on a power supply path and a ground path. Is not shown in FIG.
[0013]
FIG. 1 shows a power supply path 110 from the power supply pin 111 to the digital circuit 120 and the analog circuit 130, and a ground path 140 from the ground pin 141 to the digital circuit 120 and the analog circuit 130.
[0014]
First, the power supply path 110 will be described.
[0015]
The power supply path 110 includes a power supply pin 111, two bonding wires 112 and 113 double-bonded to the power supply pin 111, a digital circuit power supply path 114 connected to the bonding wire 112, and a bonding wire 113. And an analog circuit power supply path 115 connected thereto. The digital circuit power supply path 114 includes a digital circuit power supply pad 114a and a digital circuit power supply line 114b. The analog circuit power supply path 115 includes an analog circuit power supply pad 115a and an analog circuit power supply line 115b. It is composed of
[0016]
The power W supplied to the power supply pin 111 shown in FIG. 1 is supplied to the digital circuit power supply pad 114a and the analog circuit power supply via two bonding wires 112 and 113 which are double-bonded to the power supply pin 111. Each is supplied to the pad 115a. The power Wd supplied to the digital circuit power supply pad 114a is supplied to the digital circuit 120 via the digital circuit power supply pad 114a and the digital circuit power supply line 114b. The power Wa supplied to the analog circuit power supply pad 115a is supplied to the analog circuit 130 via the analog circuit power supply pad 115a and the analog circuit power supply line 115b.
[0017]
The power supply pin 111 which is a branch point of the power supply path 110 is located farthest from the power supply path 110 on the power supply path 110 extending from the power supply pin 111 to the analog circuit 130 and the digital circuit 120. As a result, in the power supply path 110, the noise propagation path from the analog circuit 130 to the digital circuit 120 is the longest, so that noise generated in the digital circuit 120 is transmitted to the analog circuit through the power supply path 110. Propagation is suppressed.
[0018]
Here, a bonding wire generally has an inductance, and it has been conventionally known that the inductance suppresses the propagation of noise via the bonding wire.
[0019]
Therefore, the noise generated in the digital circuit 120 is suppressed not only by the above-described branch of the power supply path 110, but also by the inductance of the two bonding wires 112 and 113, in addition to the suppression of the propagation of the noise. Noise is suppressed from propagating from the digital circuit power supply path 114 to the power supply pin 111, and from the power supply pin 111 to the analog circuit power supply path 115.
[0020]
An isolation region 116, which is a predetermined space, is provided between the digital circuit power supply pad 114a and the analog circuit power supply pad 115a.
[0021]
The role played by the separation region 116 will be described below.
[0022]
As described above, the power supply voltage supplied from the power supply pin 111 forms one power supply system supplied to the digital circuit 120 via the bonding wire 112, the digital circuit power supply pad 114a, and the digital circuit power supply line 114b, and It is also supplied to the ESD protection circuit and the like near the digital circuit power supply pad 114a. Similarly, the power supply voltage supplied from the power supply pin 111 forms another power supply system supplied to the analog circuit 130 via the bonding wire 113, the analog circuit power supply pad 115a, and the analog circuit power supply line 115b, It is also supplied to an ESD protection circuit and the like near the analog circuit power supply pad 115a. As described above, these power supply voltages become the power supply voltages of the circuits near the respective power supply pads, and also become the bias voltages of the substrate or the well.
[0023]
Here, the same power supply voltage is normally applied to each ESD protection circuit and the like. For example, when the power supply voltage fluctuates in one power supply line or the like, a substrate formed in the semiconductor integrated circuit, There is a possibility that a parasitic thyristor constituted by a well, a diffusion layer, or the like is turned on, causing latch-up. In order to prevent such a latch-up phenomenon, it is necessary to increase the distance between the elements so that the parasitic thyristor does not turn on. Therefore, the isolation region 116 as shown in FIG. 1 serves to prevent this latch-up phenomenon.
[0024]
Next, the ground path 140 will be described.
[0025]
The ground path 140 is connected to a ground pin 141, two bonding wires 142 and 143 double-bonded to the ground pin 141, a digital circuit ground path 145 connected to the bonding wire 143, and a bonding wire 142. And an analog circuit ground path 144. The digital circuit ground path 145 includes a digital circuit ground pad 145a and a digital circuit ground line 145b. The analog circuit ground path 144 includes an analog circuit ground pad 144a and an analog circuit ground line 144b. Have been. The digital circuit 120 and the analog circuit 130 are connected to the ground pin 141 by the ground path 140.
[0026]
Here, similarly to the above-described power supply path 110, the noise generated in the digital circuit 120 is also suppressed from propagating to the analog circuit 130 in the ground path 140.
[0027]
[Patent Document 1]
JP-A-2000-208582 (paragraph number 0008-0018, FIGS. 1 and 6)
[0028]
[Problems to be solved by the invention]
Here, the semiconductor integrated circuit 100 shown in FIG. 1 is provided with an analog circuit power supply path for suppressing noise generated in the digital circuit from propagating to the analog circuit via the power supply path. And a digital circuit power supply path. The same applies to the ground side. Here, the power supply side will be described.
[0029]
As a result, at least two pads for power supply, a digital circuit power supply pad and an analog circuit power supply pad, are required.
[0030]
Further, in designing a semiconductor integrated circuit, if it is intended to further suppress noise propagation by arranging a power pad for digital circuits and a power pad for analog circuits at a predetermined interval from each other, as described above, An isolation region is required between the power supply pad and the analog circuit power supply pad.
[0031]
Here, for example, in designing a semiconductor integrated circuit, if the above-mentioned separation region is set to a space corresponding to one pad, if this separation region is counted as one pad, the semiconductor integrated circuit needs to supply power. The number of pads is three.
[0032]
Thus, in the semiconductor integrated circuit 100 shown in FIG. 1, the number of pads required for power supply is large, and the substrate of the semiconductor integrated circuit requires a large area by the number of pads. There is.
[0033]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a semiconductor integrated circuit that requires a small number of power supply or ground pads while suppressing noise generated in a digital circuit from propagating to an analog circuit. Aim.
[0034]
[Means for Solving the Problems]
A first semiconductor integrated circuit of the present invention that achieves the above object has an analog circuit that performs analog signal processing, a digital circuit that performs digital signal processing, a power supply pad shared by the analog circuit and the digital circuit, An inductor disposed on a power supply path to the digital circuit, and power supplied from the outside via the power supply pad is supplied directly to the analog circuit and the digital circuit is supplied via the inductor. And a power supply line for supplying the power.
[0035]
In the first semiconductor integrated circuit of the present invention, the power supply pad is shared by the analog circuit and the digital circuit. Therefore, for example, in the semiconductor integrated circuit 100 shown in FIG. Then, it becomes possible to replace the three necessary power supply pads with at least one power supply pad.
[0036]
In the first semiconductor integrated circuit of the present invention, since the inductor is arranged on the power supply path to the digital circuit, noise generated in the digital circuit propagates to the analog circuit via the power supply path. Is suppressed.
[0037]
According to another embodiment of the present invention, there is provided a semiconductor integrated circuit comprising: an analog circuit for performing analog signal processing; a digital circuit for performing digital signal processing; and a ground pad shared by the analog circuit and the digital circuit. And an inductor disposed on a ground path from the digital circuit to the ground pad, the ground pad and the analog circuit being directly connected, and the ground pad and the digital circuit being connected via the inductor. And a ground line.
[0038]
In the second semiconductor integrated circuit of the present invention, the ground pad is shared between the analog circuit and the digital circuit. Therefore, for example, in the semiconductor integrated circuit 100 shown in FIG. In the second semiconductor integrated circuit of the present invention, at least one ground pad is required instead of the three ground pads required.
[0039]
Also, in the second semiconductor integrated circuit of the present invention, since the inductor is arranged on the ground path from the digital circuit to the ground pad, noise generated in the digital circuit propagates to the analog circuit via the ground path. That has been suppressed.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the first semiconductor integrated circuit of the present invention will be described.
[0041]
FIG. 2 is a diagram showing one embodiment of the first semiconductor integrated circuit of the present invention.
[0042]
FIG. 2 shows a power supply path 210 and a ground path 240 of the semiconductor integrated circuit 200.
[0043]
In the power supply path 210 of the semiconductor integrated circuit 200 shown in FIG. 2, the power supply pad 213 is shared by the digital circuit 220 and the analog circuit 230. On the other hand, the circuit configuration of the ground path 240 in the semiconductor integrated circuit 200 is the same as the circuit configuration of the ground path 140 in the semiconductor integrated circuit 100 shown in FIG. Therefore, for the semiconductor integrated circuit 200 shown in FIG. 2, description of the ground path 240, which is the same point as that of the semiconductor integrated circuit 100 shown in FIG. 1, is omitted, and the semiconductor integrated circuit shown in FIG. The power supply path 210 which is different from the circuit 100 will be described.
[0044]
Here, the semiconductor integrated circuit shown in FIG. 2 includes a signal communication path through which various signals propagate. However, since the signal communication path and the like are not relevant to the description of the present invention, FIG. Has been omitted. The same applies to FIGS. 3 and 4 described later.
[0045]
The power W supplied to the power supply pin 211 shown in FIG. 2 is supplied to the power supply pad 213 via the bonding wire 212. The power W supplied to the power supply pad 213 is supplied directly to the analog circuit 230 via the power supply pad 213 and the power supply line 214, and is supplied to the digital circuit 220 via the inductor 215.
[0046]
The inductor 215 suppresses noise generated in the digital circuit 220 from propagating to the analog circuit 230 via the power supply line 214.
[0047]
As described above, by sharing the power supply pad 213 between the digital circuit 220 and the analog circuit 230 while suppressing the propagation of noise using the inductor 215, the two in the semiconductor integrated circuit 100 shown in FIG. In the semiconductor integrated circuit 200 shown in FIG. 2, only one power supply pad 213 is required for three power supply pads, which is required when three isolation regions are counted as one pad.
[0048]
Here, the inductor 215 is formed of a spiral conductor provided on a wiring layer of the substrate 201 of the semiconductor integrated circuit 200. Generally, in a semiconductor integrated circuit, an empty area often exists in an upper layer portion of the wiring layer. In designing the semiconductor integrated circuit 200, the inductor 215 is provided by using the empty area without increasing the area of the substrate 201 of the semiconductor integrated circuit 200. Further, the inductance of the inductor 215 has a value corresponding to the number of turns of the spiral conductor constituting the inductor 215. Therefore, in designing the semiconductor integrated circuit 200, the inductance of the inductor 215 is set to an optimal value for suppressing the propagation of noise by setting the number of turns of the conductor to an appropriate value. This method of installing the inductor is the same for FIGS. 3 and 4 described later.
[0049]
Next, an embodiment of a second semiconductor integrated circuit of the present invention will be described.
[0050]
FIG. 3 is a diagram showing one embodiment of the second semiconductor integrated circuit of the present invention.
[0051]
FIG. 3 shows a power supply path 310 and a ground path 340 of the semiconductor integrated circuit 300.
[0052]
The ground path 340 of the semiconductor integrated circuit 300 shown in FIG. 3 shares the ground pad 343 with the digital circuit 320 and the analog circuit 330. On the other hand, the circuit configuration of the power supply path 310 in the semiconductor integrated circuit 300 is the same as the circuit configuration of the power supply path 110 in the semiconductor integrated circuit 100 shown in FIG. Therefore, for the semiconductor integrated circuit 300 shown in FIG. 3, the description of the power supply path 310 which is the same as that of the semiconductor integrated circuit 100 shown in FIG. 1 is omitted, and the semiconductor integrated circuit 300 shown in FIG. The ground path 340 that is different from the integrated circuit 100 will be described.
[0053]
The analog circuit 330 shown in FIG. 3 is connected directly to the ground pad 343 by the ground line 344 via the inductor 345, and the digital circuit 320 is connected to the ground pin 341 by the bonding wire 342. You.
[0054]
The above-described inductor 345 suppresses noise generated in the digital circuit 320 from propagating to the analog circuit 330 via the ground line 344.
[0055]
As described above, by sharing the ground pad 343 between the digital circuit 320 and the analog circuit 330 while suppressing the propagation of noise using the inductor 345, two of the semiconductor integrated circuits 100 shown in FIG. In the semiconductor integrated circuit 300 shown in FIG. 3, only one ground pad 343 is required instead of the three ground pads required when the separation region is counted as one pad.
[0056]
Next, a third embodiment of the semiconductor integrated circuit of the present invention will be described.
[0057]
FIG. 4 is a diagram showing one embodiment of the third semiconductor integrated circuit of the present invention.
[0058]
The power supply path 410 of the semiconductor integrated circuit 400 shown in FIG. 4 shares the power supply pad 411 between the digital circuit 420 and the analog circuit 430, and the ground path 440 of the semiconductor integrated circuit 400 connects the ground pad 441 to the digital circuit. This circuit is shared by the analog circuit 420 and the analog circuit 430. The circuit configuration of power supply path 410 in semiconductor integrated circuit 400 is the same as the circuit configuration of power supply path 210 in semiconductor integrated circuit 200 shown in FIG. 2, and the circuit configuration of ground path 440 in semiconductor integrated circuit 400. Is the same as the circuit configuration of the ground path 340 in the semiconductor integrated circuit 300 shown in FIG. Therefore, a detailed description of the semiconductor integrated circuit 400 is omitted, and the number of power supply and ground pads provided on the semiconductor integrated circuit 400 will be described.
[0059]
In the semiconductor integrated circuit 400 shown in FIG. 4, the power supply pad 411 is connected to the power supply pad 411 while suppressing the propagation of noise by using the inductor 412 disposed on the power supply path 410 and the inductor 442 disposed on the ground path 440. The digital circuit 420 and the analog circuit 430 are shared, and the ground pad 441 is shared by the digital circuit 420 and the analog circuit 430. As a result, in the semiconductor integrated circuit 100 shown in FIG. 1, four pads for power supply and four for the ground path are required, and six pads are required if the above-described separation region is counted as one pad. In the semiconductor integrated circuit 500 shown in FIG. 4, only two power supply circuits are required for the power supply and the ground path.
[0060]
【The invention's effect】
As described above, according to the semiconductor integrated circuit of the present invention, the number of power supply or ground pads can be reduced while suppressing the noise generated in the digital circuit from propagating to the analog circuit.
[Brief description of the drawings]
FIG. 1 is a diagram showing a semiconductor integrated circuit including an analog circuit power supply path and a digital circuit power supply path, and an analog circuit ground path and a digital circuit ground path.
FIG. 2 is a diagram showing one embodiment of a first semiconductor integrated circuit of the present invention.
FIG. 3 is a diagram showing one embodiment of a second semiconductor integrated circuit of the present invention.
FIG. 4 is a diagram showing one embodiment of a third semiconductor integrated circuit of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 100 semiconductor integrated circuit 101 substrate 110 power supply path 111 power supply pins 112, 113 bonding wire 114 digital circuit power supply path 114a digital circuit power supply pad 114b digital circuit power supply line 115 analog circuit power supply path 115a analog circuit power supply pad 115b Analog circuit power supply lines 116, 146 Isolation region 120 Digital circuit 130 Analog circuit 140 Ground path 141 Ground pin 142, 143 Bonding wire 144 Analog circuit ground path 144a Analog circuit ground pad 144b Analog circuit ground line 145 Digital circuit Ground path 145a Digital circuit ground pad 145b Digital circuit ground line 200 First semiconductor integrated circuit 20 of the present invention Substrate 210 Power supply path 211 Power supply pin 212 Bonding wire 213 Power supply pad 214 Power supply line 215 Inductor 220 Digital circuit 230 Analog circuit 240 Ground path 300 Second semiconductor integrated circuit 310 of the present invention Power supply path 320 Digital circuit 330 Analog circuit 340 Ground Path 341 ground pin 342 bonding wire 343 ground pad 344 ground line 345 inductor 400 third semiconductor integrated circuit 410 of the present invention power supply path 411 power supply pad 412, 442 inductor 420 digital circuit 430 analog circuit 440 ground path 441 ground pad W, Wa, Wd power

Claims (2)

An analog circuit that performs analog signal processing;
A digital circuit for performing digital signal processing;
A power supply pad shared by the analog circuit and the digital circuit;
An inductor disposed on a power supply path to the digital circuit;
A semiconductor device comprising: a power supply line for directly supplying power supplied from outside via the power supply pad to the analog circuit and supplying the digital circuit to the digital circuit via the inductor. Integrated circuit. An analog circuit that performs analog signal processing;
A digital circuit for performing digital signal processing;
A ground pad shared by the analog circuit and the digital circuit;
An inductor disposed on a ground path from the digital circuit to the ground pad;
A semiconductor integrated circuit, comprising: a ground line that directly connects the ground pad and the analog circuit and connects the ground pad and the digital circuit via the inductor.

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