JP3498090B2 - Semiconductor integrated circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit which has a high integration density and reduces the standby current consumption.

[0002]

2. Description of the Related Art A CMOS circuit is well known as a semiconductor integrated circuit that consumes very little power during standby. When the input is at the high level, the p-channel MOS transistor is off, the n-channel MOS transistor is on, and when the output capacitive load is completely discharged, the n-channel MOS transistor is turned off. In this state, the power consumption is ignored. it can. When the input is at the low level, the p-channel MOS transistor is on and the n-channel MOS transistor is off. When the output capacitive load is charged, the p-channel MOS transistor is turned off. Can be ignored. On the other hand, a miniaturized MOS transistor is used for the internal circuit in the chip, and an internal power supply voltage lower than the external power supply voltage is applied to the internal voltage drop circuit (ON A semiconductor integrated circuit with a high integration density, which is generated by a chip voltage limiter and supplies this internal power supply voltage to an internal circuit, has been disclosed in the prior art.
2761.

On the other hand, in Japanese Patent Laid-Open No. 63-140486, the rise speed of the transient current in the internal circuit immediately after the power is turned on is increased, while the peak value of the transient current is suppressed. Connect the current mirror circuit,
A method is disclosed in which the current supplied to the internal circuit is limited and the increase in the voltage supplied to the internal circuit is clamped to a predetermined value by feedback.

[0004]

However, the recent progress in fine processing technology used for semiconductor integrated circuits is remarkable, and the processing dimension is approaching 0.1 μm. Compared with a MOS transistor having a channel length of 1 μm, the MOS transistor having a channel length of about 0.1 μm has a lower threshold voltage and the drain current is 0 even if the gate-source voltage becomes less than the threshold voltage. I won't. The leak current in the region where the gate-source voltage is equal to or lower than the threshold voltage is called a subthreshold current and is exponentially proportional to the gate-source voltage. On the contrary, the threshold voltage is defined as a region in which the drain current is exponentially proportional to the gate-source voltage. For example, when the gate width is 10 μm, the drain current of 10 nA flows between the gate and the source. Voltage. This increase in subthreshold current caused by miniaturization has a problem that it is against the demand for lower power consumption of integrated circuits. In particular, the power consumption of a semiconductor integrated circuit using a miniaturized MOS transistor in a non-operating state is determined by this subthreshold current, and it is necessary to suppress this subthreshold current in order to achieve low power consumption. .

By forming a word driver for driving a word line of a semiconductor memory with a CMOS circuit, low power consumption of the semiconductor memory can be realized. However, if the MOS transistor of the CMOS circuit of the word driver is miniaturized, the following problems occur. That is,
Since the parasitic capacitance of the word line is large, M with a large gate width
It is necessary to use the OS transistor as the drive transistor of the word driver. Therefore, the total gate width of the word driver reaches about half of the total gate width of the entire DRAM chip. However, since the subthreshold current increases in proportion to the gate width, using a MOS transistor having a large gate width as a drive transistor of a word driver causes a problem that power consumption of the CMOS circuit of the word driver in standby becomes large.

That is, since a semiconductor memory generally uses a large number of word drivers, it is necessary to suppress the subthreshold current of the drive MOS transistor of the word driver composed of the CMOS circuit. For example,
Taking a 4 Mb DRAM as an example, the refresh period is 16 m.
A period of about 15.9 msec (actually 99% or more) in sec is a period in which all word lines are in the non-selected state, and in this non-selected state, the subthreshold current of the drive MOS transistor of the word driver flows. Therefore, the power consumption in the non-selected state is determined by the subthreshold current of the drive MOS transistor miniaturized by the word driver. Such a problem becomes a serious problem particularly in the case of a battery-operated semiconductor integrated circuit.

On the other hand, if the technique of the voltage drop circuit disclosed in Japanese Patent Laid-Open No. 57-172761 is applied to a semiconductor memory such as the above DRAM, the internal power supply voltage of an internal circuit including a MOS transistor having a large subthreshold current is Supplied from the output of the on-chip voltage limiter. However, in this case, the on-chip voltage limiter does not have the function of limiting the output current, so that the subthreshold current, which has been a problem, cannot be reduced.

On the other hand, if the technique of the current mirror circuit disclosed in Japanese Patent Laid-Open No. 63-140486 is applied to a semiconductor memory such as the above DRAM, the internal power supply voltage of an internal circuit including a MOS transistor having a large subthreshold current and The internal power supply current is supplied from the output transistor of the current mirror circuit. However, in this case, although the current mirror circuit has a current limiting function of limiting the peak value of the transient current of the internal circuit to a predetermined value or less, the subthreshold current corresponding to this predetermined value is smaller than the above-mentioned subthreshold current. It is a much larger value, and again, it is not possible to reduce the subthreshold current which has been a problem in the above.

Therefore, an object of the present invention is to refine C
It is an object of the present invention to provide a semiconductor integrated circuit in which standby power consumption is not determined by a large subthreshold current due to miniaturization even if a MOS circuit is used.

[0010]

In order to achieve such an object, a switching MOS transistor is provided with a plurality of CMOs.
It is provided between the first power supply terminal common to the S circuits and the external power supply terminal or the internal power supply terminal which is the output of the on-chip voltage limiter, and the gate of the switching MOS transistor is
A control signal with a voltage amplitude smaller than the absolute value of the threshold voltage is applied between the sources, and the first of the plurality of CMOS circuits is applied.
First subthreshold that flows from the external power supply terminal or the internal power supply terminal which is the output of the on-chip voltage limiter through the source-drain path of the switching MOS transistor when the power supply terminal of the switching MOS transistor and the second power supply terminal are short-circuited. A plurality of MOs having the same conductivity type channel as the switching MOS transistor whose source included in a plurality of CMOS circuits is electrically connected to the first power supply terminal
When a signal having a voltage amplitude smaller than the absolute value of the threshold voltage is applied between the gate and source of the S transistor and the source and drain of the switching MOS transistor are short-circuited, an external power supply terminal or an on-chip voltage Multiple CMOs from the internal power supply terminal which is the output of the limiter
The device parameter of the switching MOS transistor is set to be smaller than the second subthreshold current flowing through the source-drain path of the MOS transistor of the S circuit.

In the standby state, a plurality of CMOS in the off state
The circuit current is limited to the subthreshold current of the switching MOS transistor in the off state.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described with reference to Examples. Unless otherwise specified, a symbol representing a terminal name simultaneously serves as a wiring name and a signal name, and in the case of a power supply, also serves as a voltage value thereof.

FIG. 1 is a diagram showing a first embodiment of the present invention. Ci (i = 1 to n) is a logic circuit or driver configured by using CMOS transistors, but attention is focused on driving the output terminal Oi, and a simple CMOS inverter is taken as an example here. Ii is its input terminal. VS and V
C is a power supply line from an internal power supply generated by an external power supply or an internal voltage conversion circuit such as an internal voltage down converter or an internal voltage booster. The external power supply voltage is, for example, about 1.5 to 3.6V. VC is set to, for example, 1.5 to 2.5V. V
S is normally 0V. The switch circuit S1 is inserted between this Ci and VC. T1 is a control terminal of this switch circuit. For the switch circuit S1, for example, a MOS transistor or a bipolar transistor is used. N1 is C
It is the first power supply terminal of the MOS inverter group. N2 is C
It is the second power supply terminal of the MOS inverter group.

The operation of this circuit will be described with reference to FIG.
Here, consider a case where only one circuit (here, C1) operates during operation. In other words, the current supplied by the switch S1 during operation may be only one circuit of Ci (current consumption in C1 here). Further, in FIG. 2, T1
Is high when S1 is on and when T1 is low
1 is set to turn off.

During the first standby, all the inputs Ii of Ci are high level VC and the outputs Oi are all low level VS. At this time, the p-channel MOS transistor is normally off and the n-channel MOS transistor is normally on. However, due to miniaturization, the off-state subthreshold current becomes a problem. That is, the subthreshold current which becomes a problem when the switch S1 is not provided is a current flowing from VC to VS through the p-channel MOS transistor which is off and the n-channel MOS transistor which is on when the output Oi is at a low level. . In this embodiment, T1 is set to a low level during standby, and the switch S1 is turned off. However, even if the switch S1 is turned off, the leak current of the switch S1 cannot be ignored. However, the leak current of the switch S1 is set smaller than the above-mentioned subthreshold current. Therefore, at this time, the maximum current from VC to Ci is the leak current of the switch S1. As a result, even if a MOS transistor having a low threshold voltage is used for Ci for low voltage operation, the current flowing in Ci is determined not by the subthreshold current but by the leak current of the small switch S1. It Therefore, the current consumption during standby is also small.

Next, at the time of operation, T1 becomes high level, S1 is turned on, and S1 is in a state of supplying the current necessary for charging the output O1 of C1. Here, the input I1 changes to the low level VS, and the output O1 rises to the voltage VC by the current from the power source VC. After that, the force I1 becomes high level VC and the output O1 becomes low level VS. When the above operation is completed, T1 becomes low level again in the standby state, and S1 is turned off.

The switch S1 is a p-channel MOS.
It can be formed of a transistor or a pnp bipolar transistor.

FIG. 3 is a diagram showing a second embodiment of the present invention. The difference from FIG. 1 is that the switch S is connected between VC and Ci.
Instead of providing 1, switch S2 between VS and Ci
, The first power supply terminal N1 and the second power supply terminal N
2 is the opposite. Others are the same as those in FIG.
The operation of this circuit is shown in FIG.

In the circuit of FIG. 3, the leak current of the switch S2 is set to be smaller than the subthreshold current of the n-channel MOS transistor of the circuit Ci in which the low potential is applied to the input Ii. Therefore, at this time, from Ci to V
The maximum current to S is the leakage current of switch S2. As a result, even if a MOS transistor having a low threshold voltage is used for Ci for low voltage operation, the current flowing in Ci is not determined by the subthreshold current but by the leak current of the small switch S2. It Therefore, the current consumption during standby is also small.

The switch S2 is an n-channel MOS.
It can be formed of a transistor or an npn bipolar transistor.

FIG. 5 is a diagram showing a third embodiment of the present invention. In this embodiment, the switch S of the first embodiment shown in FIG.
1 is specifically composed of a p-channel MOS transistor. The current drive capability of the p-channel MOS transistor S1 is set in consideration of the number of circuits Ci that charge the output Oi in response to the low potential input Ii. On the other hand, in order to reduce the standby current consumption, it is necessary to reduce the leak current of the switch S1 to a small value as described above.
Therefore, it is necessary to set the device parameter of the p-channel MOS transistor of the switch S1. For example, the gate width of the p-channel MOS transistor of the switch S1 is the same as the p-channel MOS transistors of the circuits C1, C2 ...
It is set smaller than the total gate width of the transistors and larger than the gate width of the p-channel MOS transistors of one circuit Ci. In order to reduce the leak current, it is possible to increase the threshold voltage of the p-channel MOS transistor of the switch S1, increase the gate length, or increase the gate insulating film thickness. This makes it possible to reduce the current consumption during standby.

The operation of this circuit will be described with reference to FIG.
It should be noted that only one circuit C1 outputs a high potential during operation.

First, in the first standby mode, all the inputs Ii of Ci are at the high level VC and all the outputs Oi are at the low potential VS, as in the previous embodiment. Also, C1, C2 ...
Since the subthreshold current flowing through the switch element S1 is smaller than the sum of the subthreshold currents of Cn,
The potential of the common power supply terminal N gradually decreases. Then, for example, considering a p-channel MOS transistor of the circuit C1, its gate voltage is VC, but its source voltage is VC.
Will be lower. That is, since the p-channel MOS transistor is turned off even more strongly, the subthreshold current is greatly reduced. The gate-source voltage dependence of the subthreshold current is approximately DECADE / 100
It is about mV. Therefore, the subthreshold current becomes 1/100 if the voltage drops by 0.2V.
Therefore, if the standby period becomes long to some extent, the potential consumption of the terminal N decreases, and the current consumption can be reduced to a negligible level.

During operation, the p-channel MOS transistor S
Since T1 is turned on, the difference from the previous embodiment is that T1 becomes the low level VS, and the other points are the same as in the previous embodiment. The switch S1 can also be formed by a pnp bipolar transistor.

In the case of a bipolar transistor, at least one power supply terminal of a plurality of CMOS circuits having first and second power supply terminals and an external power supply terminal or an internal power supply terminal which is an output of an on-chip voltage limiter. An npn or pnp switching bipolar transistor is provided between the two. The first of the plurality of CMOS circuits
And the leakage current when the switching bipolar transistor is off when the second power supply terminal is shorted, and the subthreshold current when multiple CMOS circuits are off when the switching bipolar transistor is shorted (not shorted). The device parameters of the switching bipolar transistor are set so that The device parameter is, for example, the emitter width.

FIG. 7 is a diagram showing a fourth embodiment of the present invention. In this embodiment, the potential of the first power supply terminal N1 is maintained in parallel with the switch S1 of the third embodiment shown in FIG. 5 between the power supplies VC and Ci at a predetermined potential between VC and VS. It is characterized by having a voltage clamp circuit L.

For example, in the voltage clamp circuit L, the drain is set to VC, the gate is set to a predetermined potential, and the source is connected to the terminal N1. The source follower operation n-channel MOS transistor is formed. It In this embodiment, this voltage clamp circuit is realized by a diode-connected n-channel MOS transistor whose gate and drain are short-circuited.

The features and operation of this circuit will be described with reference to FIG. The initial state is the same as the case described with reference to FIGS. At this time, the potential of the common power supply terminal N1 of Ci is as shown in FIG.
When there is a voltage clamp circuit L as shown in (solid line)
If it does not exist (broken line), it differs during standby. If an extremely long standby time continues, the potential of the terminal N1 drops to VS in the worst case due to the subthreshold current flowing in Ci and other leakage current when there is no voltage clamp circuit L. Therefore, in order to shift from the standby state to the operating state, the common power supply terminal N1 must be charged first, so that there is a delay in shifting to the operating state until the charging is completed. On the other hand, if the threshold voltage of the n-channel MOS transistor forming the voltage clamp circuit L is VT,
When there is the voltage clamp circuit L, the potential of the common power supply terminal N drops only to VC-VT. Therefore, the transition to the operating state is completed in a short time. It should be noted that N1 is set so that the subthreshold current of Ci in the standby state when VC is applied to the input becomes small enough to be ignored as in the previous embodiment.
The level of the clamp potential VC-VT is set.
For example, when VT is 0.2 V, the gate-source voltage dependence of the subthreshold current is DECADE / 100.
If it is mV, the subthreshold current can be reduced to 1/100 or less.

According to the present invention, an operation mode in which a semiconductor integrated circuit including a large number of CMOS circuits of the same type is in a standby state (a state in which it is not possible to guarantee that valid data is output from the output when the power supply voltage is not substantially supplied) Is suitable for reducing the current consumption in the standby state.

Semiconductor memory, for example, dynamic random access memory (DRAM), static random access memory (SRAM), or EEPRO
A non-volatile memory such as M has a word decoder, a word driver, a Y system decoder, and a Y system driver. Therefore, in the standby state of the semiconductor memory in which it cannot be guaranteed that valid data is output, the battery operation can be guaranteed for a long time by greatly reducing the current consumption of such a decoder or driver.

By applying the CMOS circuit of the present invention to such a decoder or driver, current consumption can be greatly reduced and long-time battery operation can be guaranteed.

FIG. 9 is a diagram showing an example in which the present invention is applied to a word driver / decoder of a dynamic random access memory. WD1 to WD8 are word drivers and correspond to Ci in FIG. 1, and a switch for supplying current from the power supply VCH to this is S11. XD1 is a decoder, which also corresponds to Ci in FIG.
A switch for supplying a current from L is S12. The power supply voltage VCH for the word drivers WD1 to WD8 is set to a high voltage necessary to take a sufficient storage voltage of a memory cell (not shown). For example, if the storage voltage of the memory cell is 1.5V, VCH is set to 2.5V. Since the power supply voltage VCL for the decoder XD1 does not need to directly drive the memory cell, it is set to a voltage as low as possible so that current consumption is reduced and speed is not deteriorated so much. For example, it is set to 1.5V. Therefore, VCH is set higher than VCL. VCH can also be obtained, for example, by boosting the external power supply voltage. The circuit block XB1 is configured by WD1 to WD8 and XD1, and there are n such circuit blocks XB1 to XBn. W11
Wn8 is a word line. In WD1, the pMOS MW1 and the nMOS MW2 are CMOS inverters that drive the word line W11. XDPH is a precharge signal. The basic operation of this WD1 is disclosed in JP-A-6
2-178013, when the nMOS MS1 is off, the XMPH turns on the PMOSMP1 to turn on the terminal N.
3 is precharged to VCH and W11 which is the output of the CMOS inverter is set to the low level VS.
The SMS1 is selectively turned on to lower the potential of N3 to invert the CMOS inverter.
The pMOS MF1 applies a weak feedback from the output to the input of the CMOS inverter to prevent malfunction. MS1
Is controlled by Xm and the output N2 of the decoder described later. Conventionally, in such a word driver, pMOS
The MW1 was directly connected to the power supply VCH along with other word drivers. In general, the MW1 has a large load on the word line, and therefore the one having a large gate width is used. For this reason, the total gate width of a large number of word drivers occupies most of the total gate width of the logic circuits of the entire chip.
Conventionally, the MOS for such a large gate width is the power supply VC.
It was connected to H. For this reason, if the power supply voltage is lowered in accordance with the decrease in the source-drain breakdown voltage of the MOS due to the miniaturization of processing technology, and the threshold voltage is lowered in order to maintain high-speed operation under this power supply voltage, the subthreshold current Had the problem of increasing. This increases the standby current, and even if the battery can be driven by lowering the voltage, it becomes an obstacle in terms of current consumption. In the present invention, the switch S11 is provided between the power supply VCH of the word driver and many word drivers. Many word drivers are connected to the output VCHL of the switch S11. This switch S11 is composed of pMOS, and this pM
The gate width of the OS can be small because it is sufficient that current can be supplied to the word drivers operating at one time. This p
Since the MOS is connected to VCH, the subthreshold current can be small. This solves the conventional problems. For example, the gate width of MW1 is 20μ
If m is set and one S11 is provided for every 512 word drivers, pM controlled by T11 in this S11
The gate width of the OS may be 200 μm. Further, the threshold voltage of this pMOS is set to be higher than MW1 in absolute value, for example, by 0.1V. This makes it possible to reduce the subthreshold current by three digits.

The configuration of the decoder XD1 is similar. The only difference from the word driver is that nMOS MS21 and MS22 in two stages are arranged in place of MS1 of the word driver. MD1 and MD2 are CMOS inverters that drive the output terminal N2 of the decoder, and MP2
Is a PMOS for precharge, XDP is a precharge signal, and MF2 is a pMOS that provides weak feedback from the output of the CMOS inverter to the input. MS2
1 and MS22 are controlled by Xi, Xj, and Xk. Even in such a decoder, MD1 is conventionally directly connected to the power supply VCL. For this reason, a large number of decoder MOSs are connected to VCL, and if the processing technology becomes finer and the threshold voltage is made smaller as the power supply voltage drops, a large subthreshold current will flow. According to the present invention, a switch S12 is provided between the power supply and a large number of decoders, and this output VCLL is connected to the decoders. In this case, the gate width of the pMOS forming this switch can be made small as long as the current can be supplied to a small number of operating decoders. Since this pMOS is connected to VCL, the subthreshold current can be reduced.

Next, the operation of this circuit will be described with reference to FIG. Although not shown in FIG. 9, / RAS is a signal which is applied to the chip and controls whether or not to operate this word driver / decoder group. From this signal and a so-called address signal that also specifies which word line to be applied from the outside of the chip, a signal necessary for operating the circuit of FIG. 9 by a circuit in the chip not shown in FIG. 9 is generated. To do. Initially, / RAS is high and the chip is in a standby state. At this time, Xi is high level V
CL and Xj and Xk are low level VS, so M
S21 and MS22 are turned off and the decoder is in a non-selected state. Furthermore, since XDP is low level VS, pMO
SMP2 is turned on and the input N1 of the CMOS inverter of the decoder is precharged to VCL, so that the output N2 of the decoder is at the low level VS. On the other hand, in the word driver, Xm is high level VCL, and N2
Is the low level VS as described above, the nMOS MS1
Is off. Since XDPH is at the low level VS, pMOS MP1 is turned on and N3 is precharged to the high level VCH, so that the word line W11 is at the low level. The same applies to the other word drivers / decoders, and all word lines are at the low level VS. Next, in the operating state, / RAS becomes low level, and the precharge signal XDP becomes high level VCL, XDP.
H becomes the high level VCH. T11 and T12 also become low level VS, and the switches S11 and S12 are turned on.
Further, Xi and Xm become low level VS, and Xj and Xm
k becomes the high level VCL. As a result, M21 and M22 are turned on, so that N1 is discharged toward Xi to the low level VS. For this reason, N2 is at the high level VCL and Xm is at the low level VS, so that MS1 is turned on, and N3 is discharged toward Xi to the low level VS. As a result, W11 becomes high level, and the memory cell connected to this is selected. After this, when / RAS changes to the high level again, Xi, X
Since j, Xk, and Xm return to the standby state, and XDP and XDPH also return to the initial state, the word driver / decoder is in the non-selected state and precharged for the next operation. Although FIG. 9 shows the case of the word driver / decoder, this can also be applied to the Y driver / decoder. In this case, since it is not necessary to directly drive the memory cell, VCH in FIG.
The potential may be the same as L.

FIG. 11 shows the switches S11 and S1 of FIG.
An example of the second control circuit will be shown. MA is the input signal of this control circuit. In FIG. 11, T11 is provided for S11 and T12 is provided for S12, but this control circuit controls S11 and S12 by one output signal T. The operation of this circuit will be described with reference to FIG. In the non-selected state where / RAS is at the high level, MA is at the low level VS, so the nMOS MG2 is off. Also, CM
Due to the OS inverter, M1 is at high level VCL.
Therefore, in the level conversion circuit which constitutes the flip-flop and whose power source is connected to VCH, M2 is set to the low level VS.
And the pMOS MG1 is on. Therefore, T is a high level VCH, and the switch S11
And S12 are off. Next, / RAS becomes high level, and when it is in operation, MA becomes high level VCL,
M1 becomes low level VS. As a result, the NOR flip-flop is inverted and M2 becomes the high level VCH. Here, since MA is input to the gate of the nMOSMG2, when the MA becomes a high level, the nMOSMG
2 turns on. Although the pMOSMG1 is turned off with a delay because M2 becomes high level by the above-described operation, by setting the gate width of MG2 sufficiently larger than MG1, T changes to low level by changing MA to high level VCL. It can be VS. Since it is necessary for high-speed operation to turn on the switches S11 and S12 as soon as it is in operation, it is advisable to adopt such a circuit configuration. When / RAS goes high and returns to the non-selected state, MA goes low first and MG
Turn off 2. Then the flip-flop operates and MG
1 is turned on and T is set to a high level. As a result, the switches S11 and S12 are turned off.

FIG. 13 is a diagram showing the configuration of a data processing system using the semiconductor memory of the present invention for the memory device M.
Arrows indicate the flow of signals. M is DRA using the present invention
M, CPU is a processing unit that controls the entire system,
AG is a refresh address generator, TC is a control signal generator, SLCT is a select device for switching an address signal sent from a CPU and a refresh address signal sent from RAG, and PFY is another device in the system. (For example, an external storage device, a display device, a numerical operation device, etc.) are shown. The PFY may be connected to another information processing device through a communication line.

DATA is data communicated between the CPU and M, Aic is an address signal generated by the CPU,
Air is a refresh address signal generated by RAG, Ai is an address signal selected by SLCT and sent to M, ST is a status signal sent from CPU to RAG, BS is a busy signal from TC to CPU, and SE is Signal sent from TC to activate SLCT, / R
AS and / CAS are signals for activating the DRAM using the present invention. SG collectively represents the exchange of signals between the CPU and other devices in the system. M
An SRAM, an EEPROM or the like is also conceivable. At this time, of course, there are corresponding start signals and control signals.

In the embodiment of FIG. 13, / RAS signal and / C
The AS signal is set to the high level, and the memory device M of the DRAM is
Shifts to the standby state of ultra-low current consumption as described in the previous embodiment. At this time, the CPU can also enter the low power consumption standby state and the other peripheral devices can also enter the low power consumption standby state by the sleep command.

In the semiconductor integrated circuit using the present invention, the consumption current can be made smaller than the subthreshold current of the MOS transistor having a small threshold voltage under a low power supply voltage suitable for battery driving. Therefore, it is possible to realize a semiconductor integrated circuit that operates at high speed, has a low voltage, and has a small standby current.

[0040]

The current flowing through the plurality of CMOS circuits during standby is set not by the subthreshold currents of the plurality of CMOS circuits but by a small leak current of the switch transistor. Thus, even if the CMOS circuit is miniaturized and the subthreshold current becomes large, the standby current consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment.

FIG. 2 is a diagram showing an operation of the first embodiment.

FIG. 3 is a diagram showing a second embodiment.

FIG. 4 is a diagram showing an operation of the second embodiment.

FIG. 5 is a diagram showing a third embodiment.

FIG. 6 is a diagram showing an operation of the third embodiment.

FIG. 7 is a diagram showing a fourth embodiment.

FIG. 8 is a diagram showing an operation of the fourth embodiment.

FIG. 9 is a diagram showing an application of the present invention to a word driver / decoder.

10 is a diagram showing the operation of the circuit of FIG. 9. FIG.

FIG. 11 is a diagram showing an example of a control circuit.

12 is a diagram showing an operation of the circuit of FIG. 11. FIG.

FIG. 13 is a diagram showing a system configuration using the present invention.

[Explanation of symbols]

S, S1, S2, S11, S12 ... Switch, T, T
1, T2, T11, T12 ... Switch control terminal, Ci ...
Numerous circuits that operate only a small number at a time, N1, N2 ... Power supply terminals, VC ... High potential side power supply, VS ... Low potential side power supply, I
Input, O ... Output, VCH ... High potential side power source of word driver, VCL ... High potential side power source of decoder, WD1 to WD
8 ... Word driver, XD1 ... Decoder, XB1 to XB
n ... Word driver / decoder, W11 to Wn8 ... Word line, Xi, Xj, Xk, Xl ... Word driver / decoder selection signal, MA ... Control circuit input signal, M ... Memory,
DRAM, CPU ... System control processor, SLT ... Address select device, RAG ... Refresh address generator, TC ... Control signal generator, PFY ... Other devices in system, DATA ... Data signal, Aic, Air,
Ai ... Address signal, ST ... Status signal, BS ... Busy signal, SE ... Start signal, / RAS, / CAS ... DR
AM activation signal.

Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI H01L 27/10 481 H01L 27/10 681F 27/108 H03K 19/00 (72) Inventor Takesada 3681 Hayano, Mobara-shi, Chiba Hitachi Devices Engineering Co., Ltd. (72) Inventor Masashi Horiguchi 1-280, Higashi Koikekubo, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Inventor Takao Watanabe 1-280, Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Center, Hitachi Ltd. (72) Inventor Goro Tachibagawa 1-280, Higashi Koigokubo, Kokubunji, Tokyo Inside Hitachi Central Research Laboratory (72) Inventor Yasushi Kawase 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Tachibana Riichi 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Masakazu Aoki 1-280, Higashi-Kengokubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central In-house (56) References JP-A-60-48525 (JP, A) JP-A-61-150365 (JP, A) JP-A-56-56666 (JP, A) (58) Fields investigated (Int.Cl . ^7, DB name) H01L 21/822 H01L 21/8238 H01L 21/8242 H01L 27/04 H01L 27/092 H01L 27/10 H01L 27/108 H03K 19/00

Claims (14)

(57) [Claims] 1. A source between a first potential point and a second potential point
A source-drain path is provided between an electronic circuit including a first conductivity type first MOS transistor having a drain path and a source connected to the first potential point, and a third potential point and the first potential point. a, the source is connected to the third potential point 1
A second MOS transistor of a conductive type, and by applying a control signal to the gate of the second MOS transistor to set the control signal to the first state, the second MO transistor is formed.
With the S transistor turned on, a current is allowed to flow between the first potential point and the second potential point via the source / drain path of the first MOS transistor in the on state, and the control signal By setting the second state, the second MO
When the S transistor is turned off, a subthreshold current flowing between the first potential point and the second potential point via the source / drain path of the first MOS transistor in the off state is applied to the second MOS transistor in the off state. A semiconductor integrated circuit, which is limited by a characteristic, wherein an operating voltage determined by the third potential point and the second potential point is supplied from an internal step-down circuit. 2. The semiconductor integrated circuit according to claim 1, further comprising a voltage clamp circuit connected in parallel with the second MOS transistor. 3. The electronic circuit according to claim 1 or 2, wherein the electronic circuit is a CMOS circuit,
Second conductivity type third MOS connected in series to the transistor
Including semiconductor integrated circuit the transistor. 4. The semiconductor according to claim 1, wherein the second MOS transistor has a threshold voltage whose absolute value is higher than that of the first MOS transistor. Integrated circuit. 5. The electronic circuit according to any one of claims 1 to 4, wherein the electronic circuit has a source / drain path between the first potential point and the second potential point, and the source is the first potential point. A semiconductor integrated circuit having a plurality of the first MOS transistors connected to a potential point. 6. The semiconductor integrated circuit according to claim 5, wherein a gate width of the second MOS transistor is narrower than a sum of gate widths of the plurality of first MOS transistors. 7. The semiconductor integrated circuit according to claim 1, wherein a gate oxide film thickness of the second MOS transistor is larger than a gate oxide film thickness of the first MOS transistor. 8. The semiconductor integrated device according to claim 1, wherein the subthreshold current flows due to a processing dimension of the first MOS transistor being in a region of 0.1 μm. circuit. 9. A first conductivity type first MOS transistor, and one or more MOS circuits, wherein the one or more MOS circuits are commonly connected to a first power supply terminal and a second power supply is provided. A gate of the first conductivity type first MOS transistor is commonly connected to a terminal, is controlled by a control signal, and a source of the first conductivity type first MOS transistor is electrically connected to a first operating potential; The drain of the first MOS transistor of the first conductivity type is electrically connected to the first power supply terminal, the second power supply terminal is electrically connected to a second operating potential, and the one or more MOS circuits are provided. Each include a second MOS transistor of the first conductivity type whose source is electrically connected to the first power supply terminal, and the first MOS transistor is the one or more MOS transistors.
When a signal having a voltage smaller than the absolute value of the threshold voltage is applied between the gate and the source of the second MOS transistor included in each of the circuits, the one or more MOSs are changed from the first operating potential. Source of the second MOS transistor of the first conductivity type included in each of the circuits
A subthreshold current flowing through the drain path to the second operating potential is limited to a value of a predetermined subthreshold current, and the predetermined subthreshold current is the first conductivity type first MOS transistor. When the control signal having a voltage smaller than the absolute value of the threshold voltage of the first MOS transistor of the first conductivity type is applied between the gate and the source, the first conductivity type of the first conductivity type is changed from the first operating potential. First MO
An operating voltage, which is a subthreshold current flowing through the source-drain path of the S transistor to the first power supply terminal and is determined by the first operating potential and the second operating potential, is supplied from an internal step-down circuit. Semiconductor integrated circuit. 10. The semiconductor integrated circuit according to claim 9, further comprising a voltage clamp circuit connected in parallel with the first MOS transistor. 11. The voltage smaller than the absolute value of the threshold voltage of the first conductivity type first MOS transistor between the gate and the source of the first conductivity type first MOS transistor according to claim 9 or 10. When the first power supply terminal and the second power supply terminal commonly connected to the one or more MOS circuits are short-circuited, The subthreshold current flowing to the second operating potential through the source-drain path of the first conductivity type first MOS transistor is referred to as a first subthreshold current, and the subthreshold current is included in each of the one or more MOS circuits. A signal having a voltage smaller than the absolute value of the threshold voltage is applied between the gate and the source of the first conductivity type second MOS transistor, and the first conductivity type is used. The source of the 1MOS transistor - when the drain is short-circuited, the first
From the operating potential to the second operating potential through the source-drain path of the second MOS transistor of the first conductivity type included in each of the one or more MOS circuits to the second subthreshold. And a device parameter of the first conductivity type first MOS transistor is set so that the first subthreshold current is smaller than the second subthreshold current. 12. The semiconductor integrated circuit according to claim 9, wherein the MOS circuit is a CMOS circuit. 13. The semiconductor integrated circuit according to claim 9, wherein a gate oxide film thickness of the first MOS transistor is larger than a gate oxide film thickness of the second MOS transistor. 14. The absolute value of the threshold voltage between the gate and the source of the second MOS transistor included in each of the one or more MOS circuits, which is smaller than the absolute value of the threshold voltage. When a voltage signal is applied, the second operating potential is passed from the first operating potential through the source-drain path of the second MOS transistor of the first conductivity type included in each of the one or more MOS circuits. The subthreshold current flowing to the operating potential is
A semiconductor integrated circuit characterized in that it flows due to a processing dimension of a MOS transistor being in a region of 0.1 μm.