JP2005259222A - Power supply voltage generation circuit and semiconductor device including power supply voltage generation circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply voltage generation circuit which can supply an external circuit with a stable power supply voltage, and also provide a semiconductor device which includes the power supply voltage generation circuit. <P>SOLUTION: The power supply voltage generation circuit 20 adjusts an external source voltage V<SB>CC</SB>, which is inputted from an external power source, to a prescribed voltage via a driver circuit, outputs it as an inner source voltage V<SB>DD</SB>to an external circuit, and is provided with a voltage control means which controls the inner power supply voltage by changing a first capacity connected to the external power supply side and a second capacity connected to the inner power supply side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power supply voltage generation circuit for generating an internal power supply voltage and a semiconductor device including the power supply voltage generation circuit.

  In a semiconductor device such as a nonvolatile memory, a circuit system that distinguishes between a memory cell, a memory peripheral circuit, an interface circuit, and the like corresponding to the progress of miniaturization and supplies an external power supply voltage and an internal power supply voltage to each system Has come to adopt. In such a circuit system, for example, a power supply voltage generation circuit for supplying an internal power supply voltage with reference to an external power supply voltage is mounted.

For example, FIG. 13 shows an example of a conventional power supply voltage generation circuit installed in a memory. Power supply voltage generating circuit 90 comparison circuit 91, the reference potential generation circuit 92 and the P-channel insulated gate field effect transistor driver circuit 93 consisting of (PMOS), the external power supply voltage _{V CC} is the voltage drop, to the internal power supply voltage _{V DD} Convert. The comparison circuit 91 compares the reference voltage V _ref input from the reference potential generation circuit 92 with the monitor voltage V _mon of the internal power supply voltage V _{DD divided} by the resistors R _a1 and R _a2 , and gates the gate of the PMOS 2 A voltage _Vout is applied.

The internal power supply voltage is output as an output voltage V _OP to a memory cell and a peripheral circuit (not shown) which are internal circuits. However, the internal circuit is affected by its operation status. That is, when the peripheral circuit starts operation, the current I _DD increases rapidly as shown in FIG. 14, and the comparison circuit 91 detects the decrease in the internal power supply voltage V _DD1 at the operation start time t ₁ . The output gate voltage _Vout operates to raise the internal power supply voltage _VDD1 . When the operation ends, the internal power supply voltage V _DD decreases again due to the capacitance C _DD . This movement occurs in a short time and causes a vibration phenomenon. When the capacity C _DD is insufficient, the internal power supply voltage oscillates more greatly as shown in the behavior of V _DD2 , for example. It is _{preferable that} the decrease in internal power supply voltage V _DDmin is small and the cycle Tφ is narrow.

  For example, in the case of a flash memory, the current consumption is large and the memory circuit operation is required to have high speed. Therefore, charging and discharging are repeated, and the oscillation of the internal power supply voltage as shown in FIG. Also, even in the operating state, the current consumption fluctuates sharply due to changes in the operating state of the internal circuit of the flash memory due to input commands such as program, verify, and erase so that the operating mode changes from read to write. Then, the vibration of the internal power supply voltage is further increased.

  Therefore, in order to suppress the oscillation of the internal power supply voltage as much as possible, for example, a region such as a peripheral circuit of the memory cell is used, and a large-capacity capacitive element capable of stably supplying a current is provided at the output node of the power supply voltage generation circuit. (For example, refer to Patent Document 1).

However, it is difficult to quantitatively estimate the capacitance of the capacitor that stabilizes the circuit operation by suppressing the oscillation of the internal power supply voltage, and the problem that the area for forming the capacitor cannot be sufficiently secured as the semiconductor device is miniaturized. was there.
JP 2002-334777 A (page 13, FIG. 7)

  The present invention has been made to solve the above problems, and provides a power supply voltage generation circuit capable of supplying a stable power supply voltage to an external circuit and a semiconductor device having the power supply voltage generation circuit. Objective.

  In order to solve the above-described problem, a first aspect of the present invention is a power supply that adjusts an external power supply voltage input from an external power supply to a predetermined voltage via a driver circuit and outputs the voltage to the external circuit as an internal power supply voltage. Voltage control means for controlling the internal power supply voltage by varying a capacity connected to the external power supply side and a capacity connected to the internal power supply side during operation of the external circuit. It is characterized by having.

  According to a second aspect of the present invention, as a semiconductor device, an external power supply voltage input from an external power supply is adjusted to a predetermined voltage via a driver circuit, and is output to an internal circuit as an internal power supply voltage. A power supply voltage generating circuit including voltage control means for controlling the internal power supply voltage by changing a capacity connected to the external power supply side and a capacity connected to the internal power supply side during operation of an internal circuit; It is characterized by that.

  According to the present invention, in order to detect the internal power supply voltage and feed back it to adjust the capacity, the power supply voltage generating circuit for supplying a stable power supply voltage following the charge / discharge in the circuit and the same are provided. A semiconductor memory device can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a circuit block diagram showing a semiconductor device according to a first embodiment of the present invention. The semiconductor device in this embodiment is, for example, a flash memory 10.

The flash memory 10 mainly includes a memory cell and a peripheral circuit 11 and includes interface circuits 12 and 13 on an input side (V _in ) and an output side (V _out ), respectively. First, the power supply voltage is supplied as the external power supply voltage _Vcc , and is adjusted to the internal power supply voltage V _DD in the internal power supply voltage generation circuit 14. The internal power supply voltage V _DD is supplied to, for example, the interface circuit 13 in the flash memory 10.

FIG. 2 shows a circuit block diagram of the power supply voltage generation circuit in this embodiment. The power supply voltage generation circuit 20 receives the external power supply voltage _Vcc from the external power supply, and drops the voltage by the driver circuit 23 made of PMOS, so that the internal power supply voltage V _DD is outside the power supply voltage generation circuit 20 from the drain side of the PMOS. , A voltage drop circuit that supplies V _op to other circuits in the flash memory.

In the power supply voltage generation circuit 20, the gate voltage _Vout of the driver circuit 23 is controlled by the comparison circuit 21. That is, the reference voltage _{V ref} sent from the reference voltage generator circuit 22, resistor _{R 21} and the resistor compares the monitor voltage _{V mon} of the divided internal power supply voltage _{V DD} by _{R 22,} the monitor voltage _{V mon} reference voltage When the level becomes lower than V _ref , the comparison circuit 21 selects the reference voltage V _ref and adjusts the gate voltage V _out so as to increase the current flowing through the driver circuit 23. On the other hand, when the monitor voltage V _mon becomes higher than the reference voltage V _ref , the comparison circuit 21 selects the monitor voltage V _mon and adjusts the gate voltage V _out so as to reduce the current flowing through the driver circuit 23.

Capacitance elements C _DD , C _CC , and C _CD are formed in the power supply voltage generation circuit 20 in order to perform stable circuit operation. The supply line for the external power supply voltage _Vcc has a first capacitive element C _CC , the supply line for the internal power supply voltage V _DD has a second capacitive element C _DD , and the switch circuit 24 has a third capacitive element C _CD. Each is connected.

The connection of the switch circuit 24 can be switched to the external power supply side or the internal power supply side. Thus, changing the connection of the third capacitor _{C CD.} That is, the circuit operates in the flash memory to be connected to the power supply voltage generating circuit 20, when the current I _DD flows to the supply line of the internal power supply voltage V _DD, the third capacitor C _CD by switching the switch circuits 24 The first capacitor connected to the supply line of the internal power supply voltage V _DD and connected to the external power supply voltage side is reduced to only the first capacitor element _CC . On the other hand, by adding the third capacitor element _CD to the first capacitor element _CC , the second capacitor connected to the internal power supply voltage side is increased. The internal power supply voltage V _DD is stabilized by feeding back the capacitance in this way.

The switch circuit 24 includes, for example, a switch switching unit and a control unit. FIG. 3 shows an example of the switch switching unit 30. The switch switching unit 30 is composed of four MOS transistors and is basically symmetrical with respect to the internal power supply voltage V _DD and the external power supply voltage _Vcc . For example, voltages V _a1 and −V _a1 each having a value opposite in phase turn on the PMOS 20 and NMOS 20 respectively, while voltages V _a2 and −V _a2 each having a value opposite in phase turn off the PMOS 21 and NMOS 21, respectively. . Accordingly, the third capacitor _{C CD,} for example, switching from the external power supply voltage _{V cc} to the internal power supply voltage _{V DD.}

FIG. 4 shows a control unit 40 of the switch circuit that operates the MOS transistor of the switch switching unit 30. In the two comparison circuits 41a and 41b, the control unit 40 uses the reference voltage V _ref sent from the reference power supply generation circuits 42a and 42b and the monitor voltage of V _DD divided by the resistors R ₄₁ and R ₄₂ . Compare and select either. The comparison circuit 41a outputs voltages V _a1 and −V _a1 whose values are opposite phases, and the comparison circuit 41b outputs the voltages V _a2 and −V _a2 whose values are opposite phases, respectively, via inverters. .

In this control unit 40, if the potential of the internal power supply voltage _{V DD} is decreased, the output _{V OA} of the comparison circuit 41a becomes a low level. The inverters control the voltages to the opposite phase voltages V _a1 and −V _a1 , respectively. The same applies to the voltages V _a2 and −V _a2 .

FIG. 5 shows an example of a signal waveform that shows temporal changes in current and voltage in the power supply voltage generation circuit when an external circuit of the power supply voltage generation circuit operates. By turning on the external power supply, a stable current and voltage are displayed in a state where _VCC is supplied. At time t _1, the flash memory 10 shown in FIG. 1 is operational, the current I _DD flowing through the power supply voltage generating circuit 20 shown in FIG. 2 rises sharply. As a result, the internal power supply voltage V _DD decreases, and the monitor voltage V _mon decreases _relative to the reference voltage V _ref . As a result, the output voltage _Vout of the comparison circuit decreases.

At this time, it operates the switch circuit 24 shown in FIG. 2, switches the capacitor C _CD to reduce the voltage drop of the internal power supply voltage V _DD to connect to the internal power supply voltage side V _DD. If a result, the voltage of the internal power supply voltage _{V DD} rises, the reference voltage _{V ref,} the monitor voltage _{V mon,} occur a phenomenon opposite to the output voltage _{V out} of _the comparator circuit, to connect the capacitor _{C CD} to the external power supply voltage side _{V CC} Thus, the switch circuit 24 performs switching. This is the basic circuit operation.

By such a feedback operation, it is possible to reduce the vibration of the internal power supply voltage V _DD and the external power supply voltage _VCC as shown in FIG. Therefore, it is possible to provide a power supply voltage generation circuit with stable operation. Furthermore, as shown here, a semiconductor device such as a flash memory with good performance can be obtained by incorporating a power supply voltage generating circuit with stable operation into a semiconductor device such as a flash memory.

  Further, by switching and utilizing the capacitive element, it is possible to reduce the area in the element necessary for the capacitive element. Therefore, a semiconductor device that is further miniaturized than the conventional semiconductor device can be obtained.

  FIG. 6 shows a power supply voltage generation circuit according to the second embodiment of the present invention. The basic configuration of the power supply voltage generating circuit in this embodiment is the same as that of the first embodiment shown in FIG. The difference is that a control circuit is provided and connected to the comparison circuit so that the comparison circuit can be controlled.

In the power supply voltage generation circuit 60, the comparison circuit 61 controls the gate voltage _Vout of the driver circuit 63. That is, the reference voltage _{V ref} sent from the reference voltage generating circuit 62, the resistor _{R 21} and the resistor compares the monitor voltage _{V mon} of the divided internal power supply voltage _{V DD} by _{R 22,} the monitor voltage _{V mon} reference voltage When the level becomes lower than V _ref , the comparison circuit 61 selects the reference voltage V _ref and adjusts the gate voltage V _out so as to increase the current flowing through the driver circuit 63. On the other hand, when the monitor voltage V _mon becomes higher than the reference voltage V _ref , the comparison circuit 61 selects the monitor voltage V _mon and adjusts the gate voltage V _out so as to reduce the current flowing through the driver circuit 63.

In order to perform stable circuit operation, capacitive elements C _DD , C _CC , and C _CD are formed in the power supply voltage generation circuit 60. The supply line for the external power supply voltage _Vcc has a first capacitive element C _CC , the supply line for the internal power supply voltage V _DD has a second capacitive element C _DD , and the switch circuit 64 has a third capacitive element C _CD. Each is connected.

The connection of the switch circuit 64 can be switched to the external power supply side or the internal power supply side. Thus, changing the connection of the third capacitor _{C CD.} That is, the circuit operates in the flash memory to be connected to the power supply voltage generating circuit 60, when the current I _DD flows to the supply line of the internal power supply voltage V _DD, the third capacitor C _CD by switching the switch circuits 64 The capacitor connected to the supply line of the internal power supply voltage V _DD and connected to the external power supply voltage side is reduced only to the first capacitor element _CC . On the other hand, by adding a third capacitor C _CD to the first capacitor C _CC, it increases the capacitance connected to the internal power supply voltage side. The internal power supply voltage V _DD is stabilized by feeding back the capacitance in this way.

  The switch circuit is composed of, for example, a switch switching unit and a control unit, and is the same as that shown in FIGS. 3 and 4 shown in the first embodiment.

  The control circuit 65 controls the comparison circuit 61 by, for example, outputting a signal synchronized with the command of the external input signal as an enable signal for the comparison circuit 61. Therefore, the control circuit is an oscillation circuit such as a ring oscillator as shown in FIG.

  FIG. 8 shows an example of a comparison circuit used in this embodiment as a circuit diagram. A differential amplifier circuit 67 is used as a comparison circuit. FIG. 9 shows a waveform diagram showing a control waveform generated from the comparison circuit. Further, FIG. 10 shows a waveform diagram of current and voltage showing the operating characteristics of the power supply voltage generating circuit in this embodiment.

Comparator circuit shown in FIG. 8 is a differential amplifier circuit 67 operating in the small potential difference between the comparison voltage V _int comparison reference potential V _ref. The control circuit 66 that determines the incorporation of the comparison reference potential V _ref and the comparison voltage V _int into the differential amplifier circuit 67 is a ring oscillator, and is compared with the comparison reference potential V _ref on the basis of the clock oscillated by the ring oscillator. Switches the voltage V _int acquisition.

As shown in FIG. 9, each clock signal for controlling the operation of the differential amplifier circuit 67 is transmitted by the continuous clock of the ring oscillator. Further, as shown in FIG. 10, the comparison reference potential V _ref and the comparison voltage V _int are taken in at the high level edge of φ1. A minute potential difference is amplified at t ₁ , and data “0” or “1” as a comparison result is latched at t ₂ . As a result, if V _out is “0”, V _int is charged until the next clock cycle. At the subsequent high-level edge of φ1, V _ref and V _int are taken. If V _out is “1” at t ₃ , the charging / discharging operation is not performed even if the voltage drop of V _int occurs until the next clock cycle.

The charge and discharge operation stops at the internal power supply voltage V _int in each cycle is repeated by the digital sampling operation. Current consumption is reduced as compared with the conventional analog charge / discharge operation. Therefore, a circuit that consumes a large amount of current and has a high speed becomes possible.

In this embodiment, as in the first embodiment, it is possible to reduce vibrations of the internal power supply voltage V _DD and the external power supply voltage _VCC . Therefore, it is possible to provide a power supply voltage generation circuit with stable operation.

  Further, by switching and utilizing the capacitive element, it is possible to reduce the area in the element necessary for the capacitive element. For this reason, a semiconductor device further miniaturized than before can be obtained.

Further, not only at the time of switching from the standby state to the operation state, but also when the consumption current has a sharp and large change such as an operation mode change by a command signal, the second capacitor connected to the internal power supply voltage side is provided. By changing the frequency, the oscillation of the internal power supply voltage V _DD can be controlled. Thereby, a stable circuit operation can be obtained.

  FIG. 11 shows a power supply voltage generation circuit according to the third embodiment of the present invention. The basic configuration of the power supply voltage generation circuit in this embodiment is the same as that of the second embodiment shown in FIG. The difference is that a conversion circuit is connected to the comparison circuit so as to be compatible with a synchronous memory.

In the power supply voltage generation circuit 70, the gate voltage _Vout of the driver circuit 73 is controlled by the comparison circuit 71a and the conversion circuit 71b. That is, the reference voltage _{V ref} sent from the reference power supply generation circuit 72, resistor _{R 71} and the resistor _{R 72} compares the monitor voltage _{V mon} of the divided internal power supply voltage _{V DD,} the monitor voltage _{V mon} reference voltage When the level becomes lower than V _ref , the comparison circuit 71 a selects the reference voltage V _ref and adjusts the gate voltage V _out so as to increase the current flowing through the driver circuit 73. On the other hand, when the monitor voltage V _mon becomes higher than the reference voltage V _ref , the comparison circuit 71 selects the monitor voltage V _mon and adjusts the gate voltage V _out so as to reduce the current flowing through the driver circuit 73.

Capacitance elements C _DD , C _CC , C _CD are formed in the power supply voltage generation circuit 70 in order to perform stable circuit operation. The supply line for the external power supply voltage _Vcc has a first capacitive element C _CC , the supply line for the internal power supply voltage V _DD has a second capacitive element C _DD , and the switch circuit 74 has a third capacitive element C _CD. Each is connected.

The connection of the switch circuit 74 can be switched to the external power supply side or the internal power supply side. Thus, changing the connection of the third capacitor _{C CD.} That is, the circuit operates in the flash memory to be connected to the power supply voltage generating circuit 70, when the current I _DD flows to the supply line of the internal power supply voltage V _DD, the third capacitor C _CD by switching the switch circuits 74 The capacitor connected to the supply line of the internal power supply voltage V _DD and connected to the external power supply voltage side is reduced only to the first capacitor element _CC . On the other hand, by adding a third capacitor C _CD to the first capacitor C _CC, it increases the capacitance connected to the internal power supply voltage side. The internal power supply voltage V _DD is stabilized by feeding back the capacitance in this way.

  The switch circuit is composed of, for example, a switch switching unit and a control unit, and is the same as that shown in FIGS. 3 and 4 shown in the first embodiment.

  Further, since the control circuit 75 is the same as the ring oscillator of FIG. 7 shown in the second embodiment, it is not shown here and will not be described.

When this power supply voltage generation circuit is applied to a synchronous flash memory, current consumption also increases. Therefore, a circuit for monitoring and changing the internal power supply voltage V _DD is required because the circuit operation of the power supply voltage generating circuit is also synchronous.

  For example, a current mirror type circuit is used as the comparison circuit 71a to which the control circuit 75 is connected. In this case, the output signal is an analog signal. A one-stage inverter circuit is connected to the comparison circuit 71a as the conversion circuit 71b and is converted into a digital signal by, for example, full swing.

  The signal output from the comparison circuit 71a becomes a low level signal by the conversion circuit 71b which is a one-stage inverter circuit, for example, by having a high-level reverse phase.

In the present embodiment, as in the second embodiment, it is possible to reduce vibrations of the internal power supply voltage V _DD and the external power supply voltage _VCC . Therefore, it is possible to provide a power supply voltage generation circuit with stable operation.

  Further, by switching and utilizing the capacitive element, it is possible to reduce the area in the element necessary for the capacitive element. For this reason, a semiconductor device further miniaturized than before can be obtained.

In addition to switching from the standby state to the operating state, the second capacitor connected to the internal power supply voltage side is also used when, for example, a sudden and large change in current consumption occurs, such as an operation mode change due to a command signal. By changing the frequency, the oscillation of the internal power supply voltage V _DD can be controlled. Thereby, a stable circuit operation can be obtained.

  Furthermore, the present invention can be applied to a synchronous memory, which contributes to the expansion of applications.

  FIG. 12 shows a circuit block diagram of a power supply voltage generation circuit according to the fourth embodiment of the present invention. In this embodiment, the application range to the semiconductor device can be expanded by using a plurality of power supply voltage generation circuits.

  The semiconductor device of this embodiment includes five power supply voltage generation circuits 80a, 80b, 80c, 80d, and 80e, and the reference power supply potential generation circuit 82 and the control circuit 85 are common.

In the case of a synchronous memory with a large current consumption, the vibration of the internal power supply voltage V _DD also increases with respect to the current fluctuation. Therefore, in order to stabilize it, an externally input command is input as a feedback signal to the power supply voltage generation circuits 80a, 80b, 80c, 80d, and 80e, the next operation mode is predicted, and the power supply voltage generation circuits 80a, 80b, The power supply capability of 80c, 80d, and 80e can be changed. For this reason, it is possible to supply the internal power supply voltage V _DD having a stability higher than that of a single power supply voltage generation circuit.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The semiconductor device can be applied not only to a flash memory but also to a general semiconductor memory such as a nonvolatile memory and a dynamic random access memory. The power supply voltage generation circuit can be applied not only to a voltage drop circuit but also to a voltage booster circuit.

  Further, the switch circuit may be not only a circuit formation including a switching unit and a control unit, but also a circuit type in which a switch can be automatically switched without using a control signal from the outside only by the switching unit.

  Further, as the comparison circuit, a comparison circuit such as a window comparison circuit or a strobe comparison circuit may be used in addition to the circuit shown in this embodiment.

  In addition, the present invention can be configured as described in the following supplementary notes.

  As a supplementary note 1, a semiconductor device having one or more power supply voltage generation circuits for standby and two or more for operation.

  Supplementary note 2 As voltage control means, the first capacitor connected to the external power supply side, the second capacitor connected to the internal power supply side, and the connection between the external power supply side and the internal power supply side can be switched. And a third capacitor element connected to the switch circuit and switched between the external power supply side and the internal power supply side by the switch circuit.

  As supplementary note 3, the driver circuit is an insulated gate field effect transistor, has a comparison circuit for controlling the gate voltage of the insulated gate field effect transistor, and has a reference potential generating circuit for supplying a reference voltage to the comparison circuit, and a monitor voltage. A semiconductor device having a power supply voltage generation circuit, characterized in that it has two resistors for dividing an internal power supply voltage to be applied, and drops the external power supply voltage to generate an internal power supply voltage.

  Appendix 4 A semiconductor device having a power supply voltage generating circuit, wherein a control circuit is connected to the comparison circuit, and the control circuit controls output from the comparison circuit so as to synchronize with an output signal from the internal power supply voltage side .

1 is a circuit block diagram showing a semiconductor device according to a first embodiment of the present invention. 1 is a circuit block diagram showing a power supply voltage generation circuit according to a first embodiment of the present invention. The circuit block diagram which shows the switch switching part of the switch circuit in 1st Example of this invention. The circuit block diagram which shows the control part of the switch circuit in 1st Example of this invention. FIG. 3 is a current and voltage waveform diagram showing operating characteristics of the power supply voltage generation circuit according to the first embodiment of the present invention. The circuit block diagram which shows the power supply voltage generation circuit in the 2nd Example of this invention. The circuit block diagram which shows the control circuit in the 2nd Example of this invention. The circuit block diagram which shows the comparison circuit in the 2nd Example of this invention. The wave form diagram which shows the control waveform generated from the comparison circuit in the 2nd Example of this invention. FIG. 6 is a current and voltage waveform diagram showing operating characteristics of a power supply voltage generation circuit according to a second embodiment of the present invention. The circuit block diagram which shows the power supply voltage generation circuit in the 3rd Example of this invention. The circuit block diagram which shows the some power supply voltage generation circuit in the 4th Example of this invention. The circuit block diagram of the power supply voltage generation circuit which shows a prior art example. The operation | movement waveform diagram of the power supply voltage generation circuit which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flash memory 11 Memory cell and peripheral circuit 12, 13 Interface circuit 14, 20, 60, 70, 90 Power supply voltage generation circuit 80a, 80b, 80c, 80d, 80e Power supply voltage generation circuit 21, 41a, 41b, 61, 71a, 91 Comparison circuits 22, 42a, 42b, 62, 72, 82, 92 Reference potential generating circuits 23, 40, 63, 73, 93 Driver circuits 24, 64, 74 Switch circuit 30 Switch circuit switching unit 40 Switch circuit control unit 65, 66, 75, 85 Control circuit 67 Differential type amplifier circuit 71b Conversion circuit

Claims (5)

A power supply voltage generation circuit that adjusts an external power supply voltage input from an external power supply to a predetermined voltage via a driver circuit and outputs the internal power supply voltage to an external circuit,
A power supply comprising voltage control means for controlling the internal power supply voltage by changing a capacity connected to the external power supply side and a capacity connected to the internal power supply side during operation of the external circuit. Voltage generation circuit. As the voltage control means,
A first capacitive element connected to the external power supply side;
A second capacitive element connected to the internal power supply side;
A switch circuit capable of switching connection to the external power supply side and the internal power supply side,
2. The power supply voltage generation circuit according to claim 1, further comprising a third capacitor element connected to the switch circuit and switched to the external power supply side or the internal power supply side by the switch circuit.   The driver circuit is an insulated gate field effect transistor, a comparison circuit for controlling a gate voltage of the insulated gate field effect transistor, a reference potential generating circuit for providing a reference voltage to the comparison circuit, and an internal for providing a monitor voltage 3. The power supply voltage generation circuit according to claim 1, further comprising: two resistors that divide a power supply voltage, wherein the external power supply voltage is dropped to obtain the internal power supply voltage. 4.   4. The control circuit according to claim 1, wherein a control circuit is connected to the comparison circuit, and an output from the comparison circuit is controlled so as to be synchronized with an output signal transmitted from the control circuit. The power supply voltage generation circuit described.   An external power supply voltage input from an external power supply is adjusted to a predetermined voltage via a driver circuit, output to an internal circuit as an internal power supply voltage, and connected to the external power supply side during operation of the internal circuit A semiconductor device comprising: a power supply voltage generation circuit including voltage control means for controlling the internal power supply voltage by changing a capacity and a capacity connected to the internal power supply side.

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