JPS63121467A - Internal voltage divider - Google Patents

Abstract

PURPOSE:To reduce power consumption, by composing a circuit of a plurality of voltage-dividing capacitors, voltage-retaining capacitors, and switches in order to supply transistor(s) with power from the capacitor circuit. CONSTITUTION:An internal voltage divider is provided with two voltage-dividing capacitors C1, C2 arranged between power voltage Vdd1 and voltage to ground, a voltage-retaining capacitor Cs, and five switches S1-S5 converting the connecting relation of these capacitors, and is composed of the Barton circuit with differential amplifiers M1-M4 and a driving transistor M5. Then, the voltage-dividing capacitors C1, C2 are used first, and potential difference between the capacitors and ground is divided and retained. After that, by control signal, the switches S1-S5 are controlled, and are connected so that divided and retained voltage may be set in parallel with each other, and the voltage is fed to the voltage-retaining capacitor Cs. To the capacitor Cs, the driving transistor M5 is connected, and desired voltage can be fed.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention relates to an internal step-down circuit used in a semiconductor integrated circuit to step down a power supply voltage and supply the stepped-down voltage to other circuits, and in particular, relates to an internal step-down circuit used in a semiconductor integrated circuit to step down a power supply voltage and supply the stepped down voltage to other circuits. This invention relates to an internal step-down circuit that reduces power consumption.

In the internal step-down circuit for supplying the voltage, the power supply voltage is divided by a power supply voltage dividing means composed of a plurality of capacitors and switches, and the divided voltage is supplied to the driving transistor. This reduces power consumption in the driving transistor.

C0 Conventional technology Generally, in semiconductor integrated circuit devices such as DRAM,
As the capacity increases, the miniaturization of each memory cell, etc. is progressing.

Incidentally, when such miniaturization is advanced, it becomes necessary to lower the power supply voltage Vcc internally in order to prevent the adverse effects of hoft electrons and the like on the transistors of the cells.

For example, a circuit as shown in FIG. 4 is known as an internal step-down circuit for stepping down the power supply voltage Vcc and supplying the stepped-down voltage to other circuits in response to such a request. The step-down circuit will be briefly explained.

As shown in FIG. 4, the conventional internal step-down circuit includes other circuits (for example, DRAM) within one chip surrounded by a dotted line in the figure.
A power supply voltage VddL (for example, 5 V) is supplied from outside the chip through terminals 41 and 42 in common with the I10 circuit 40. This internal step-down circuit mainly has a Burton circuit configuration using the reference step-down power supply Vddz as an input, and includes transistors M43 and M43, which constitute a differential transistor pair.
M44 and transistor M4 forming a current mirror
5. M46, a constant current source io, and a driving transistor M47. The gate of the driving transistor M47 is connected to the drain of the transistor M44, and the gate of the transistor M44 is connected to the source of the driving transistor M47. It is connected to a low voltage operation circuit 48.

Such a conventional internal step-down circuit can function as a stable regulator, and the M current I L is supplied to the low voltage operation circuit 48 through the driving transistor M47.
The voltage is injected into the low voltage operation circuit 48 and operates to drive the low voltage operation circuit 48.

D1 Problem to be Solved by the Invention However, in the above-mentioned internal voltage step-down circuit, a problem arises in that power is consumed due to the voltage drop caused by the drive transistor M47, and this becomes a technical problem to be solved. ing.

That is, when considering the power consumption based on the drain current ■L flowing through the driving transistor M47, the power PW1 (=ILXVdd2) required to drive the low voltage operation circuit 48 as a load is Although it is effectively used during operation, on the other hand, the power supply voltage Vdd is supplied to the drain of this driving transistor M47, and the power PW2 in this driving transistor M47 is
(-ILX (Vddx -Vddz)) is
It is simply wasted in the driving transistor M47 (that is, without contributing to driving the load), and becomes a waste.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an internal step-down circuit that reduces power consumption in a driving transistor.

Means for Solving the E1 Problem The present invention provides an internal step-down circuit for stepping down the voltage 1112%i and supplying the stepped-down voltage to other circuits. It has a dividing capacitor, a voltage holding capacitor, and a plurality of switches for converting the connection relationship between the voltage dividing capacitor and the voltage holding capacitor,
These multiple switches are opened and closed by control signals,
The above-mentioned problem is solved by an internal step-down circuit characterized by holding the voltage obtained from each voltage dividing capacitor in the voltage holding capacitor and supplying it to the driving transistor.

F6 action In the internal step-down circuit of the present invention, first, a plurality of voltage dividing capacitors arranged between the power supply voltage and the ground voltage are used to divide the potential difference between the power supply voltage and the ground voltage, and the voltage dividing capacitor is divided into the voltage dividing capacitors. to hold. Next, a switch is controlled by a control signal to connect and convert the voltage dividing capacitors each having each voltage divided and held in parallel, and the voltage divided and held by these voltage dividing capacitors is connected in parallel. Supply voltage to the voltage holding capacitor. This voltage holding capacity has
The drain (or source) of the driving transistor is connected, so that the driving transistor is eventually supplied with the required voltage from the divided and stepped-down voltage holding capacitor. Therefore, it is possible to reduce the potential drop in the driving transistor, and its power consumption can be reduced.

G. Example Preferred embodiments of the present invention will be described with reference to the drawings.

First Embodiment The internal step-down circuit of this embodiment converts the connection relationship between a plurality of voltage dividing capacitors and voltage holding capacitors using a switch.
This is an internal step-down circuit that supplies the stepped-down voltage to the driving transistor to achieve low power consumption, and uses two voltage-dividing capacitors.

As shown in FIG.
Two voltage dividing chamber ICs placed between dd1 and ground voltage! , C2, voltage holding capacitor IC5, and five switches 31, 52 . S3.
S4. The main component is a circuit portion having a Burton circuit configuration including a differential amplifier and a driving transistor M5.

That is, first, in the internal step-down circuit of this embodiment, a predetermined power supply voltage Vdd1 is supplied from the outside of the chip from the terminal 11.12, and within the chip, the power supply voltage Vcld is supplied to, for example, the I10 circuit 13, etc. A portion is supplied to a differential amplifier configured as a Burton circuit. The terminal 11 is connected to one end of the voltage division chamber fi CL at a connection point P1 via a switch SL, and the other end of this voltage division chamber RC1 is connected to a switch S2 at a connection point P2.

This switch S2 is further connected to the voltage dividing chamber at the connection point P3.
51 Connected to one end of C2, this voltage division chamber i C
The terminal 12 is connected to the other end of *, and is set to the ground voltage. Here, the voltage dividing chamber ffi Cl and the voltage dividing capacitor C2 have the same capacitance value,
Both the switch S1 and the switch S2 are controlled by a control signal Φ1, which will be described later. In this way, between the power supply voltage Vddx and the ground voltage, the switch S1
and when switch S2 is on, two voltage dividing chambers ic1. Since C2 is connected in series, the potential difference can be divided and held as described later.
In particular, since the capacitance values of the two voltage dividing chambers 1cI and C2 are the same, the voltage held in each is Vddx/2.

In addition, two voltage division chambers M having such a connection relationship
Cx, C2 are further connected to switches S3. It is connected to the voltage holding capacitor Cs via S4 and Ss. That is, the voltage holding capacitor i1Cs, which has the function of holding a voltage and supplying the held voltage to the driving transistor M5 of the Burton circuit configuration, is connected to the driving transistor M5 at the connection point Pa (P4'), It is connected to a connection point P1 at one end of the voltage division chamber MCL via a switch S3, and connected at its connection point P4 to a connection point P3 at one end of the voltage division chamber IC2 through a switch S5. There is.

The other end of this voltage holding capacitor 1i Cs is grounded and connected to the other end of the voltage dividing capacitor C2, and is also connected to the connection point P2 at the other end of the voltage dividing chamber IC1 via a switch S4. Connected.

Here, the above-mentioned switches 33.34. Ss is controlled by a control signal φ2 as described later. Ill signal Φ1
When the switches SL and 32 are turned off by the control signal Φ2 and the switches 33, 34, and 35 are turned on by the control signal Φ2,
The voltage dividing chamber lIc1. C2 and the voltage holding capacity Cs are connected in parallel, and the stepped down voltage can be supplied to the driving transistor M5 to achieve low power consumption.

Next, the differential amplifier having a Burton circuit configuration has a current mirror configuration with transistors M1 and M2 whose sources are commonly connected to the constant current source 11 and which constitute a differential transistor pair, and whose sources are connected to the above N'tA voltage. It consists of transistors M3 and M4 commonly connected to Vddz. This transistor M1 is, for example, a Divry Chiron type M
The transistor M2 is an enhancement type MOSFET, for example. Therefore, the gate potential of the transistor M2 can be stabilized to the potential Vdd2 corresponding to the difference between the threshold voltages vth of the transistors M1 and M2 via the driving transistor M5 serving as a feedback loop. Note that a circuit configuration in which a reference voltage is input may be used.

The driving transistor M5, which constitutes the Burton circuit and forms a feedback loop, has a function of supplying current for driving a load. In particular, the driving transistor M5 in the internal step-down circuit of this embodiment , the power supply side is connected to one end of the voltage holding field IJ Cs and the connection point P4 as described above.
(P4'). Therefore, the driving transistor M5 is not directly supplied with the voltage 'a'a Vdd, but is supplied with a lower voltage Vdd3 which is divided and stepped down, as will be described later.

The source side of this driving transistor M5 is connected to the gate of the transistor M2 of the differential amplifier, and is also connected to a low voltage operation circuit 14 such as a sense amplifier or memory cell of a DRAM.

Next, the operation of the internal voltage step-down circuit of this embodiment will be explained with reference to FIG.

First, as a premise, there is a voltage V between terminal 11 and terminal 7-12.
dd1 is given, and the output voltage of the differential amplifier is Vdd, and it is assumed that Vdd<Vdd1/2. As shown in FIG. 2, the control signal Φ1. A control signal φ2 is applied.

Control <B (f bone medium 1 becomes high level, switches SL and 32 controlled by this control signal Φ1 are turned on, and at this time, control signal Φ2 is low level and switches S3, S4, and S5 are turned off. In this case, the circuit connection relationship is such that the voltage dividing capacitors C1 and C2 are connected in series between the power supply voltage Vdd1 and the ground voltage, and in particular, the potential difference and voltage in the voltage dividing capacitor C1 are The potential differences in the dividing capacitor C2 are equal to each other, that is, Vdd1/2.The voltage dividing fields 1tch and C2, where the divided voltages are held, are set when the switches S3, S4, and Ss are turned off. Therefore, in this connection relationship, the driving transistor M5 is not supplied with the voltage Vdd3 already held in the voltage holding capacitor C9. Operate.

Next, the control signal Φ1 becomes low level, and the switches S1. S2 is turned off, and when the control signal φ2 becomes high level, the switches S3. S4 and 35 are turned on. Regarding the circuit connections in this case, the voltage division field 1tCt is the switch S3. By turning on S4, connection points P1 and P4'
and the connection point P2 and the ground potential are short-circuited, and
Voltage dividing capacitor C2 has three capacitors JICx because connection points P3 and P4 are short-circuited when switch S5 is turned on.
, C2 and the voltage holding field 1ics are connected in parallel. At this time, the voltage dividing fields ffi C1 and 02 are already charged with a voltage of Vddx/2 when the control signal Φl is at a high level, as described above, and are charged by the operation of the switches 31 to S5. Charge redistribution occurs to the voltage holding capacitor C9.

Here, in this case, the voltage of the voltage holding field fJ Cs, that is, the voltage V supplied to the driving transistor M5
dd3 is the voltage dividing capacitor c1. Since redistribution occurs when c is connected in parallel with the voltage holding capacitor C8, if the leakage voltage is ΔV in one cycle of the voltage holding field i1 Cs, then Vdds max JVddz /2) −(CsΔV
)/Σc ・−■(°, ゛ΣC=CL +C:, +C
8), and hereafter, from this Vdd3maχ (maximum value), as shown in FIG. When 33 to S5 are off, the curve B changes exponentially with each time constant. Here, the leakage voltage Δ■ is the potential difference when the voltage Vd becomes the smallest from the voltage Vdd1/2, but the leakage voltage Δ■ is the potential difference when the voltage Vd becomes the smallest from the voltage Vdd1/2. By setting the clock cycle of Φ2 to a low speed, it can be made sufficiently small.

Voltage Vddx supplied to this driving transistor M5
When compared with the conventional power consumption, (Vddl-
It can be seen that low power consumption of I L > Vdd1/2 can be achieved, and the driving transistor M5 can be driven with the minimum voltage.

Note that in the internal step-down circuit of the first embodiment described above, the configuration of the differential amplifier is not particularly limited, and may be other reference voltage circuits, buffer circuits, or the like.

Second Embodiment The internal step-down circuit of this embodiment converts the connection relationship between a plurality of voltage dividing capacitors and voltage holding capacitors using a switch.
This is an internal step-down circuit that supplies the stepped-down voltage to the driving transistor to achieve low power consumption, and uses three voltage-dividing capacitors.

As shown in FIG. 3, this internal voltage step-down circuit
dd, and the ground voltage, and have the same capacitance value, three voltage dividing capacitors IC1, C2, C3, voltage holding capacitor C3, and these voltage dividing capacitors IC1, C2, C2
, C3 and the voltage holding capacitor Cs, eight switches T1, T2 . Ts, T4. Ul, U
2. U3. The main component is a circuit portion having a Burton circuit configuration including a differential amplifier and a driving transistor M5. In addition,
Among the above switches, switches Ti, T2 . T3, T
The switches 01.4 are opened and closed by the control signal Φ1, and the switches 01.
U2. U3. U4 is opened and closed by control signal Φ2.

Here, these capacitors C1, C2, C3 and eight switches T1, 72 . Tco, T4. Ul,'U2.

U3. To explain the connection relationship of U4, the power supply voltage V
A voltage dividing capacitor WkC1 is connected to the terminal 11 to which d+b is supplied via a switch T1, and a voltage dividing capacitor IC3 is connected via a switch T3. Furthermore, this voltage division term 1
cx and Cs are respectively switches T2. It is connected to one end of the voltage division term 1i C2 via T4, and the other end of this voltage division term 1G2 is connected to the terminal 12 and grounded.

Next, switches Ul, U2 . U3. The UJI is provided in the middle of each loop for converting the connection relationship, and the switch U1 connects and connects between the switch T1 side of the voltage division term IC1 and the switch T4 side of the voltage division term 51C3. The switch U2 is arranged to connect and disconnect between the switch T2 side of the voltage division terminal NC1 and the ground potential terminal 12, and the switch U3 is connected to the voltage division terminal i1 Cz.
The switch U4 is disposed intermittently between the switch T3 side of the voltage holding capacitor 1iCs and the drive transistor M5 side of the voltage holding capacitor 1iCs, and the switch U4 is connected to the switch T2... of the voltage dividing capacitor C2. T.J.
The voltage holding capacitor C5 is connected to the drive transistor M5 side of the voltage holding capacitor C5.

Note that other circuit parts are the same as those in the first embodiment, so detailed explanations will be omitted. Further, although the reference voltage E (E=Vdd2) is used as the input voltage of the differential amplifier, it goes without saying that a combination of enhancement type and depletion type transistor pairs may be used.

The internal step-down circuit of the second embodiment having such a configuration includes the switches TL, T2 . T3. T4 has a control signal Φ
1 is supplied and controlled, and the switch 01. U2. U
3. U4 is supplied with a control signal Φ2 and operates under control. Note that the control signal Φ1. φ2 is a signal similar to that shown in FIG.
Operating voltage Vdd2 of low voltage operating circuit 14 and power supply voltage Vd
This is a circuit in which the relationship of dt is Vddz < 2 Vddt/3.

First, the control signal Φ1 is at high level, and the control signal Φ2
is at a low level, the switches TL and T2
．． T3. Ta is on, and the switches Ul, U2 .
[3, U4 is off.

In this connection relationship, as mentioned above, each field 1c1, C
Since capacitance values of ftc1.1 and C3 are equal, the voltage dividing words ftc1.1 and C3 are in a parallel relationship. The voltage V is applied to c3, respectively.
ddt/3 is charged, while the voltage dividing capacitor C2
will be charged with a voltage 'l Vddx/3.

Next, l in control signal 13 is at low level, and control signal φ
2 is at a high level, the above Sui Nochi Tl
, T2, T3, and T4 are off, and the switch U
t+ U2. Lh and U4 are on.

In this connection relationship, the voltage division term FilCx.

The parallel direct reading relationship of Cs becomes a series connection relationship by a loop via switch U1, and as a result, the voltage division term Et C
2, and the voltage dividing capacitors Cx and Cz connected in series.
The composite capacitor Cs and the voltage holding capacitor Cs are converted into a parallel connection relationship.

In this case, the value of the voltage Vdd3 supplied to the driving transistor M5 is as in the operation in the first embodiment described above, where the leakage voltage is Δ■ and its maximum value is Vdds 1Ilax = (2Vddx /3L (C
sΔV)/Σc−■(°, °ΣC=C2+C8+CI
G3/(C1+C3)). Also, this voltage Vd
The value of d3 decreases exponentially from the maximum value above, but
Redistribution occurs when the control signal Φ2 goes high again, and by speeding up the clock cycle, Δ
V can be made small, and the voltage Vdd3 supplied to the driving transistor M5 can be made smaller than the power supply voltage Vdd, thereby making it possible to sufficiently reduce power consumption.

Note that the configuration of the differential amplifier δ in the internal step-down circuit of the second embodiment described above is not particularly limited, and may be other reference voltage circuits, buffer circuits, or the like.

Furthermore, in the first and second embodiments described above, the voltage dividing capacitors C1, C2, (Cs) have the same capacitance value, but depending on the design, they may have different capacitances. Also good. Furthermore, the connection relationships among the plurality of voltage dividing capacitors and switches described in the first and second embodiments are not limited to those illustrated, and the power supply voltage Vdd1 is adjusted to a predetermined voltage value by operating the control signal. Any connection relationship that divides is fine.

H1 Effects of the Invention The internal voltage step-down circuit of the present invention has a circuit configuration consisting of a plurality of voltage dividing capacitors, a voltage holding capacitor, and a plurality of switches, and is operated by a control signal to convert the connection relationship to a predetermined value. A step-down voltage can be supplied to the driving transistor. Therefore, the voltage supplied to the driving transistor is the minimum necessary, and therefore, the power consumption can be kept sufficiently low.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of the internal step-down circuit of the present invention, FIG. 2 is a waveform diagram for explaining its operation, and FIG. 3 is a circuit diagram showing another example of the internal step-down circuit of the present invention. FIG. 4 is a circuit diagram showing an example of a conventional internal voltage down converter. C1, C2, Cs...Capacitor for voltage division C8...
...Voltage holding capacitors S1 to S5. T1-T4.
U1~U4...Switch M5...Drive transistor

Claims (1)

[Claims] In an internal step-down circuit for stepping down the power supply voltage and supplying the stepped down voltage to other circuits, a plurality of voltage dividing capacitors and a voltage holding capacitor are provided between the power supply voltage and the ground voltage. , a plurality of switches for converting the connection relationship of these voltage dividing capacitors and voltage holding capacitors, and the plurality of switches are opened and closed by control signals,
An internal step-down circuit characterized in that a voltage obtained from each voltage dividing capacitor is held in the voltage holding capacitor and is supplied to a driving transistor.