JP2643325B2 - Power supply voltage conversion circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply voltage conversion circuit, and more particularly to a power supply voltage conversion circuit that obtains a voltage of a certain value by converting a voltage supplied from an external power supply.

[Conventional technology]

FIG. 6 is a circuit diagram showing an example of a power supply voltage conversion circuit using a conventional differential amplifier.

In FIG. 6, an operational amplifier is used as an example of the differential amplifier. This power supply voltage conversion circuit is used for applications such as charging a bus line having a large load capacity to a certain voltage value and maintaining the voltage value. Explaining the role of each block, first, an external power supply voltage (hereinafter, V _cc ) is converted into a reference voltage (hereinafter, V _REF ) of a desired value by a reference voltage generation circuit 61. The V _REF is input to the inverting input terminal (-) of the operational amplifier 62, and the operational amplifier 62 and the load driver 63 (in the figure, the source is V _CC , the gate is the output of the operational amplifier, and the conversion voltage node whose output is the output of the drain power supply voltage converter circuit) It consists (hereinafter intV _CC connected to the P-channel type MOS transistor), and the maintenance of charge and constant voltage such as a bus line.

For example, when the potential of intV _CC becomes lower than V _REF , the output of the operational amplifier 62 goes to a low level, so that the PMOS transistor of the load driver 63 is turned on to supply current to intV _CC and raise the potential of intV _CC . Conversely, the potential of intV _CC is V _REF
If it becomes higher, the output of the operational amplifier 62 becomes high potential and
Supply of current to tV _CC stops. With this series of operations,
The tV _CC level is kept at the conversion voltage.

However, when a conventional power supply voltage conversion circuit as shown in FIG. 6 is used to charge or maintain a bus line or the like having a large load capacitance to a constant voltage, a large amount of current must be supplied to the differential amplifier. Must. Therefore, it is necessary that the transistor supplying the current to the differential amplifier also has a current driving capability. This is because, for example, when this power supply voltage conversion circuit is applied to the high-level supply of the bit line of the DRAM, the conversion voltage is actually required when the sense amplifier is activated, such as when the sense amplifier is activated. If it is only for a specific period, power consumption during standby is wasted.

As a solution to this problem, a method that has already been used is described in IEE, 1986, Journal of Solid State Circuit, Vol. 21, 5 (IEEE, Journal of Solid State Circuit). vol.SC-21
No.5) Some are shown in Fig.7 on page 608.
In the example of this document, the power supply voltage conversion circuit is applied to supply the bit line potential of the DRAM as described above, and the concept will be described with reference to FIG. FIG. 7 is a circuit diagram showing an improved version of the conventional example shown in FIG. First, when the sense amplifier is activated, that is, when a conversion voltage (3.5 V in this example) is required, the clock φ is set to low level, the transistor Q1 (large conductance) is turned on to supply a large current to the amplifier, and a large load is applied. Drive. On the other hand, when the sensing is completed and the conversion voltage is no longer required, the clock φ is set to the high level, and the current flowing through the amplifier is made only by the transistor Q2 (small conductance), thereby reducing the current consumption.

[Problems to be solved by the invention]

However, in the conventional circuit shown in FIG. 7, the instant at which the transistor Q1 becomes non-conductive, the potential of the output node OUT drops. And the transistor at this time
Since the current supply capability of Q2 is small, the level of the output node OUT does not become high unless the transistor Q1 conducts again. As a result, when the power supply voltage conversion circuit is used next time, the driver transistor QD is conductive, so that the intV _CC level becomes a high potential exceeding the desired conversion voltage. Then, in the example of the application to the memory described above, a higher voltage than necessary is supplied as a conversion voltage to the transistor in the memory cell unit having a small withstand voltage via intV _CC , which causes a serious problem that the transistor is destroyed. .

The object of the present invention is to solve the above problems, and to keep the level of the output node OUT of the operational amplifier at a high level even when the power supply voltage conversion circuit is inactivated by an internal switch,
An object of the present invention is to provide a power supply voltage conversion circuit that keeps the intV _CC level at a constant voltage by keeping the driver transistor QD non-conductive.

[Means for solving the problem]

A power supply voltage conversion circuit according to the present invention includes a reference voltage generation circuit, a differential amplifier, and a load drive circuit, and outputs an output from the reference voltage generation circuit to one input terminal of the differential amplifier and another input terminal. The differential amplifier controls the operation / non-operation of the differential amplifier in a power supply voltage conversion circuit in which the output of the power supply voltage conversion circuit is input as feedback to the input of the load drive circuit. And a switch for preventing the load drive circuit from operating when the differential amplifier is not operating.

[Action]

The power supply voltage conversion circuit of the present invention, when a conversion voltage is required,
This circuit is activated by an internal switch to supply a constant voltage, and conversely, when no conversion voltage is required, the internal switch is shut off to deactivate the circuit and save current flowing through the circuit. The internal switch is provided so as not to operate the circuit of (1). As a result, when the power supply voltage conversion circuit is inactive, an unnecessarily high potential is not applied to the conversion voltage node, which is the output of the circuit, to reduce power consumption and to reduce the power consumption of the circuit incorporating the power supply voltage conversion circuit. Normal operation is guaranteed.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

1, 2 and 3 are circuit diagrams showing first, second and third embodiments of a power supply voltage conversion circuit according to the present invention, and FIGS. 4 and 5 are power supply voltage conversion circuits according to the present invention. FIG. 4 is a circuit diagram showing first and second examples of a differential amplifier used in a circuit.

The first embodiment shown in FIG. 1 and the second embodiment shown in FIG.
Example using a current mirror type amplifier that is
In the third embodiment shown in the figure, the differential input section is an N-channel type MISF.
This is an example using a current mirror type amplifier such as an ET.

First, in FIG. 1, the first block amplifies the difference voltage between intV _CC of the output of this circuit and V _REF generated by the reference voltage generation circuit 11, and the second block amplifies the difference voltage between the intV _CC of the output of this circuit and the V _REF generated by the reference voltage generation circuit 11. And output differential amplifier 12, third
Is a driver circuit 13 that supplies a current to the node of intV _CC and drives a load. The reference voltage generation circuit may be any type of circuit as long as it converts the externally applied V _CC to provide a certain value of V _REF . Also,
In the first embodiment, a current mirror type amplifier constituted by a MISFET is used as the differential amplifier. However, in practice, any circuit may be used as long as it is a differential amplifier, and a bipolar amplifier as shown in FIG. An amplifier composed of a transistor may be used, or an amplifier using a non-current mirror type constant current circuit as shown in FIG. Also,
An amplifier constituted by a circuit combining a bipolar transistor and a MISFET may be used. In the example shown in FIG. 5, a simple resistor R is used as the constant current circuit section 51 of the amplifier. The driver circuit is a circuit for supplying a current from an external power supply to the internal power supply line intV _CC . In the first embodiment, a P-channel MISFET is exemplified. However, a bipolar transistor or a circuit including a plurality of transistors may be used.

 Here, the characteristic points of the present invention will be described.

In the first embodiment, the driver for controlling the operation / non-operation of the power supply voltage conversion circuit is a P-channel type MISFET.
In the case of (1), it is provided between the output node of the differential amplifier and the ground point. By doing so, one of the gist of the present invention is that “the load drive circuit does not work when the differential amplifier is inactive”.
You have achieved one of the structures. Conversely, if the driver is an N-channel MISFET, a switch is inserted between the differential amplifier output node and the power supply. Similar considerations apply when using bipolar drivers. In the present embodiment, the operation / non-operation of the power supply voltage conversion circuit is set to the source connected to the ground point, the drain connected to the node connected to the ground point (in the case where the switch of the present invention is not provided) and the gate. An N-channel MISFET in which a clock φ to be controlled is input corresponds to the switch QSW. With such a switch, the potential of the output node OUT of the operational amplifier when the QSW becomes nonconductive high, the driver transistor QD has does not flow current to intV _CC becomes non-conductive. Second
This embodiment is an example in which switches are provided by a method different from that of the first embodiment. In this embodiment, switches QSW and QSW 'for controlling the operation / non-operation of the power supply voltage conversion circuit are provided between the differential input section of the differential amplifier 22 and the constant current circuit section. Also in this embodiment, the switch QSW and QSW' is flow no current into intV _CC when rendered non-conductive.

The third embodiment differs from the first and second embodiments in that the current supply transistor Q1 to the operational amplifier is located between the differential portion and the ground point. When an operational amplifier of this type is used, in a conventional example in which the driver circuit 13 of the P-channel MISFET is driven, the current supply transistor Q1 to the operational amplifier can directly serve as a control switch of the power supply voltage conversion circuit, and the current supply transistor Q1 Can be used as a switch for controlling the activation / inactivation of the power supply voltage conversion circuit by inputting the clock φ to the gate of
The effect of the present invention can be obtained without adding a transistor to the conventional power supply voltage conversion circuit as in the first or second embodiment.

〔The invention's effect〕

As is apparent from the above description, by using the power supply voltage conversion circuit of the present invention, the power consumption can be significantly reduced as compared with the conventional power supply voltage conversion circuit. In other words, in the application of the present power supply voltage conversion circuit to the memory described in the section of “Prior Art”, current is consumed only when charging the bit line that requires this circuit, and in other cases, the current is consumed due to transistor leakage or the like. Since the current consumption becomes zero if a very small current is ignored, the power consumption can be greatly reduced as compared with the conventional power supply voltage conversion circuit. At the same time, an effect is obtained that a constant voltage can be supplied without applying an unnecessarily high potential at the time of switching between activation and deactivation of the power supply voltage conversion circuit.

[Brief description of the drawings]

1, 2 and 3 are circuit diagrams showing first, second and third embodiments of a power supply voltage conversion circuit according to the present invention, and FIGS. 4 and 5 are power supply voltage conversion circuits according to the present invention. Of the differential amplifier used in the circuit
1, a circuit diagram showing a second example, FIG. 6 is a circuit diagram showing an example of a power supply voltage conversion circuit using a conventional differential amplifier, and FIG. 7 is an improved version of the conventional example shown in FIG. FIG. 11 Reference voltage generation circuit, 12, 22, 32 Differential amplifier, 13 Driver circuit, 41, 51 Constant current circuit section, 4
2 ... Differential input section, QSW, QSW '... Switch, Q1 ... Current supply transistor, QD ... Driver transistor.

Claims (1)

(57) [Claims] An output from the reference voltage generating circuit is provided to one input terminal of the differential amplifier, comprising a reference voltage generating circuit, a differential amplifier, and a load drive circuit.
In the power supply voltage conversion circuit, the output of the power supply voltage conversion circuit is fed back to the other input terminal, and the output of the differential amplifier is used as an input of the load drive circuit.
The differential amplifier includes a switch for controlling the operation / non-operation of the differential amplifier, and the switch is provided so that the load drive circuit does not operate when the differential amplifier is not operating. Power supply voltage conversion circuit.