KR20070006156A - Voltage boost circuit using negative voltage and driving voltage generator including the same - Google Patents

Abstract

A voltage boost circuit using a negative voltage and a driving voltage generator comprising the same are provided to prevent the efficiency decrease of a driving voltage due to a load current without increasing the area of a transistor, by generating a boost voltage from the negative voltage. In a voltage boost circuit for boosting a power supply voltage and outputting a boost voltage through an output stage, at least one boost capacitor(C11,C12) stores a difference voltage between a first power supply voltage applied to an input stage of the voltage boost circuit and a second power supply voltage applied through one port of the voltage boost circuit. At least one switching device(SW10,SW11,SW12,SW13) controls its connection state to store a voltage in the boost capacitor during a first period, and controls its connection state to output the boost voltage by boosting the first power supply voltage as much as the voltage stored in the boost capacitor during a second period. The second power supply voltage is a negative voltage.

Description

Voltage boost circuit using negative voltage and driving voltage generator including the same}

1 is a circuit diagram showing an example of a conventional voltage boost circuit.

2 is a circuit diagram illustrating a voltage boost circuit according to an embodiment of the present invention.

3 is a circuit diagram illustrating a driving voltage generator according to an exemplary embodiment of the present invention.

4 is a circuit diagram illustrating a driving voltage generator according to the present invention in consideration of a resistance component.

5 is a graph showing the efficiency of the driving voltage output from the driving voltage generator according to the present invention in comparison with the prior art.

Explanation of symbols on the main parts of the drawings

VCI: first power supply voltage -Vx: second power supply voltage

C11: Boost Capacitor C12: Output Capacitor

SW10 to SW13: first to fourth switch elements

10: voltage distribution circuit 20: voltage inversion circuit

30: voltage boost circuit 40: comparator

The present invention relates to a voltage boost circuit used in a semiconductor device and the like and a driving voltage generator having the same, and more particularly, by boosting a power supply voltage using a negative voltage, thereby improving efficiency of the generated driving voltage. The present invention relates to a voltage boost circuit and a driving voltage generator having the same.

In addition to improving the integration density of semiconductor devices, studies are being actively conducted to operate circuits at low operating voltages to reduce power consumption. However, if necessary, an operation voltage higher than an applied power supply voltage may be required to operate the device. To this end, the power voltage must be boosted to generate a high operating voltage. A voltage boost circuit is a circuit that can receive a predetermined power supply voltage and boost it to obtain a high output voltage.

In general, a driving voltage used for a mobile display driver IC (DDI) uses a boost voltage output from the voltage boost circuit. A voltage boost circuit for generating the driving voltage will be described with reference to FIG. 1.

1 is a circuit diagram showing an example of a conventional voltage boost circuit. In particular, FIG. 1 illustrates a voltage boost circuit that receives a power supply voltage and doubles it.

As shown in the drawing, a conventional voltage boost circuit receives an input voltage VCI through an input terminal and outputs a boost voltage generated by boosting it to the outside through an output terminal. The boost voltage is a driving voltage AVDD used for a driving IC or the like.

The voltage boost circuit includes at least one capacitor and at least one switch element to boost the power supply voltage VCI. In addition, a reference voltage Vss is applied to one end of the voltage boost circuit, and a positive power supply voltage lower than the input voltage VCI may be applied to the reference voltage Vss. In addition, the reference voltage Vss may generally be a ground voltage.

1 illustrates a voltage boost circuit including two capacitors C1 and C2 and four switch elements SW1 to SW4 to double the input voltage VCI. One capacitor C1 of the two capacitors is a boost capacitor that stores a voltage corresponding to a value to be boosted, and the other capacitor C2 is an output capacitor connected to an output terminal of the voltage boost circuit.

The operation of the voltage boost circuit as described above is as follows.

First, the four switch elements SW1 to SW4 are controlled by a predetermined control signal so that the first switch element SW1 and the third switch element SW3 are turned on, and the remaining second switch elements SW2 are turned on. ) And the fourth switch element SW4 are turned off.

At this time, the boost capacitor C1 stores a voltage corresponding to the difference between the input voltage VCI and the reference voltage Vss. That is, since the voltages at both ends of the boost capacitor C1 are VCI and Vss, respectively, the voltage corresponding to VCI-Vss is stored in the boost capacitor C1.

Thereafter, the first switch element SW1 and the third switch element SW3 are turned off, and the remaining second switch element SW2 and the fourth switch element SW4 are turned on. In this case, the voltage applied to the output terminal is a voltage corresponding to the sum of the voltage stored in the boost capacitor C1 and the input voltage VCI. Accordingly, the output capacitor C2 is applied to 2 × VCI-Vss. The corresponding value is stored. That is, the boost voltage output through the output terminal is 2 x VCI-Vss, and when the reference voltage Vss is the ground voltage, the boost voltage is 2 x VCI. This means that the voltage boost circuit doubles the input voltage and outputs a boost voltage.

However, in general, a voltage boost circuit in a mobile-oriented display driver IC (DDI) has a boost generated by the voltage boost circuit because the reference voltage Vss is generally fixed to a predetermined positive voltage or ground voltage. The voltage was fixed at or below a certain level than twice the input voltage (VCI). In particular, there is a problem that the efficiency of the generated driving voltage AVDD is lowered due to the voltage drop caused by the load current.

In order to improve the efficiency of the driving voltage AVDD, an area of a transistor element in a voltage boost circuit is increased or an effective layout is required. In the case of improving the efficiency in this manner, it is disadvantageous to high integration of the semiconductor device including the voltage boost circuit, and the layout becomes difficult.

The present invention is to solve the above problems, by generating a boost voltage using a negative voltage, thereby improving the problem that the efficiency of the driving voltage due to the load current is reduced without increasing the area of the transistor It is an object of the present invention to provide a voltage boost circuit capable of doing so.

According to an embodiment of the present invention, a voltage boost circuit includes a first power supply voltage applied to an input terminal of the voltage boost circuit and a second power supply voltage applied through one terminal of the voltage boost circuit. At least one boost capacitor for storing a voltage corresponding to a difference between the at least one boost capacitor, and a connection state of the boost capacitor is controlled to store the voltage in the boost capacitor during the first period, and the first power supply voltage to the voltage stored in the boost capacitor during the second period. And at least one switch element whose connection state is controlled such that the boost voltage is output by boosting by a corresponding value, wherein the second power supply voltage is a negative voltage.

The at least one switch may include a first switch element and a second switch element connected in parallel with the first power supply voltage, respectively, a third switch element connected between the second switch element and the second power supply voltage, and the A fourth switch device may be provided between the first switch device and the output terminal.

The boost capacitor may be connected between the common node of the first switch element and the fourth switch element, and the common node of the second switch element and the third switch element.

On the other hand, the driving voltage generator according to an embodiment of the present invention, a voltage distribution circuit for dividing a first power supply voltage, a voltage inversion circuit for receiving and inverting and outputting a voltage from the voltage distribution circuit, and the first power supply A voltage boost circuit for boosting and outputting the first power supply voltage by a voltage corresponding to a difference between a voltage and a predetermined second power supply voltage and a boost voltage fed back from the voltage boost circuit and an output voltage of the voltage distribution circuit, And a comparator for generating a signal for controlling the voltage boost circuit, wherein the second power supply voltage is a negative voltage.

The second power supply voltage is preferably a negative voltage output from the voltage inversion circuit.

DETAILED DESCRIPTION In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings that illustrate preferred embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

2 is a circuit diagram illustrating a voltage boost circuit according to an embodiment of the present invention. As shown, the voltage boost circuit includes one or more capacitors and one or more switch elements. In addition, a first power supply voltage VCI is applied to an input terminal of the voltage boost circuit, and a second power supply voltage -Vx is applied through one terminal of the voltage boost circuit. The first power supply voltage VCI is generally a positive voltage.

The one or more capacitors may include a boost capacitor and an output capacitor, and the voltage boost circuit of FIG. 2 includes two capacitors C11 and C12. The first capacitor C11 is a boost capacitor, and the boost capacitor stores a voltage corresponding to a difference between the first power voltage and the second power voltage.

In addition, the output capacitor may further include a second capacitor C12, which is connected to an output terminal of the voltage boost circuit to store an output voltage.

Meanwhile, the voltage boost circuit includes one or more switch elements, and the voltage boost circuit of FIG. 2 shows four switch elements as an example. The switch element is controlled on / off by a predetermined control signal (not shown). In particular, the connection state is controlled to store the voltage in the boost capacitor during the first period, and the boost voltage is output by boosting the first power voltage VCI by a value corresponding to the voltage stored in the boost capacitor during the second period. The connection state is controlled as much as possible. The boost voltage may be used as a driving voltage AVDD used in a driving IC.

In particular, in order to achieve the object of the present invention, the second power supply voltage (-Vx) is characterized in that the negative (negative) voltage. Accordingly, the voltage boost circuit may increase the boost ratio of the first power voltage VCI by more than twice, which will be described below.

Referring to the voltage boost circuit of FIG. 2, the four switch elements include a first switch element SW10 and a second switch element SW11 connected in parallel with the first power voltage VCI, and the second switch element. The third switch element SW12 connected between the switch element SW11 and the second power supply voltage (-Vx) and the fourth switch element SW13 connected between the first switch element SW10 and the output terminal are connected. Equipped.

In addition, the boost capacitor C11 may include a common node of the first switch element SW10 and the fourth switch element SW13, and the second switch element SW11 and the third switch element SW12. It is connected between common nodes.

In the voltage boost circuit configured as described above, the first switch element SW10 and the third switch element SW12 are turned on during the first section, and the second switch element SW11 and the fourth switch element ( SW13) is turned off. Accordingly, the boost capacitor C11 stores the voltage VCI + Vx corresponding to the difference between the first power supply voltage VCI and the second power supply voltage −Vx.

Thereafter, the first switch element SW10 and the third switch element SW12 are turned off during the second section, and the second switch element SW11 and the fourth switch element SW13 are turned on. Accordingly, the voltage at the output terminal becomes a value (2VCI + Vx) obtained by adding the voltage stored in the boost capacitor C11 and the first power voltage VCI.

As described above, in the voltage boost circuit of the present invention, since the second power supply voltage (-Vx) is made of a negative voltage, the voltage boosting ratio of the voltage boost circuit may be more than doubled. Therefore, even if a voltage drop occurs due to a load current, the boost voltage output through the output terminal of the voltage boost circuit can be maintained at a constant level.

Meanwhile, the voltage boost circuit as described above may be applied to a driving voltage generator for generating a driving voltage used for a mobile display driver IC (DDI). It demonstrates with reference.

3 is a circuit diagram illustrating a driving voltage generator according to an exemplary embodiment of the present invention. As shown in FIG. 3, the driving voltage generator includes a voltage distribution circuit 10 for dividing a first power supply voltage VCI, and a voltage inversion circuit 20 that receives a voltage from the voltage distribution circuit and inverts and outputs the voltage. ) And a voltage boost circuit 30 for boosting and outputting the first power voltage VCI by a voltage corresponding to a difference between the first power voltage VCI and the predetermined second power voltage -Vx. And a comparator 40 for feeding back a boost voltage output from the voltage boost circuit 30 to generate a signal for controlling the voltage boost circuit 30. In particular, in order to achieve the object of the present invention, the second power supply voltage (-Vx) applies a negative voltage.

The voltage distribution circuit 10 includes a plurality of resistors R1 and R2 connected in series, and divides and outputs the first power voltage VCI. The voltage distribution circuit 10 divides the first power voltage VCI and outputs a divided voltage VCI1.

In addition, the voltage inversion circuit 20 receives the divided voltage VCI1 and inverts it to output it. The inversion signal -VCI1 output from the voltage inversion circuit 20 is input to one terminal of the voltage boost circuit 30.

The voltage boost circuit 30 may have a voltage corresponding to a difference between a first power supply voltage VCI applied to an input terminal and a second power supply voltage −Vx input to one terminal, to the first power supply voltage VCI. To increase the output pressure. In a preferred embodiment of the present invention, the inversion signal (-VCI1) output from the voltage inversion circuit 20 is a second power supply voltage (-Vx) input to one terminal of the voltage boost circuit 30.

The boost voltage output through the output terminal of the voltage boost circuit 30 is fed back to the terminal of the comparator 40. The comparator 40 compares the signal obtained by dividing the boost voltage with the divided voltage VCI1 output from the voltage divider circuit 10. As shown in FIG. 3, the boost voltage is divided by two resistors R3 having the same resistance value and input to one terminal of the comparator 40. When the signal obtained by dividing the boost voltage is greater than the divided voltage VCI1, the comparator 40 outputs a signal for stopping the operation of the voltage boost circuit 30.

The voltage boost circuit 30 has one or more capacitors and one or more switch elements, as described above. A first power supply voltage VCI is applied to an input terminal of the voltage boost circuit 30, and a second power supply voltage -Vx is applied through one terminal of the voltage boost circuit 30.

The first power supply voltage VCI is generally a positive voltage. In addition, a negative voltage is applied to the second power voltage (-Vx). In particular, in FIG. 3, the second power voltage (-Vx) is an inverted signal (-) output from the voltage inversion circuit 20. VCI1).

The voltage boost circuit 30 may equally apply the voltage boost circuit shown in FIG. 2. In this case, the boost capacitor C11 stores a voltage VCI + VCI1 corresponding to a difference between the first power voltage VCI and the inversion signal -VCI1. In this case, since the boost voltage is 2VCI + VCI1, when the second power supply voltage (−Vx) is a negative voltage, the boost ratio of the voltage boost circuit 30 may be more than doubled.

In general, in the case of the driving voltage generator to which the feedback method is applied, the efficiency of the output driving voltage may be improved. However, when a voltage drop occurs due to the load current as described above, the driving voltage cannot maintain a constant value. . On the other hand, in the driving voltage generator according to the present invention, the driving voltage can be maintained at a constant value despite the load current, which will be described with reference to FIGS. 4 to 6.

4 is a circuit diagram illustrating a driving voltage generator according to the present invention in consideration of a resistance component. As shown in the drawing, the conductive line, which is generally made of a metal line, has a unique resistance component, and a voltage drop according to the load current is generated by the resistance component.

In the circuit diagram of FIG. 4, the first power supply voltage VCI is 2.8V, and the divided voltage VCI1 divides the first power supply voltage VCI by 0.92 times to have a value of 2.576V. One result is compared with the prior art as shown in Table 1 below. In this case, the resistance component due to the metal line is 8 ohm.

IAVDD The present invention Conventional 0 mA 5.16V 5.16V 1 mA 5.16V 5.138 V 3 mA 5.16V 5.095 V 5 mA 5.16V 4.734 V

Since the voltage boost circuit applied to the conventional driving voltage generator doubles the input voltage, the driving voltage can be kept constant when the load current is small. However, when the load current increases, a voltage drop occurs and the driving voltage decreases.

However, in the case of the voltage boost circuit 30 applied to the driving voltage generator according to the present invention, the high voltage corresponding to VCI + VCI1 is stored in the boost capacitor C11 as described above. In addition, the driving voltage AVDD output through the output terminal according to a feedback scheme maintains 2 * VCI1 values. In this case, the driving voltage AVDD is approximately 5.16V.

When the load current flowing through the resistance component increases, the voltage drop increases. However, since the high voltage corresponding to VCI + VCI1 is stored in the boost capacitor C11 in the present invention, the driving voltage AVDD may be boosted to 2 * VCI1 despite the voltage drop. Therefore, the driving voltage AVDD can be stably maintained at a constant level.

5 is a graph showing the efficiency of the driving voltage output from the driving voltage generator according to the present invention in comparison with the prior art.

In the graph shown in FIG. 5, the horizontal axis is an axis representing a load current, and the vertical axis is an axis representing a generated driving voltage AVDD. L1 in the code | symbol shows the change of the drive voltage according to a load current in the drive voltage generator to which the conventional voltage boost circuit is applied. In particular, L1 represents a case where a feedback structure is not applied.

On the other hand, L2 is a conventional voltage boost circuit, and represents a change in the drive voltage according to the load current in the drive voltage generator having a feedback structure, L3 is a change in the drive voltage according to the load current in the drive voltage generator according to the present invention Indicates.

As shown, in the case of L1, when there is no load current, the voltage booster circuit boosts the power supply voltage to a value corresponding to 2 * VCI1, and the voltage boosted is the driving voltage. In this case, as the load current gradually increases, the driving voltage is lowered without maintaining a constant value.

In the case of L2, the voltage boost circuit doubles the input voltage, indicating that the boost voltage is 2 * VCI. In addition, the driving voltage generated by the feedback structure maintains 2 * VCI1. In this case, since the voltage boosted by the voltage boost circuit is 2 * VCI, the driving voltage can be maintained at 2 * VCI1 for a load current within a predetermined range. However, for the load current outside the predetermined range, the driving voltage is lowered and the efficiency is lowered.

On the other hand, in the driving voltage generator according to the present invention, as shown in L3, the voltage boost circuit boosts the power supply voltage to a value corresponding to 2 * VCI + VCI1. Therefore, as compared with the conventional case, the drive voltage can be maintained at a constant value of 2 * VCI1 for a load current within a sufficient range. When the load current is a large value, the driving voltage generated by the driving voltage generator according to the present invention can prevent the voltage drop by ΔV 1 + ΔV 2 and ΔV 2, respectively, compared to L 1 and L 2.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the present invention as described above, by boosting the power supply voltage by using a negative voltage (negative), it is possible to boost the power supply voltage by a large ratio, so that even if a voltage drop caused by a large load current occurs a constant driving voltage There is an effect that can be generated.

Claims (12)

In a voltage boost circuit for boosting a predetermined power supply voltage and outputting a boost voltage through an output terminal, At least one boost capacitor configured to store a voltage corresponding to a difference between a first power supply voltage applied to an input terminal of the voltage boost circuit and a second power supply voltage applied through one terminal of the voltage boost circuit; And The connection state is controlled such that a voltage is stored in the boost capacitor during the first period, and the connection state is increased such that the boost voltage is output by boosting the first power voltage by a value corresponding to the voltage stored in the boost capacitor during the second period. Having at least one switch element to be controlled, And the second power supply voltage is a negative voltage. The method of claim 1, wherein the first power supply voltage, A voltage boost circuit, characterized in that it is a positive voltage. The method of claim 2, wherein the at least one switch element, First and second switch elements connected in parallel with the first power supply voltage, respectively; A third switch device connected between the second switch device and the second power supply voltage; And And a fourth switch element connected between the first switch element and the output terminal. The method of claim 3, wherein the boost capacitor, And a common node of the first switch element and the fourth switch element, and a common node of the second switch element and the third switch element. The method of claim 4, wherein And an output capacitor connected to the output terminal. A voltage distribution circuit for dividing the first power supply voltage; A voltage inversion circuit that receives a voltage from the voltage distribution circuit and inverts it and outputs the voltage; A voltage boost circuit for boosting and outputting the first power voltage by a voltage corresponding to a difference between the first power voltage and a predetermined second power voltage; And A comparator for comparing a boost voltage fed back from the voltage boost circuit with an output voltage of the voltage distribution circuit to generate a signal for controlling the voltage boost circuit; The second power supply voltage is a driving voltage generator, characterized in that the negative (negative) voltage. The method of claim 6, wherein the voltage boost circuit, At least one boost capacitor configured to store a voltage corresponding to a difference between the first power supply voltage applied to an input terminal of the voltage boost circuit and the second power supply voltage applied through one terminal of the voltage boost circuit; And The connection state is controlled such that a voltage is stored in the boost capacitor during the first period, and the connection state is increased such that the boost voltage is output by boosting the first power voltage by a value corresponding to the voltage stored in the boost capacitor during the second period. And at least one switch element to be controlled. The method of claim 7, wherein the first power supply voltage, A drive voltage generator, characterized in that it is a positive voltage. The method of claim 8, wherein the second power supply voltage, And a negative voltage output from the voltage inversion circuit. The method of claim 9, wherein the at least one switch element, First and second switch elements connected in parallel with the first power supply voltage, respectively; A third switch device connected between the second switch device and the second power supply voltage; And And a fourth switch element connected between the first switch element and the output terminal. The method of claim 10, wherein the boost capacitor, And a common node of the first switch element and the fourth switch element, and a common node of the second switch element and the third switch element. The method of claim 11, And an output capacitor connected to the output terminal.

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