KR20140124109A - Voltage conversion circuit for charge pump - Google Patents

Abstract

Disclosed is a voltage conversion circuit for a charge pump using a physical switching method by electrostatic attraction power between two metal elements. The voltage conversion circuit includes an input terminal which applies a voltage, a pumping circuit which includes a pumping capacitor and a micro electro mechanical system (MEMS) switch to charge and pump the voltage, a clock terminal which transmits a plurality of clocks with a phase difference of 180 degrees in the pumping capacitor of the pumping circuit, and an output terminal which outputs the boosted voltage through the pumping circuit. Thereby, a charge pump circuit with high efficiency is implemented by comprising a high performance switch based on MEMS.

Description

VOLTAGE CONVERSION CIRCUIT FOR CHARGE PUMP [0002]

The present invention relates to a charge pump type voltage conversion circuit that receives and supplies main power to a power source required by a system.

The display driving circuit is equipped with a voltage conversion circuit for converting the inputted direct current to another direct current. The voltage conversion circuit includes a charge pump method using a capacitor, a Buck conversion circuit using an inductor, a boost conversion circuit, or a Buck Boost conversion circuit, and has different advantages and disadvantages. Unlike Buck converter circuit, Boost converter circuit or Buck Boost converter circuit, the charge pump method does not require an inductor. Therefore, the charge pump method can be made relatively small, and the efficiency is high, but the maximum current that can be flowed is relatively small, . When the voltage conversion circuit is fabricated using a silicon-based CMOS to apply the voltage conversion circuit to a display driver circuit, the display device must be assembled with the display panel after the display device fabrication process is completed. . Therefore, in order to apply the charge pump type voltage conversion circuit to the display driver circuit, the switching device is made up of a thin film transistor. However, in the case of a thin film transistor, since a channel layer is formed in an active region to conduct, a voltage drop occurs between a source and a drain when each element is switched, thereby lowering the output efficiency. In order to achieve a high transmission efficiency in a wide frequency band, a low conduction resistance value and a high speed switching of thin film devices should be possible. In the case of a thin film transistor, a conduction resistance due to a channel resistance is considerably large, A leakage current is generated due to the influence of the parasitic capacitor.

One aspect of the present invention provides a charge pump type voltage conversion circuit using a method of physically switching by electrostatic attraction between two metals.

According to an aspect of the present invention, there is provided a voltage conversion circuit comprising: an input terminal for applying a voltage; a pumping circuit including a pumping capacitor and a MEMS switch for charge pumping the voltage; A clock terminal for transmitting a plurality of clocks having a phase difference of 180 degrees; And an output terminal for outputting a voltage boosted through the pumping circuit.

The pumping circuit may include a first pumping capacitor connected to the first MEMS switch and charged with a voltage of the input terminal, the first pumping capacitor including a first MEMS switch receiving a voltage of the input terminal.

The clock terminal may include a first clock signal output terminal for outputting a clock having an amplitude of the same magnitude as the voltage of the input terminal to the first pumping capacitor.

The pumping circuit further includes a second MEMS switch coupled to the first pumping capacitor and a second pumping capacitor coupled to the second MEMS switch to charge a voltage pumped by the first pumping capacitor .

The clock terminal may include a second clock signal output terminal for outputting a clock signal having an amplitude equal to the voltage of the input terminal to the second pumping capacitor.

And an output capacitor that is provided between the pumping circuit and the output terminal and that charges the voltage output from the pumping circuit and outputs the ripple to the output capacitor.

The voltage conversion circuit according to an embodiment of the present invention includes at least one pumping capacitor for charging and storing an applied voltage, a plurality of MEMS switches connected to and switching to the pumping capacitor, And a pumping circuit having a clock terminal for applying a clock for pumping the voltage, wherein the plurality of MEMS switches are capable of switching voltages applied to the plurality of pumping capacitors.

And an output terminal for outputting a voltage that is stored in the pumping capacitor and outputs a voltage to be stepped up, wherein a voltage boosted through the pumping circuit is stored between the output terminal and the pumping circuit, And may further include a capacitor.

Wherein the at least one pumping capacitor comprises a first pumping capacitor and a second pumping capacitor, wherein the plurality of MEMS switches comprises a first MEMS switch, a second MEMS switch and a third MEMS switch, A first clock signal having a phase difference and a second clock signal.

Wherein the first electrode of the first pumping capacitor is connected to the gate of the first MEMS switch and the second electrode of the first pumping capacitor is connected to the source of the first MEMS switch, A drain of the 2MEMS switch, and a gate of the third MEMS switch to form a first node.

The first MEMS switch and the second MEMS switch are respectively controlled to be turned on / off by the first clock signal and the second clock signal, and the third MEMS switch is controlled on / off by the first node .

The first electrode of the second pumping capacitor is connected to the gate of the second MEMS switch and the second electrode of the second pumping capacitor is connected to the source of the second MEMS switch, 3 MEMS switch to form a second node.

And an output capacitor for storing and outputting the pumped voltage, wherein the output capacitor has a first electrode connected to GND and a second electrode connected to the source of the third MEMS switch to form a third node have.

As described above, according to one aspect of the present invention, a circuit of a high-performance switch based on a MEMS can be configured to realize a charge pump type voltage conversion circuit with high efficiency.

1 is a view showing a charge pump type voltage conversion circuit according to an embodiment of the present invention;
Fig. 2 is a view for explaining the operation principle of the MEMS switch included in Fig. 1
3A is a timing chart of a clock signal output from a clock terminal of a charge pump type voltage conversion circuit according to an embodiment of the present invention
FIG. 3B is a diagram schematically showing a voltage value applied to the MEMS switch according to the period of the clock signal of FIG. 3A
4 is a view showing a charge pump type voltage conversion circuit according to another embodiment of the present invention

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals are used to denote like elements in the drawings, even if they are shown in different drawings.

FIG. 1 is a view showing a charge pump type voltage conversion circuit according to an embodiment of the present invention. FIG. 2 is a view illustrating the operation principle of the MEMS switch included in FIG.

The voltage conversion circuit 10 may include a pumping circuit 100, a clock stage 200, an input stage 300 and an output stage 400. In addition, an output capacitor C3 may be provided between the pumping circuit 100 and the output stage 400. [

The pumping circuit 100 may include at least one capacitor and a plurality of MEMS (Micro Electro Mechanical System) switches. 1 illustrates an example in which the pumping circuit 100 of the various embodiments includes two pumping capacitors C1 and C2 and three MEMS switches M1, M2, and M3.

The two pumping capacitors C1 and C2 may include a first pumping capacitor C1 and a second pumping capacitor C2 and three MEMS switches M1, M2, and M3 may include a first MEMS switch M1, A second MEMS switch M2, and a third MEMS switch M3.

The first electrode of the first pumping capacitor Cl is input with the first clock signal CLK1 and may be connected to the gate of the first MEMS switch M1. The second electrode of the first pumping capacitor C1 is connected to the source of the first MEMS switch M1, the drain of the second MEMS switch M2, the gate of the third MEMS switch M3, So that the first node N1 can be configured.

The first electrode of the second pumping capacitor C2 is input with the second clock signal CLK2 and may be connected to the gate of the second MEMS switch M2. The second electrode of the second pumping capacitor C2 may be connected to the source of the second MEMS switch and the drain of the third MEMS switch M3 to configure the second node N2.

The MEMS switches (M1, M2, M3) can be physically contacted and switched by the electrostatic attraction between the two metal electrodes. Referring to FIG. 2, the drain electrodes of the MEMS switches M1, M2 and M3 are pulled toward the gate electrode by the electrostatic force caused by the voltage difference between the gate electrode and the drain electrode, So that the electrode and the source electrode are brought into contact with each other to conduct. At this time, when the voltage difference between the drain electrode and the gate electrode is reduced, the attractive force due to the electrostatic force is reduced and the drain electrode returns to the original state due to the restoring force of the drain electrode. As the voltage increases, the pull in voltage and the lift off voltage can be differently formed depending on the design of the MEMS switches M1, M2, and M3. The path difference between increasing and decreasing voltage is called hysteresis. When this phenomenon is used, the on-state and off- state can be switched.

The clock stage 200 may include a gate of the first MEMS switch M1 and a first clock signal CLK1 output coupled to the first electrode of the first pumping capacitor Cl. The clock stage 200 may include a gate of the second MEMS switch M2 and a second clock signal CLK2 output coupled to the first electrode of the second pumping capacitor C2. The clock signals CLK1 and CLK2 output from the clock stage 200 are 180 degrees out of phase with each other.

The input voltage VDD of the input stage 300 is connected to the drain of the first MEMS switch M1. The output voltage VOUT of the output stage 400 is connected to the source of the third MEMS switch M3 and the output capacitor C3.

The first electrode of the output capacitor C3 is connected to GND and the second electrode of the output capacitor C3 is connected to the source and the output terminal 400 of the third MEMS switch M3 to form a third node N3. The first MEMS switch M1 and the second MEMS switch M2 are turned on / off by the first clock signal CLK1 and the second clock signal CLK2, respectively, and the third MEMS switch M3 is turned on / On / Off is determined by one node.

FIG. 3A is a timing chart of a clock signal output from a clock terminal of a charge pump type voltage conversion circuit according to an embodiment of the present invention. FIG. 3B is a timing chart of a voltage value As shown in FIG.

Referring to FIG. 3A, when the first clock signal is in the Low state (T1 interval), the odd-numbered MEMS switches M1 and M3, the second clock signal CLK2, (T2), the even-numbered MEMS switch M2 is on-state and becomes conductive.

The pumping capacitors C1 and C2 are pumped when each clock signal is in a high state, and the MEMS switches M1, M2 and M3 are common in that they are conducted when each clock signal is Low.

Hereinafter, the operation of the voltage conversion circuit will be described based on the timing chart of FIG. 3A, and the voltage value of each node is shown in the table in FIG. 3B.

The first operation is such that when the first clock signal CLK1 is in a Low state (T1 interval), the first MEMS switch M1 is conductive and the input voltage VDD is transferred to the first node N1, The capacitor C1 is charged with the voltage of VDD. At this time, the second MEMS switch M2 is in the off-state state when the high state (T1) of the second clock signal CLK2 is applied to the gate. Since the voltage of the first node N1 is not transferred to the second node N2, the voltage VDD charged in the first capacitor C1 and the voltage VDD of the first clock signal CLK1 are added And appears as the voltage of the first node N1. Accordingly, the voltage of the first node N1 switches between VDD and 2VDD.

The second operation is the low state (T2) of the second clock signal CLK2, and the second MEMS switch M2 is turned on by the voltage difference between the second clock signal applied to the gate and the drain . At this time, since the first MEMS switch M1 is shut off because the first clock signal CLK1 is in the high state (T2 interval), and the third MEMS switch M3 is driven by the first node N1, It is shut off in the same state as the MEMS switch M1. Therefore, the voltage of the first node N1 is transferred to the second node N2, and the voltage 2VDD is charged to the second capacitor C2. In the second node N2, the voltage charged in the second capacitor C2 and the voltage due to the second clock signal CLK2 are added, thereby switching between 3VDD and 2VDD.

In the third operation, the first and third MEMS switches M1 and M3 are turned on and the second MEMS switch M2 is turned off in the low state interval T1 of the first clock signal CLK1. Here, the first MEMS switch M1 and the third MEMS switch M3 are synchronized to operate by the same clock signal. The voltage of the second node N2 is transferred to the third node N3 by the conductive third MEMS switch M3 and the voltage 3VDD charged to the third capacitor C3 is transferred to the final output terminal VOUT. So that the charge pumping function can be performed. At this time, a voltage pumped by an integral multiple in the final output stage 400 can be obtained.

4 is a diagram showing a charge pump type voltage conversion circuit according to another embodiment of the present invention.

Compared with the voltage conversion circuit shown in Fig. 1, one circuit is added by adding one pair of pumping capacitors C3 and C4 charged by the respective clock signals CLK1 and CLK2. At this time, additional MEMS switches M4 and M5 are required, and the third MEMS switch M3 controls the gate electrode to be two nodes before. In this way, you can continue to add stages to get the desired output value. Hereinafter, the voltage conversion circuit to which one stage is added will be described, and it is needless to say that the embodiment of the present invention also continuously adds the stage with the same principle.

The voltage conversion circuit 10 may include a pumping circuit 100 ', a clock stage 200, an input stage 300, and an output stage 400, as illustrated in FIG. In addition, an output capacitor C3 may be provided between the pumping circuit 100 and the output stage 400. [

The pumping circuit 100 'may include a plurality of pumping capacitors C1, C2, C3 and C4 and a plurality of MEMS switches M1, M2, M3, M4 and M5.

The plurality of pumping capacitors (C1, C2, C3, C4) is a first pumping capacitor (C1). A second pumping capacitor C2, a third pumping capacitor C3, and a fourth pumping capacitor C4. The plurality of MEMS switches M1, M2, M3, M4, and M5 may include a first MEMS switch M1, a second MEMS switch M2, a third MEMS switch M3, a fourth MEMS switch M4, MEMS switch M5.

The first electrode of the first pumping capacitor Cl is input with the first clock signal CLK1 and may be connected to the gate of the first MEMS switch M1. The second electrode of the first pumping capacitor C1 is connected to the source of the first MEMS switch M1, the drain of the second MEMS switch M2, the gate of the third MEMS switch M3, So that the first node N1 can be configured.

The first electrode of the second pumping capacitor C2 is input with the second clock signal CLK2 and may be connected to the gate of the second MEMS switch M2. The second electrode of the second pumping capacitor C2 is connected to the source of the second MEMS switch M2, the drain of the third MEMS switch M3 and the gate of the fourth MEMS switch M4 And configure the second node N2.

The first electrode of the third pumping capacitor C3 receives the first clock signal CLK1. The second electrode of the third pumping capacitor C3 is connected to the source of the third MEMS switch M3, the drain of the fourth MEMS switch M4, and the gate of the fifth MEMS switch M5, N3).

The first electrode of the fourth pumping capacitor C4 receives the second clock signal CLK2. The second electrode of the fourth pumping capacitor C4 may be connected to the source of the fourth MEMS switch M4 and the drain of the fifth MEMS switch M5 to constitute a fourth node N4.

The clock stage 200 is connected to the gate of the first MEMS switch M1 and to the first electrode of the first pumping capacitor C1 and to the first electrode of the third pumping capacitor C3 via a first clock signal CLK1 output . ≪ / RTI > The clock stage 200 includes a gate of the second MEMS switch M2, a first electrode of the second pumping capacitor C2, a second clock signal CLK2 coupled to the first electrode of the fourth pumping capacitor C4, Output stage. The clock signals CLK1 and CLK2 output from the clock stage 200 are 180 degrees out of phase with each other.

The input voltage VDD of the input stage 300 is connected to the drain of the first MEMS switch M1. The output voltage VOUT of the output stage 400 is connected to the source of the fifth MEMS switch M5 and the output capacitor C5.

The first electrode of the output capacitor C5 is connected to GND and the second electrode of the output capacitor C5 may be connected to the source and the output terminal 400 of the fifth MEMS switch M5 to constitute a fifth node N5. The first MEMS switch M1 and the second MEMS switch M2 are turned on / off by the first clock signal CLK1 and the second clock signal CLK2, respectively, and the third MEMS switch M3, 4 MEMS switch M4 and the fifth MEMS switch M5 are turned on / off by the first node N1, the second node N2, and the third node N3, respectively.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be appreciated by those skilled in the art that various other modifications and variations can be made without departing from the spirit and scope of the invention, Are all within the scope of the appended claims.

Claims (13)

An input terminal for applying a voltage;
A pumping circuit including a pumping capacitor and a micro electro mechanical system (MEMS) switch to charge pumping said voltage;
A clock terminal for transmitting a plurality of clocks having a phase difference of 180 degrees to a pumping capacitor of the pumping circuit; And
And an output terminal for outputting a voltage boosted through the pumping circuit. The method according to claim 1,
Wherein the pumping circuit includes a first MEMS switch receiving a voltage at the input terminal and a first pumping capacitor coupled to the first MEMS switch to charge a voltage at the input terminal. 3. The method of claim 2,
And the clock terminal includes a first clock signal output terminal for outputting a clock having an amplitude equal to the voltage of the input terminal to the first pumping capacitor. 3. The method of claim 2,
The pumping circuit further comprising a second MEMS switch coupled to the first pumping capacitor and a second pumping capacitor coupled to the second MEMS switch to charge a voltage pumped by the first pumping capacitor Voltage conversion circuit. 5. The method of claim 4,
And the clock terminal includes a second clock signal output terminal for outputting a clock having an amplitude equal to the voltage of the input terminal to the second pumping capacitor. The method according to claim 1,
And an output capacitor provided between the pumping circuit and the output terminal, the output capacitor charging the voltage output from the pumping circuit and outputting the voltage in a state in which the ripple is removed. A plurality of MEMS (Micro Electro Mechanical System) switches connected to and switching to the pumping capacitors, and a plurality of pumping capacitors connected to the pumping capacitors, the pumping capacitors being connected to the pumping capacitors, And a pumping circuit having an applied clock stage,
Wherein the plurality of MEMS switches switch voltages applied to the plurality of pumping capacitors. 8. The method of claim 7,
And an output terminal for outputting a voltage that is stored in the pumping capacitor and outputs a voltage to be stepped up, wherein a voltage boosted through the pumping circuit is stored between the output terminal and the pumping circuit, Further comprising a capacitor. 8. The method of claim 7,
Wherein the at least one pumping capacitor comprises a first pumping capacitor and a second pumping capacitor, wherein the plurality of MEMS switches comprises a first MEMS switch, a second MEMS switch and a third MEMS switch, A first clock signal having a phase difference, and a second clock signal. 10. The method of claim 9,
Wherein the first electrode of the first pumping capacitor is connected to the gate of the first MEMS switch and the second electrode of the first pumping capacitor is connected to the source of the first MEMS switch, A drain of the 2MEMS switch, and a gate of the third MEMS switch to form a first node. 11. The method of claim 10,
The first MEMS switch and the second MEMS switch are respectively turned on / off by the first clock signal and the second clock signal, and the third MEMS switch is controlled on / off by the first node Voltage conversion circuit 10. The method of claim 9,
The first electrode of the second pumping capacitor is connected to the gate of the second MEMS switch and the second electrode of the second pumping capacitor is connected to the source of the second MEMS switch, 3 MEMS switch to form a second node. 10. The method of claim 9,
Further comprising an output capacitor for storing and outputting the pumped voltage,
The output capacitor having a first electrode connected to GND and a second electrode connected to a source of the third MEMS switch to form a third node.

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