KR20120116136A - Charge pump circuit - Google Patents

Abstract

PURPOSE: A charge pump circuit is provided to reduce circuit driving time and output voltage ripple using a pulse width modulated control signal. CONSTITUTION: A voltage pumping unit(120) generates an output voltage by pumping an input voltage according to a control signal. A control signal generating unit(110) generates the control signal based on the difference between a reference voltage and the output voltage. A pulse width modulated control signal is generated. A pumping section of the voltage pumping unit is varied according to the pulse width modulated control signal.

Description

Charge Pump Circuit {CHARGE PUMP CIRCUIT}

The present invention relates to a charge pump circuit.

Recently, power management technology used in SoC chips is mainly focused on DC-DC power conversion. In addition, a lot of research is being conducted on the battery consumption time and power consumption of portable electronic devices, computer components, and the like that are continuously being developed. Portable electronics, for example, require accurate voltage conversion with high efficiency to power multiple subsystems within the chip with a single battery.

For this voltage conversion, a linear or switch type converter such as a DC-DC converter, a low drop out (LDO) and a charge pump is used. Here, the DC-DC converter is widely used for advantages such as load / line regulation and instant dynamic voltage change, but an external inductor and a large chip area are required to increase the area and cost loss of the PCB mode.

On the other hand, charge pumps do not require a separate inductor and have high stability, which can be very useful when powering subsystems in a chip. Such charge pumps are used in places where relatively high voltages are required, such as DRAM and display driving drivers.

1 shows a conventional charge pump circuit.

As shown in FIG. 1, a conventional charge pump circuit (hereinafter referred to as a “charge pump”) 10 is a switch driven by a first clock CLK1 and a second clock CLK2 having phases opposite to each other. The unit 12 includes an output capacitor 18 and a load 20. The charge pump 10 converts the input DC voltage into an elevated DC voltage as required by the load 20, and the load 20 connected to the output voltage terminal supplies voltage and current from the charge pump 10. Receive. The charge pump 10 may obtain an elevated DC voltage through charging and discharging of a capacitor using a plurality of switches.

That is, the switch unit 12 of the charge pump 10 enumerates the switches using the first clock signal CLK1 and the second clock signal CLK2 which are alternately repeated by the input terminals 14 and 16. By closing it, the charge of the specific node is charged or discharged to the output capacitor 18, and thus, an elevated DC voltage can be obtained.

However, the above-described conventional charge pump 10 has a large ripple of the output voltage and a small range of the load current, and it is difficult to change the output voltage after design. In addition, since the width of the driving clock is always fixed, there is a limit in reducing the output voltage ripple or the circuit driving time.

One embodiment of the present invention is to provide a charge pump circuit that can reduce the output voltage ripple and circuit driving time and effectively increase the output voltage through a pulse width modulated control signal.

As a technical means for achieving the above technical problem, the charge pump circuit according to an embodiment of the present invention is a voltage pumping unit for generating an output voltage by pumping the input voltage according to the control signal and the difference between the reference voltage and the output voltage And a control signal generator for generating a control signal on the basis of the control signal generator, wherein the control signal generator generates a pulse width modulated control signal according to the level of the output voltage, and the pumping section of the voltage pumping part is varied according to the pulse width modulated control signal. .

According to any one of the problem solving means of the present invention described above, it is possible to reduce the output voltage ripple and the circuit driving time and effectively increase the output voltage through the pulse width modulated control signal.

In addition, according to any one of the above-described means for solving the problem of the present invention, when the output voltage is reduced at high load to detect the pulse width modulation, thereby increasing the output voltage to have a wide load range.

1 shows a conventional charge pump circuit.
2 shows a charge pump circuit according to an embodiment of the present invention.
3 illustrates a pulse width modulated control signal of a charge pump according to an embodiment of the present invention.
4 illustrates an operation of a capacitor charged and discharged during a blocking period and a pumping period according to an embodiment of the present invention.
5 illustrates a state of a pulse width modulated control signal at the start of circuit driving and in a steady state according to an embodiment of the present invention.
FIG. 6 illustrates a pulse width modulated control signal from the start of circuit driving until reaching a steady state after a transient response according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

2 shows a charge pump circuit according to an embodiment of the present invention.

As shown in FIG. 2, the charge pump circuit (hereinafter, referred to as “charge pump”) 100 of the present invention includes a control signal generator 110, a voltage pumper 120, a third capacitor 108, and Load 109.

First, each component of the charge pump 100 of the present invention will be described, the voltage pumping unit 120 pumps an input voltage according to a control signal to generate an output voltage. The voltage pumping unit 120 includes a first switch 101, a second switch 102, and a third switch 103. Here, the first switch 101 and the second switch 102 for transmitting the input voltage may be diode coupled PMOS transistors.

In addition, one end of the third switch 103 is connected to the gate of the second switch 102, the other end thereof is connected to the output terminal, and the gate is connected to the connection node of the first capacitor 104 and the first switch 101 described below. It may be a connected PMOS transistor. The third switch 103 is a second capacitor according to the voltage applied to the connection node (hereinafter referred to as “first node”) a 'of the first capacitor 104 and the first switch 101. The voltage applied to the connection node (hereinafter referred to as "second node") b 'between the 105 and the second switch 102 is transmitted as an output voltage.

In addition, the voltage pumping unit 120 is connected to the first capacitor 104 and the second switch 102, one end of which is connected to the first switch 101 and whose charge / discharge is controlled by the output of the inverter 114 to be described later. One end may include a second capacitor 105 which is connected and controlled by the output of the NOR processing unit 113 to be described later.

The voltage pumping unit 120 includes two charge pumps, and the first charge pump includes a first switch 101 and a first capacitor 104, and the second charge pump includes a second switch ( 102 and the second capacitor 105. In addition, the first charge pump and the second charge pump may be in the form including a buffer (106, 107), respectively.

The control signal generator 110 generates a control signal based on the difference between the reference voltage and the output voltage. At this time, the control signal generator 110 generates a control signal pulse-modulated according to the level of the output voltage, the pumping section of the voltage pumping unit 120 is variable according to the pulse-width modulated control signal.

In more detail, as shown in FIG. 2, the control signal generator 110 compares the difference between the reference voltage Vref and the fed back output voltage Vfb and outputs the first signal Vc as a first signal. Comparing unit 111 and a second comparison unit 112 for comparing the difference between the output first signal (Vc) and the ramp signal (Vramp) and outputs the second signal (Vp).

In addition, the control signal generator 110 processes the NOR signal from the output second signal Vp and the clock signal CLK and outputs the NOR processor 113 and the output third signal VOR as a third signal Vnor. An inverter 114 for inverting the Vnor and outputting it as a control signal. At this time, the circuit configuration of the NOR processing unit 113 and the inverter 114 has a very low or high output voltage fed back than the reference voltage so that the difference between the reference voltage and the fed back output voltage becomes the ground voltage or VDD, It is possible to prevent the problem of the circuit operation, in which the comparison of the circuit is not performed normally and the pulse width modulation may not be generated properly.

Next, a description will be given of the operation of the charge pump 100 of the present invention based on the above-described information, when the power is supplied to the circuit of the first charge pump 100, the first switch 101 and the second switch 102 Is closed to flow a current to charge the first capacitor 104 and the second capacitor 105. Here, the first switch 101 and the second switch 102 may have a structure connected by a diode as described above. In this case, when power is supplied to the charge pump 100 circuit, the first switch 101 and the second switch 102 are closed to send a current. It becomes. At this time, the voltages of the first node a 'and the second node b' connecting the control signal generator 110 and the voltage pumping unit 120 represent a DC voltage close to the input voltage VDD. .

Next, when the circuit is driven, the output voltage is close to zero, so the pulse width of the control signal is maximized to increase the output voltage. At this time, the pulse width modulated control signal raises the voltages of the first node a 'and the second node b' by the maximum magnitude of the control signal through the buffers 106 and 107. That is, the voltages of the first node a 'and the second node b' rise by 2VDD and become nodes of the highest voltage. At this time, when the third switch 103 is closed according to the control signal, current flows to the third capacitor 108 and the load 109 of the output terminal, thereby increasing the output voltage.

In addition, as the output voltage rises, the fed back output voltage is transmitted to the control signal generator 110 and a pulse width modulated control signal is generated based on the difference between the reference voltage and the output voltage. At this time, a pulse width modulated control signal is generated according to the level of the output voltage. After that, when the elevated output voltage reaches a steady state, the pulse width of the control signal is fixed.

In this way, the output voltage is not determined by the number of stages of the existing charge pump, but is determined based on the difference between the reference voltage and the fed back output voltage, so that the output voltage can be easily changed. In addition, by detecting the decrease in the output voltage at a high load it can have a wide load range by performing a pulse width modulation. In addition, since the control signal generator 110 and the voltage pumping unit 120 adjust the rise of the output voltage, a separate compensation circuit is not required and more stable operation is possible. Hereinafter, the pulse width modulated control signal of the present invention will be described in more detail with reference to FIG. 3.

3 illustrates a pulse width modulated control signal of a charge pump according to an embodiment of the present invention.

As illustrated in FIG. 3, the first comparator 111 of the control signal generator 110 described above compares the difference between the reference voltage and the output voltage and outputs the first signal 131. The second comparison unit 112 outputs the second signal 133 by comparing the difference between the output first signal 131 and the ramp signal 132.

In addition, the NOR processing unit 113 processes the second signal 133 and the clock signal 134 by NOR signal and outputs the NOR signal as the third signal 135. In this case, the inverter 114 inverts the third signal 135 and transmits the third signal 135 to the voltage pumping unit 120 through the first node a 'as a control signal.

The capacitor is charged and discharged during the blocking period and the pumping period through the pulse width modulated control signal, which will be described in detail with reference to FIG. 4.

4 illustrates an operation of a capacitor charged and discharged during a blocking period and a pumping period according to an embodiment of the present invention.

As shown in FIG. 4A, the charge pump 100 turns off the third switch 103 during the blocking period of the control signal to charge the input voltage to the second capacitor 105. do. In this case, the voltage charged in the third capacitor 108 connected to the third switch 103 may be transferred as an output voltage.

As shown in FIG. 4B, the charge pump 100 turns on the third switch 103 during the pumping period of the control signal to output the voltage charged in the second capacitor 105. Transmit by voltage. Through this process, the output voltage Vout is increased, which will be described in more detail with reference to FIG. 5.

5 illustrates a state of a pulse width modulated control signal at the start of circuit driving and in a steady state according to an embodiment of the present invention.

As shown in FIG. 5A, the output voltage 504 is increased while alternately repeating a blocking period and a pumping period of the pulse width modulated control signal 502. Here, the width of the pumping section has a maximum value MAX, and the width of the blocking section has a minimum value MIN.

As shown in (b) of FIG. 5, when the raised output voltage 504 becomes steady state, the pulse width of the control signal 502 is fixed to a constant width. Here, the width of the blocking section has a maximum value MAX, and the width of the pumping section has a minimum value MIN.

FIG. 6 illustrates a pulse width modulated control signal from the start of circuit driving until reaching a steady state after a transient response according to an embodiment of the present invention.

As shown in (a) and (b) of FIG. 6, the state of the pulse width modulated control signal 502 is changed until the circuit driving initial stage 506, the transient stage 508, and the steady state 510 are reached. It can be seen that. Here, as described above, the blocking period and the pumping period of the pulse width modulated control signal 502 are alternately repeated to increase the output voltage 504.

When the elevated output voltage 504 becomes the steady state 510, it can be seen that the pulse width of the control signal 502 is fixed to a constant width. In this case, the feedback signal output voltage 512 is transmitted to the control signal generator 110, and a pulse width modulated control signal is generated based on the difference between the reference voltage 514 and the feedback output voltage 512.

As such, the output voltage ripple and circuit driving time can be reduced and the output voltage can be effectively increased through the pulse width modulated control signal. In addition, when the output voltage decreases under high load, pulse width modulation is sensed and the output voltage is increased to thereby have a wide load range.

On the other hand, each component shown in Figure 2 may be composed of a kind of 'module'. The term 'module' refers to a hardware component such as software or a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), and the module performs certain roles. However, a module is not limited to software or hardware. A module may be configured to reside on an addressable storage medium and may be configured to execute one or more processors. The functionality provided by the components and modules may be combined into a smaller number of components and modules or further separated into additional components and modules.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

101-103: switch 104: first capacitor
105: second capacitor 106, 107: buffer
108: third capacitor 109: load
110: control signal generator 111: first comparator
112: second comparison unit 113: NOR processing unit
114: inverter 120: voltage pumping unit

Claims (7)

In the charge pump circuit,
A voltage pumping unit for generating an output voltage by pumping an input voltage according to a control signal;
A control signal generator for generating the control signal based on the difference between the reference voltage and the output voltage,
The control signal generator generates a pulse width modulated control signal according to the level of the output voltage,
The pumping section of the voltage pumping unit is variable according to the pulse width modulated control signal.
The method of claim 1,
The control signal generator
A first comparing unit comparing the difference between the reference voltage and the output voltage and outputting the first signal;
A second comparison unit comparing the difference between the output first signal and the ramp signal and outputting the second signal as a second signal;
A NOR processor which processes the output second signal and the clock signal by NOR signal and outputs the result as a third signal;
And an inverter for inverting the output third signal to output the control signal.
The method of claim 2,
The voltage pumping unit
A first switch and a second switch transferring the input voltage;
A first capacitor having one end connected to the first switch and having charge and discharge controlled by an output of the inverter;
A second capacitor having one end connected to the second switch and having charge / discharge controlled by an output of the NOR processor;
And a third switch transferring the voltage applied to the connection node of the second capacitor and the second switch as an output voltage according to the voltage applied to the connection node of the first capacitor and the first switch.
The method of claim 3, wherein
The voltage pumping unit
And the third switch is turned off during the blocking period of the control signal to charge a voltage to the second capacitor.
The method of claim 3, wherein
The voltage pumping unit
And a third switch turned on during the pumping period of the control signal to transfer a voltage charged in the second capacitor as an output voltage.
The method of claim 3, wherein
And the first switch and the second switch are diode coupled PMOS transistors.
The method of claim 3, wherein
And the third switch is a PMOS transistor having one end connected to a gate of the second switch, the other end connected to an output terminal, and a gate connected to a connection node of the first capacitor and the first switch.

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