High-voltage charge pump

Abstract

The utility model discloses a high-voltage charge pump, which comprises a boosting unit, a first capacitor, an anti-backflow unit, a first switch unit and a second switch unit. The boosting unit is connected with a first pole plate of the first capacitor, the second switch unit and power supply voltage; anti-backflow units are arranged between the second pole plate of the first capacitor and the power supply voltage and between the second pole plate of the first capacitor and the output voltage; the first switch unit and the second switch unit are alternately turned on to adjust the first pole plate voltage and the second pole plate voltage of the first capacitor; the first switch unit comprises a bias control unit and a third MOS tube, the bias control unit is used for generating bias voltage based on a second clock signal so as to control the third MOS tube to be turned on, the control end of the third MOS tube is connected with the bias control unit, the first end of the third MOS tube is connected with the power supply voltage, and the second end of the third MOS tube is connected with the first pole plate of the first capacitor. The circuit area is reduced while the driving capability is ensured, and reliable and stable boosting is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of integrated circuits, and in particular relates to a high-voltage charge pump. Background Art

[0002] Figure 1 It is a traditional four-stage Dickson charge pump structure. In the figure, Φ1 and Φ2 are inverted non-overlapping clock signals. The output voltage VOUT can reach 5 times the power supply voltage VIN by gradually raising the voltage. In theory, ignoring the diode voltage drop, a high-voltage output is obtained. The disadvantages of the Dickson charge pump structure are large area, small driving ability, and low reliability.

[0003] Therefore, in view of the above technical problems, it is necessary to provide a new high-voltage charge pump solution.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0005] The utility model aims to provide a high-voltage charge pump, which can realize high-voltage output with a smaller circuit area, thereby solving the problems of large area cost and limited driving capability.

[0006] In order to achieve the above-mentioned object, a specific embodiment of the utility model provides a high-voltage charge pump, wherein the high-voltage charge pump includes a boost unit, a first capacitor, a backflow prevention unit, a first switch unit and a second switch unit;

[0007] The first end of the boost unit is connected to the first plate of the first capacitor and the second switch unit, and the second end of the boost unit is connected to the power supply voltage;

[0008] A backflow prevention unit is provided between the second plate of the first capacitor and the power supply voltage, and a backflow prevention unit is provided between the second plate of the first capacitor and the output voltage;

[0009] The first switch unit is connected to the first plate and the second plate of the first capacitor, and the second switch unit is connected to the first plate of the first capacitor and the reference potential and controls the on-off between the first plate of the first capacitor and the reference potential based on the first clock signal; the first switch unit and the second switch unit are used to be alternately turned on to adjust the first plate voltage of the first capacitor and the second plate voltage of the first capacitor based on the power supply voltage;

[0010] The first switch unit includes a bias control unit and a third MOS tube, the bias control unit is used to generate a bias voltage based on a second clock signal to control the third MOS tube to turn on, the control end of the third MOS tube is connected to the bias control unit, the first end of the third MOS tube is connected to the power supply voltage, and the second end of the third MOS tube is connected to the first plate of the first capacitor.

[0011] In one or more embodiments of the present utility model, the bias control unit includes a control unit and a bias unit;

[0012] The first end of the bias unit is connected to the power supply voltage, and the second end of the bias unit is connected to the control unit and the control end of the third MOS tube;

[0013] The control unit is used to receive a second clock signal to control the on / off connection between the bias unit and the reference potential.

[0014] In one or more embodiments of the present utility model, the control unit includes a first MOS tube and a first current source, the control end of the first MOS tube is used to receive a second clock signal, the first end of the first MOS tube is connected to the first end of the first current source, the second end of the first current source is connected to a reference potential, and the second end of the first MOS tube is connected to a bias unit and the control end of a third MOS tube.

[0015] In one or more embodiments of the present invention, the bias unit includes a first resistor, a first end of the first resistor is connected to the power supply voltage, and a second end of the first resistor is connected to the third MOS tube control end and the control unit.

[0016] In one or more embodiments of the present utility model, the first switch unit also includes a first Zener tube, an anode of the first Zener tube is connected to the control end of the third MOS tube, the second end of the bias unit and the control unit, and a cathode of the first Zener tube is connected to the power supply voltage, the first end of the bias unit and the first end of the third MOS tube.

[0017] In one or more embodiments of the present utility model, the boost unit includes a second Zener tube, an anode of the second Zener tube is connected to the second end of the third MOS tube, the second switch unit and the first plate of the first capacitor, and a cathode of the second Zener tube is connected to the power supply voltage, the backflow prevention unit and the first switch unit.

[0018] In one or more embodiments of the present invention, the third MOS tube is a low-voltage MOS tube.

[0019] In one or more embodiments of the present invention, the second switch unit includes a second MOS tube, a first end of the second MOS tube is connected to a reference potential, a control end of the second MOS tube is used to receive a first clock signal, and a second end of the second MOS tube is connected to a first plate of the first capacitor.

[0020] In one or more embodiments of the present utility model, the backflow prevention unit includes a first diode and a second diode, the first end of the first diode is connected to the power supply voltage, the second end of the first diode is connected to the first end of the second diode and the second plate of the first capacitor, and the second end of the second diode is connected to the output voltage.

[0021] In one or more embodiments of the present invention, the high-voltage charge pump further includes a voltage-stabilizing capacitor, a first plate of the voltage-stabilizing capacitor is connected to the power supply voltage, and a second plate of the voltage-stabilizing capacitor is connected to the output voltage.

[0022] Compared with the prior art, the high-voltage charge pump of the utility model realizes voltage raising through the breakdown voltage of the Zener tube, while protecting other high-side devices from breakdown. The utility model has strong driving capability and small circuit area, and the implementation method is simple and reliable. In addition, the utility model generates the control signal of the high-voltage charge pump switch MOS tube based on the voltage-dividing resistor, which can ensure that the signal voltage difference does not exceed the gate-source withstand voltage of the device, and enables the charge pump to work in a wider power supply voltage range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 The circuit diagram of a high-voltage charge pump in the prior art is shown in FIG.

[0025] Figure 2 4 is a circuit diagram of a high voltage charge pump in one embodiment of the present invention.

[0026] Figure 3 1 is a clock signal waveform diagram of a high voltage charge pump in an embodiment of the present invention.

[0027] Figure 4 1 is a clock signal waveform diagram of a high voltage charge pump in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0030] The term "coupled" or "connected" or "connected" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include connection through other active or passive devices on the basis of achieving the same or similar functional purpose, such as connection through circuits or components such as switches and follower circuits. In addition, in the present utility model, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity or order between these technical features.

[0031] like Figure 2 As shown, a high-voltage charge pump in an embodiment of the present invention includes a boost unit 10 , a first capacitor CF, a backflow prevention unit 20 , a first switch unit 30 and a second switch unit 40 .

[0032] A first end of the boost unit 10 is connected to the first plate A of the first capacitor CF and the second switch unit 40 , and a second end of the boost unit 10 is connected to the power supply voltage VDD.

[0033] In one embodiment, the boost unit 10 includes a second Zener tube Z2, wherein the reverse breakdown voltage VZ2 of the second Zener tube Z2 is about 5.5V. The anode of the second Zener tube Z2 is connected to the second end of the third MOS tube M3, the second switch unit 40, and the first plate A of the first capacitor CF. The cathode of the second Zener tube Z2 is connected to the power supply voltage VDD, the anti-backflow unit 20, and the second end of the third MOS tube M3. It can be understood that the second Zener tube Z2 can clamp the drain-source voltage of the third MOS tube M3 to prevent the transient high voltage coupled from the drain from impacting the MOS tube gate. At the same time, the reverse breakdown voltage VZ2 of the second Zener tube Z2 is used to raise the output voltage VOUT to achieve high-voltage output.

[0034] like Figure 2 As shown, a backflow prevention unit 20 is arranged between the second plate B of the first capacitor CF and the power supply voltage VDD, and a backflow prevention unit 20 is arranged between the second plate B of the first capacitor CF and the output voltage VOUT.

[0035] In one embodiment, the backflow prevention unit 20 includes a first diode D1 and a second diode D2. The first end of the first diode D1 is connected to the power supply voltage VDD, the second end of the first diode D1 is connected to the first end of the second diode D2 and the second plate B of the first capacitor CF, and the second end of the second diode D2 is connected to the output voltage VOUT. The first diode D1 and the second diode D2 can prevent charge backflow and avoid charge waste.

[0036] like Figure 2 As shown, the first switch unit 30 is connected to the first plate A of the first capacitor CF, and the first switch unit 30 is indirectly connected to the second plate B of the first capacitor CF through the first diode D1 of the backflow prevention unit 20. The second switch unit 40 is connected to the first plate A of the first capacitor CF and the reference potential, and the second switch unit 40 controls the on-off between the first plate A of the first capacitor CF and the reference potential based on the first clock signal PH1.

[0037] The first switch unit 30 and the second switch unit 40 are used to be turned on alternately to adjust the voltage of the first plate A of the first capacitor CF and the voltage of the second plate B of the first capacitor CF based on the power supply voltage VDD. In this embodiment, the reference potential may be a ground potential.

[0038] like Figure 2 As shown, the first switch unit 30 includes a bias control unit 31 and a third MOS transistor M3. The bias control unit 31 is used to generate a bias voltage S1 based on the second clock signal PH2 to control the third MOS transistor M3 to turn on, the control end of the third MOS transistor M3 is connected to the bias control unit 31, the first end of the third MOS transistor M3 is connected to the power supply voltage VDD, and the second end of the third MOS transistor M3 is connected to the first plate A of the first capacitor CF and the boost unit 10.

[0039] In one implementation, the bias control unit 31 includes a control unit 311 and a bias unit 312 .

[0040] The first end of the bias unit 312 is connected to the power supply voltage VDD 311, and the second end of the bias unit 312 is connected to the control unit 311. The control unit 311 is used to receive the second clock signal PH2 to control the on-off between the bias unit 312 and the reference potential, and then generate a bias voltage S1 at the second end of the bias unit 312. The bias voltage S1 is used to control the third MOS tube M3 to turn on.

[0041] The control end of the third MOS tube M3 is connected to the control unit 311 and the second end of the bias unit 312 to receive the bias voltage S1, the first end of the third MOS tube M3 is connected to the power supply voltage VDD, and the second end of the third MOS tube M3 is connected to the first plate A of the first capacitor CF. Further, the first end of the MOS tube mentioned in the present application is the source, the second end is the drain, and the control end is the gate.

[0042] In one embodiment, the control unit 311 includes a first MOS transistor M1 and a first current source I REF The control end of the first MOS tube M1 is used to receive the second clock signal PH2, and the first end of the first MOS tube M1 is connected to the first current source I REF The first end of the first current source I REF The second end of the first MOS transistor M1 is connected to the reference potential, and the second end of the first MOS transistor M1 is connected to the second end of the bias unit 312 and the control end of the third MOS transistor M3. REF Used to generate bias current I ref .

[0043] In one embodiment, the bias unit 312 includes a first resistor R1, a first end of the first resistor R1 is connected to the power supply voltage VDD, and a second end of the first resistor R1 is connected to the control end of the third MOS transistor M3 and the second end of the first MOS transistor M1 of the control unit 311. In an optional embodiment, the bias current I ref The product between the voltage and the first resistor R1 is about 5V, so as to ensure that after the first MOS tube M1 is turned on, the potential of the second end of the first resistor R1 is reduced, thereby controlling the third MOS tube M3 to be turned on. Further, in this embodiment, the first MOS tube M1 and the second MOS tube M2 are N-channel MOS tubes, and the third MOS tube M3 is a P-channel MOS tube.

[0044] Further, the first switch unit 30 further includes a first Zener tube Z1. The anode of the first Zener tube Z1 is connected to the control end of the third MOS tube M3, the bias unit 312 and the control unit 311, and the cathode of the first Zener tube Z1 is connected to the power supply voltage VDD, the bias unit 312 and the first end of the third MOS tube M3. It can be understood that the first Zener tube Z1 can clamp the gate-source voltage of the third MOS tube M3, thereby preventing the transient high voltage coupled by the source of the third MOS tube M3 from impacting the gate of the third MOS tube M3.

[0045] The second switch unit 40 includes a second MOS tube M2, a first end of the second MOS tube M2 is connected to the reference potential, a control end of the second MOS tube M2 is used to receive the first clock signal PH1 which is inverted to the second clock signal PH2, and a second end of the second MOS tube M2 is connected to the first plate A of the first capacitor CF.

[0046] In an optional implementation, the high-voltage charge pump further includes a voltage stabilizing capacitor COUT. A first plate of the voltage stabilizing capacitor COUT is connected to the power supply voltage VDD, and a second plate of the voltage stabilizing capacitor COUT is connected to the output voltage VOUT. The voltage stabilizing capacitor COUT is used to smooth voltage fluctuations.

[0047] Furthermore, in this embodiment, the third MOS tube M3 is a low-voltage MOS tube.

[0048] Combine the following Figure 2 , Figure 3 and Figure 4 Explain the principle of the utility model:

[0049] like Figure 3 As shown, the first clock signal PH1 and the second clock signal PH2 are inverted clock signals.

[0050] In the first stage, the first clock signal PH1 is at a high level, and the second clock signal PH2 is at a low level. At this time, the first MOS tube M1 is turned off, thereby turning off the third MOS tube M3, and the second MOS tube M2 is turned on. The power supply voltage VDD charges the second plate B of the first capacitor CF via the first diode D1, and the voltage of the second plate B is clamped to VDD-VD1, where VD1 is the forward conduction voltage drop of the first diode D1. The potential of the first plate A of the first capacitor CF is gradually pulled down until the second Zener tube Z2 breaks down. At this time, the potential of A is clamped to VDD-VZ2, where VZ2 is the reverse breakdown voltage of the second Zener tube Z2. In the first stage, the voltage difference between the second plate B of the first capacitor CF and the first plate A is VZ2-VD1.

[0051] In the second stage, the first clock signal PH1 is at a low level, and the second clock signal PH2 is at a high level. At this time, the second MOS tube M2 is turned off, and the first MOS tube M1 is turned on. By setting the product of the bias current and the resistance value of the first resistor to 5V, the voltage at the second end of the first resistor R1 can be VDD-5V, so the third MOS tube M3 is turned on, and the potential of the first plate A is pulled up to the power supply voltage VDD. Since the voltage difference between the two plates of the first capacitor cannot change suddenly, the voltage difference between the second plate B of the first capacitor CF and the first plate A is still VZ2-VD1, so the potential of B changes to VDD+VZ2-VD1 at this time. Therefore, the high-voltage charge pump proposed in this embodiment generates an output voltage VOUT of VDD+VZ2-VD1-VD2, where VD2 is the forward conduction voltage drop of the second diode D2. In addition, when the voltage of the second plate B of the first capacitor CF changes to VDD+VZ2-VD1, the first diode D1 is in a reverse biased state, and the charge on the first capacitor CF will not flow back into the power supply voltage to cause loss.

[0052] The first stage and the second stage are executed cyclically, so that the output of the high voltage charge pump is stabilized at VDD+VZ2-VD1-VD2. Further, in this embodiment, the first diode D1 and the second diode D2 are set to have the same specifications, so VD1=VD2, that is, VOUT=VDD+VZ2-2VD1.

[0053] like Figure 4 As shown, in an optional implementation, in order to reduce steady-state power consumption, the duty cycle of the first clock signal PH1 and the second clock signal PH2 can be reduced when the output voltage VOUT is high. The first clock signal PH1 and the second clock signal PH2 are still inverted clock signals, and their high-level pulse duty cycle is greater than the low-level pulse duty cycle. When the output voltage VOUT is low, a large duty cycle is maintained to ensure that the output voltage VOUT establishment time is not affected. After detecting that the VOUT voltage is high, the PH1 and PH2 duty cycles can be reduced to reduce power consumption.

[0054] It can be seen from the above technical solutions that the utility model has the following beneficial effects:

[0055] The voltage is raised by the breakdown voltage of the Zener tube, while protecting other high-side devices from breakdown. The utility model has strong driving capability and small circuit area, and the implementation method is simple and reliable. In addition, the utility model generates a control signal of the high-voltage charge pump switch MOS tube based on the voltage divider resistor, which can ensure that the signal voltage difference does not exceed the gate-source withstand voltage of the device, and enables the charge pump to work in a wider power supply voltage range.

[0056] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0057] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high voltage charge pump, characterized in that: The high-voltage charge pump comprises a boost unit, a first capacitor, a backflow prevention unit, a first switch unit and a second switch unit; The first end of the boost unit is connected to the first plate of the first capacitor and the second switch unit, and the second end of the boost unit is connected to the power supply voltage; A backflow prevention unit is provided between the second plate of the first capacitor and the power supply voltage, and a backflow prevention unit is provided between the second plate of the first capacitor and the output voltage; The first switch unit is connected to the first plate and the second plate of the first capacitor, and the second switch unit is connected to the first plate of the first capacitor and the reference potential and controls the connection between the first plate of the first capacitor and the reference potential based on the first clock signal; The first switch unit and the second switch unit are used to be turned on alternately to adjust the first plate voltage of the first capacitor and the second plate voltage of the first capacitor based on the power supply voltage; The first switch unit includes a bias control unit and a third MOS tube, the bias control unit is used to generate a bias voltage based on a second clock signal to control the third MOS tube to turn on, the control end of the third MOS tube is connected to the bias control unit, the first end of the third MOS tube is connected to the power supply voltage, and the second end of the third MOS tube is connected to the first plate of the first capacitor.

2. The high voltage charge pump according to claim 1, characterized in that: The bias control unit comprises a control unit and a bias unit; The first end of the bias unit is connected to the power supply voltage, and the second end of the bias unit is connected to the control unit and the control end of the third MOS tube; The control unit is used to receive a second clock signal to control the on / off connection between the bias unit and the reference potential.

3. The high voltage charge pump according to claim 2, characterized in that: The control unit includes a first MOS tube and a first current source, the control end of the first MOS tube is used to receive a second clock signal, the first end of the first MOS tube is connected to the first end of the first current source, the second end of the first current source is connected to a reference potential, and the second end of the first MOS tube is connected to a bias unit and the control end of a third MOS tube.

4. The high voltage charge pump according to claim 2, characterized in that: The bias unit comprises a first resistor, a first end of the first resistor is connected to a power supply voltage, and a second end of the first resistor is connected to a third MOS tube control end and a control unit.

5. The high voltage charge pump according to claim 1, characterized in that: The first switch unit also includes a first Zener tube, an anode of the first Zener tube is connected to the control end of the third MOS tube and the bias control unit, and a cathode of the first Zener tube is connected to the power supply voltage, the first end of the bias unit and the first end of the third MOS tube.

6. The high voltage charge pump according to claim 1, characterized in that: The boost unit includes a second Zener tube, an anode of the second Zener tube is connected to the second end of the third MOS tube, the second switch unit and the first plate of the first capacitor, and a cathode of the second Zener tube is connected to the power supply voltage, the backflow prevention unit and the first switch unit.

7. The high voltage charge pump according to claim 1, characterized in that: The third MOS tube is a low-voltage MOS tube.

8. The high voltage charge pump according to claim 1, characterized in that: The second switch unit includes a second MOS tube, a first end of the second MOS tube is connected to a reference potential, a control end of the second MOS tube is used to receive a first clock signal, and a second end of the second MOS tube is connected to a first plate of a first capacitor.

9. The high voltage charge pump according to claim 1, characterized in that: The backflow prevention unit includes a first diode and a second diode, wherein the first end of the first diode is connected to the power supply voltage, the second end of the first diode is connected to the first end of the second diode and the second plate of the first capacitor, and the second end of the second diode is connected to the output voltage.

10. The high voltage charge pump according to claim 1, characterized in that: The high-voltage charge pump further includes a voltage-stabilizing capacitor, a first plate of the voltage-stabilizing capacitor is connected to the power supply voltage, and a second plate of the voltage-stabilizing capacitor is connected to the output voltage.

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