Positive voltage charge pump reset circuit and radio frequency switch chip

Abstract

This invention relates to the field of wireless communication technology, and provides a positive charge pump reset circuit and an RF switch chip. The circuit includes a low-dropout linear regulator, a positive charge pump, and a first capacitor. The input terminal of the low-dropout linear regulator is connected to a power supply, and its output terminal outputs a power supply voltage to the input terminal of the positive charge pump. The output terminal of the positive charge pump is used to boost the power supply voltage to a preset value to output a positive voltage. The first terminal of the first capacitor is connected to the output terminal of the positive charge pump, and its second terminal is grounded. The positive charge pump reset circuit also includes a reset circuit, whose input terminal is connected to either the input terminal or the output terminal of the positive charge pump. The reset circuit is used to reset the positive charge pump voltage when the received output voltage is greater than the preset value. The positive charge pump reset circuit of this invention has a fast charge reset speed and high reliability.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a positive charge pump reset circuit and a radio frequency switch chip. Background Technology

[0002] In modern integrated circuits, this technology is used for power-off charge discharge in circuits with large capacitive and resistive loads. Specifically, it's applicable to scenarios like RF switches fabricated using Silicon On Insulator (SOI) technology, where high stability of the device state after power-off is crucial. In such circuits, to ensure power supply stability and drive capability during normal chip operation, a positive charge pump (CP) is typically integrated, along with a large-capacity voltage regulator capacitor to store charge, achieving smooth voltage output and suppressing voltage fluctuations.

[0003] However, in practical applications, when the chip power supply rapidly decreases from a high level to a low level (i.e., power-off), the aforementioned circuit structure faces a severe charge discharge problem. Specifically, the large-capacity stabilizing capacitor of the positive charge pump stores a large amount of charge, and the circuit's own high resistive load characteristics obstruct the charge discharge path, preventing the stabilizing capacitor from quickly releasing the stored charge. Consequently, the output voltage of the positive charge pump remains non-zero for an extended period. This residual voltage continuously affects the device's state after power-off, potentially leading to device malfunctions, abnormal initialization upon the next power-on, and even shortened device lifespan, severely restricting the reliability and stability of the circuit system.

[0004] Among related technologies, commonly used methods include employing diode discharge circuit units or gate-source interconnected MOSFET discharge circuit units to achieve charge discharge and reset. The conduction of a diode discharge circuit unit depends on a fixed turn-on voltage (typically around 0.7V). Even under ideal conduction conditions, the potential of the discharged node can only be maintained at a level slightly below this turn-on voltage, failing to reset to zero potential. Similarly, the conduction of a gate-source interconnected MOSFET discharge circuit unit also depends on the threshold voltage between the gate and source, resulting in a residual voltage remaining at the node after discharge. This residual voltage continues to affect the device state, failing to fundamentally solve the problem. Furthermore, taking the diode discharge circuit unit as an example, the PN junction of the diode, under reverse bias or zero bias conditions, generates inherent leakage current due to reverse saturation current, inter-band tunneling effects, etc. With the evolution of process nodes (such as advanced nanometer processes), this leakage current increases significantly, leading to increased static power consumption and violating low-power design requirements. The static leakage characteristics of the gate-source interconnect MOSFET discharge circuit unit are also difficult to control, and this defect is particularly prominent in power-sensitive applications such as RF switches.

[0005] Therefore, there are technical problems with large capacitive load and large resistive load circuits (such as SOI RF switches) after power-off, such as slow charge discharge, residual voltage and additional leakage current in existing discharge schemes. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention proposes a positive charge pump reset circuit to solve the problems of residual voltage and additional leakage current in existing positive charge pump reset circuits.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention provides a positive charge pump reset circuit, which includes a low-dropout linear regulator, a positive charge pump, and a first capacitor. The input terminal of the low-dropout linear regulator is connected to a power supply, and the output terminal of the low-dropout linear regulator outputs a power supply voltage to the input terminal of the positive charge pump. The output terminal of the positive charge pump is used to boost the power supply voltage to a preset value to output a positive voltage. The first terminal of the first capacitor is connected to the output terminal of the positive charge pump, and the second terminal of the first capacitor is grounded. The positive charge pump reset circuit also includes a reset circuit, the input terminal of which is connected to either the input terminal or the output terminal of the positive charge pump. The reset circuit is used to reset the positive charge pump voltage when the received output voltage of the positive charge pump is greater than the preset value and outputs a positive voltage.

[0009] The reset circuit includes a unidirectional conduction circuit unit, a second capacitor, a Schmitt trigger, and a discharge circuit unit;

[0010] The input terminal of the unidirectional conduction circuit unit serves as the input terminal of the reset circuit. The output terminal of the unidirectional conduction circuit unit is connected to the first terminal of the second capacitor and the first input terminal of the Schmitt trigger, respectively. The second terminal of the second capacitor is grounded, and the second input terminal of the Schmitt trigger is connected to the power supply or the supply voltage. The output terminal of the Schmitt trigger is connected to the input terminal of the discharge circuit unit, and the output terminal of the discharge circuit unit is connected to the output terminal of the positive voltage charge pump. The unidirectional conduction circuit unit is used to transfer the preset value output positive voltage to the second capacitor for charging and storage. When the second input terminal of the Schmitt trigger receives the supply voltage, the Schmitt trigger outputs a control signal to control the discharge circuit unit to turn off. When the second input terminal of the Schmitt trigger receives the preset value output positive voltage, the Schmitt trigger outputs the control signal to control the discharge circuit unit to turn on. The discharge circuit unit is used to discharge the charge of the first capacitor to ground, thereby achieving a reset.

[0011] Preferably, the preset value output positive voltage is defined as VPOS, the on-state voltage of the unidirectional conduction circuit unit is defined as Vpn, and the output voltage of the unidirectional conduction circuit unit is defined as VHOLD; satisfying the following relationship:

[0012] VHOLD = VPOS - Vpn.

[0013] Preferably, the unidirectional conduction circuit unit is a diode, with the positive terminal of the diode serving as the input terminal of the unidirectional conduction circuit unit and the negative terminal of the diode serving as the output terminal of the unidirectional conduction circuit unit.

[0014] Preferably, the discharge circuit unit is a MOS transistor, the gate of the MOS transistor serves as the input terminal of the discharge circuit unit, the source of the MOS transistor is grounded, and the drain of the MOS transistor serves as the output terminal of the discharge circuit unit.

[0015] Preferably, the MOS transistor is an NMOS transistor.

[0016] Preferably, within the preset operating range of the discharge circuit unit, the control signal gradually decreases as the operating time increases, triggering the MOS transistor to turn on, thereby increasing the source and drain conductance of the MOS transistor. The preset value output positive voltage and the output voltage of the diode decrease accordingly, causing the power supply and the supply voltage to switch accordingly.

[0017] Secondly, embodiments of the present invention provide a radio frequency switch chip, the radio frequency switch chip including the above-mentioned positive charge pump reset circuit.

[0018] Compared with related technologies, in the embodiments of the present invention, by connecting the input terminal of the reset circuit to the input terminal or the output terminal of the positive charge pump, the reset circuit is used to reset the positive charge pump when the received output voltage of the positive charge pump is greater than a preset value. The output terminal of the unidirectional conduction circuit unit is connected to the first terminal of the second capacitor and the first input terminal of the Schmitt trigger, respectively. The unidirectional conduction circuit unit is used to transfer the preset value output positive voltage to the second capacitor for charging and storage. When the second input terminal of the Schmitt trigger receives the supply voltage, the Schmitt trigger outputs a control signal to control the discharge circuit unit to turn off. When the second input terminal of the Schmitt trigger receives the preset value output positive voltage, the Schmitt trigger outputs a control signal to control the discharge circuit unit to turn on. The discharge circuit unit is used to discharge the charge of the first capacitor to the ground terminal. In this way, without increasing the leakage current in the normal working state, the voltage reset is achieved by the trigger-type discharge circuit unit through the Schmitt trigger. At the same time, the present invention adopts a linear discharge method, which can reset to 0 potential in a short time and realize the fast reset function. Attached Figure Description

[0019] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0020] Figure 1 The circuit diagram of the positive charge pump reset circuit provided in Embodiment 1 of the present invention;

[0021] Figure 2 The waveform diagram is shown for the positive charge pump reset circuit provided in Embodiment 1 of the present invention.

[0022] Figure 3 The circuit diagram is for the positive charge pump reset circuit provided in Embodiment 2 of the present invention.

[0023] Among them, 100 is the positive voltage charge pump reset circuit of Embodiment 1, 1 is the low dropout linear regulator, 2 is the positive voltage charge pump, 3 is the reset circuit, 31 is the discharge circuit unit, and 32 is the unidirectional conduction circuit unit.

[0024] 200. Reset circuit of positive charge pump in Example 2. Detailed Implementation

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Please see Figures 1-2 As shown, this embodiment of the invention provides a positive charge pump reset circuit 100, which includes a low dropout linear regulator (LDO), a positive charge pump 2, and a first capacitor CPOS. The input terminal of the LDO is connected to a power supply VDD, and the output terminal of the LDO outputs a supply voltage VLDO to the input terminal of the positive charge pump 2. The output terminal of the positive charge pump 2 is used to raise the supply voltage VLDO to a preset value to output a positive voltage VPOS. The first terminal of the first capacitor CPOS is connected to the output terminal of the positive charge pump 2, and the second terminal of the first capacitor CPOS is grounded. The positive charge pump reset circuit 100 also includes a reset circuit 3. The input terminal of the reset circuit 3 is connected to the output terminal of the positive charge pump 2, and the reset circuit 3 is used to reset the positive charge pump 2 when the received output voltage of the positive charge pump 2 is greater than the preset value of output positive voltage VPOS. The power supply VDD provides power to the low-dropout linear regulator 1, which outputs a stable supply voltage VLDO to the positive charge pump 2. When the power supply VDD is quickly powered down, the supply voltage VLDO is reset to 0 potential. However, the charge of the preset positive output voltage VPOS can only be discharged from the leakage current of the non-operating positive charge pump 2, causing its voltage to remain high for an extended period. Thus, the positive charge pump 2 raises the supply voltage VLDO to the preset output positive voltage VPOS by a certain factor (e.g., 1 or 2 times), and the reset circuit 3 is used to reset the voltage of the positive charge pump 2.

[0030] The reset circuit 3 includes a unidirectional conduction circuit unit 32, a second capacitor CH, a Schmitt trigger SMT, and a discharge circuit unit 31.

[0031] The input terminal of the unidirectional conduction circuit unit 32 serves as the input terminal of the reset circuit 3. The output terminal of the unidirectional conduction circuit unit 32 is connected to the first terminal of the second capacitor CH and the first input terminal of the Schmitt trigger SMT, respectively. The second terminal of the second capacitor CH is grounded. The second input terminal of the Schmitt trigger SMT is connected to the power supply VDD or the power supply voltage VLDO. The output terminal of the Schmitt trigger SMT is connected to the input terminal of the discharge circuit unit 31, and the output terminal of the discharge circuit unit 31 is connected to the output terminal of the positive charge pump 2. 32 is used to transfer the preset value output positive voltage VPOS to the second capacitor CH for charging and storage. When the second input terminal of the Schmitt trigger SMT receives the supply voltage VLDO, the Schmitt trigger SMT outputs a control signal to control the discharge circuit unit 31 to turn off; when the second input terminal of the Schmitt trigger SMT receives the preset value output positive voltage VPOS, the Schmitt trigger SMT outputs the control signal to control the discharge circuit unit 31 to turn on. The discharge circuit unit 31 is used to discharge the charge of the first capacitor CPOS to ground, thereby achieving a reset. In this way, without increasing the leakage current under normal operating conditions, the voltage reset is achieved by the trigger-type discharge circuit unit 31 through the Schmitt trigger SMT; at the same time, the present invention adopts a linear discharge method, which can reset to 0 potential in a short time, achieving a fast reset function.

[0032] Specifically, when the power supply VDD is powered on and the positive charge pump 2 starts working, the unidirectional conducting circuit unit 32 transmits the preset value output positive voltage VPOS to the second capacitor CH. The Schmitt trigger SMT detects that the power supply VDD or the supply voltage VLDO is high and outputs the control voltage VCL at a low level, which turns off the discharge circuit unit 31. Therefore, no current flows through it and it does not affect the normal operation of the positive charge pump 2.

[0033] When the power supply VDD drops rapidly, the supply voltage VLDO also drops rapidly. The Schmitt trigger SMT detects and outputs the voltage VHOLD, setting the control voltage VCL high and raising the level of the control voltage VCL to match the output voltage VHOLD of the unidirectional conduction circuit unit 32. This also turns on the discharge circuit unit 31, increasing its conductance between the source and drain, allowing the charge of the first capacitor CPOS to be quickly discharged to ground, thus achieving a reset.

[0034] During the process of the preset value output positive voltage VPOS decreasing, since the unidirectional conduction circuit unit 32 is a unidirectional conduction circuit, the output voltage VHOLD of the unidirectional conduction circuit unit 32 will not be forcibly pulled low by the preset value output positive voltage VPOS. Instead, due to the holding effect of the second capacitor CH, the output voltage VHOLD of the unidirectional conduction circuit unit 32 will continue to provide a high level for the control voltage VCL until the charge of the second capacitor CH is discharged to ground by the reverse leakage current of the unidirectional conduction circuit unit 32 and the leakage current of the Schmitt trigger SMT. That is, the output voltage VHOLD of the unidirectional conduction circuit unit 32 will maintain a high voltage for a long time to ensure that the preset value output positive voltage VPOS is reset to 0.

[0035] In this embodiment, the high-level signal during operation is extracted and stored on the first capacitor CPOS. When the power is reset, the charge of the second capacitor CH is used to maintain the opening of the discharge circuit unit 31. Therefore, the high-level signal during operation can come from any node voltage with strong driving capability, including but not limited to VDD / VLDO / VPOS. The detected level should be a voltage that will reset quickly even when the present invention is not used, including the output of a possible power detection circuit.

[0036] In this embodiment, the preset value output positive voltage is defined as VPOS, the conduction voltage of the unidirectional conduction circuit unit 32 is Vpn, and the output voltage of the unidirectional conduction circuit unit 32 is VHOLD; and the following relationship is satisfied:

[0037] VHOLD = VPOS - Vpn.

[0038] In this embodiment, the unidirectional conduction circuit unit 32 is a diode D0. The anode of the diode D0 serves as the input terminal of the unidirectional conduction circuit unit 32, and the cathode of the diode D0 serves as the output terminal of the unidirectional conduction circuit unit 32. During the process of the preset value output positive voltage VPOS decreasing, since the diode D0 is a unidirectional conduction circuit, the output voltage VHOLD of the diode D0 will not be forcibly pulled low by the preset value output positive voltage VPOS. Instead, due to the holding effect of the second capacitor CH, the output voltage VHOLD of the diode D0 will continue to provide a high level for the control voltage VCL until the charge of the second capacitor CH is discharged to ground by the reverse leakage current of the diode D0 and the leakage current of the Schmitt trigger SMT. That is, the output voltage VHOLD of the diode D0 will maintain a high voltage for a long time to ensure that the preset value output positive voltage VPOS is reset to 0.

[0039] In this embodiment, the discharge circuit unit 31 is a MOSFET NM1. The gate of the MOSFET NM1 serves as the input terminal of the discharge circuit unit 31, the source of the MOSFET NM1 is grounded, and the drain of the MOSFET NM1 serves as the output terminal of the discharge circuit unit 31. When VDD or VLDO is detected to be high by a Schmitt trigger (SMT), the output control voltage VCL is low, causing the gate of the MOSFET NM1 to be set to a low level, thus turning off the MOSFET NM1. Since its source-drain conductivity is extremely low, no current flows through it, and it does not affect the normal operation of the positive charge pump 2.

[0040] In this embodiment, the MOS transistor NM1 is an NMOS transistor. The NMOS transistor can be used for signal or power supply switching between circuits in different voltage domains. In digital circuits, a low-level control signal can be used to switch the power supply of a low-voltage control circuit to a high-voltage load; in mixed-signal systems, it isolates the mutual interference between high and low voltage circuits, preventing high-voltage crosstalk from affecting low-voltage sensitive circuits.

[0041] In this embodiment, as Figure 2 As shown, within the preset operating range of the discharge circuit unit 31, the control signal gradually decreases as the operating time increases, triggering the MOSFET NM1 to conduct, thereby increasing the source and drain conductance of the MOSFET NM1. Consequently, the preset value output positive voltage VPOS and the output voltage VHOLD of the diode D0 decrease, causing the voltage at the second input terminal of the Schmitt trigger SMT to switch between the power supply VDD and the power supply voltage VLDO. Specifically, when the discharge circuit unit 31 is in the operating range, the source and drain conductance (conductivity of the source and drain) of the MOSFET NM1 remains constant; while the control voltage VCL and the output voltage VHOLD of the diode D0 are continuously decreasing. The preset value output positive voltage VPOS then drops to 0 and remains there until the end of the operating range, at which point the power supply VDD and the power supply voltage VLDO switch.

[0042] Example 2

[0043] As shown in Figure 3, this embodiment of the invention provides a positive charge pump reset circuit 200, which includes a low-dropout linear regulator 1, a positive charge pump 2, and a first capacitor CPOS. The input terminal of the low-dropout linear regulator 1 is connected to the power supply VDD, and the output terminal of the low-dropout linear regulator 1 outputs a supply voltage VLDO to the input terminal of the positive charge pump 2. The output terminal of the positive charge pump 2 is used to raise the supply voltage VLDO to a preset value to output a positive voltage VPOS. The first terminal of the first capacitor CPOS is connected to the output terminal of the positive charge pump 2, and the second terminal of the first capacitor CPOS is grounded. The positive charge pump reset circuit 200 also includes a reset circuit 3, the input terminal of which is connected to the input terminal of the positive charge pump 2, and the reset circuit 3 is used to reset the voltage of the positive charge pump 2. This second embodiment is similar in principle to the first embodiment, except that the positive terminal of the unidirectional conduction circuit unit 32 is connected from the output terminal of the positive charge pump 2 to the output terminal of the low-dropout linear regulator 1. Clearly, as long as the node voltage minus the voltage drop of the unidirectional conduction circuit can satisfy the operating voltage of the Schmitt trigger (SMT), any node can serve as the source for sampling the output voltage VHOLD of the unidirectional conduction circuit unit 32. This second embodiment produces the same technical effect as the first embodiment, and will not be described further here.

[0044] Example 3

[0045] This invention provides a radio frequency (RF) switch chip, which includes the aforementioned positive charge pump reset circuit (100 / 200). This RF switch chip produces the same technical effects as those in Embodiments 1 and 2, and will not be described further here.

[0046] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A positive voltage charge pump reset circuit, comprising a low-dropout linear regulator, a positive voltage charge pump, and a first capacitor, wherein the input terminal of the low-dropout linear regulator is connected to a power supply, the output terminal of the low-dropout linear regulator outputs a power supply voltage to the input terminal of the positive voltage charge pump, the output terminal of the positive voltage charge pump is used to boost the power supply voltage to a preset value to output a positive voltage, a first terminal of the first capacitor is connected to the output terminal of the positive voltage charge pump, and a second terminal of the first capacitor is grounded; characterized in that, The positive charge pump reset circuit further includes a reset circuit, the input terminal of which is connected to the input terminal or the output terminal of the positive charge pump. The reset circuit is used to reset the voltage of the positive charge pump when the power supply or the power supply voltage is lost. The reset circuit includes a unidirectional conduction circuit unit, a second capacitor, a Schmitt trigger, and a discharge circuit unit; The input terminal of the unidirectional conduction circuit unit serves as the input terminal of the reset circuit. The output terminal of the unidirectional conduction circuit unit is connected to the first terminal of the second capacitor and the first input terminal of the Schmitt trigger, respectively. The second terminal of the second capacitor is grounded, and the second input terminal of the Schmitt trigger is connected to the power supply or the power supply voltage. The output terminal of the Schmitt trigger is connected to the input terminal of the discharge circuit unit, and the output terminal of the discharge circuit unit is connected to the output terminal of the positive voltage charge pump. The unidirectional conduction circuit unit is used to transfer the preset value output positive voltage to the second capacitor for charging and storage. When the Schmitt trigger detects that the power supply or the power supply voltage is high, the Schmitt trigger outputs a low-level control signal, and the discharge circuit unit is turned off. When the Schmitt trigger detects that the power supply or the power supply voltage is low, the Schmitt trigger outputs a high-level control signal, and the discharge circuit unit is turned on. The discharge circuit unit is used to discharge the charge of the first capacitor to ground, thereby achieving a reset.

2. The positive charge pump reset circuit according to claim 1, characterized in that, Define the preset value output positive voltage as VPOS, the conduction voltage of the unidirectional conduction circuit unit as Vpn, and the output voltage of the unidirectional conduction circuit unit as VHOLD; satisfying the following relationship: VHOLD = VPOS - Vpn.

3. The positive charge pump reset circuit according to claim 2, characterized in that, The unidirectional conduction circuit unit is a diode, with the positive terminal of the diode serving as the input terminal and the negative terminal of the diode serving as the output terminal.

4. The positive charge pump reset circuit according to claim 3, characterized in that, The discharge circuit unit is a MOS transistor, with the gate of the MOS transistor serving as the input terminal of the discharge circuit unit, the source of the MOS transistor grounded, and the drain of the MOS transistor serving as the output terminal of the discharge circuit unit.

5. The positive charge pump reset circuit according to claim 4, characterized in that, The MOS transistor is an NMOS transistor.

6. The positive charge pump reset circuit according to claim 4, characterized in that, Within the preset operating range of the discharge circuit unit, the control signal gradually decreases as the operating time increases, triggering the MOS transistor to turn on, thereby increasing the source and drain conductance of the MOS transistor. The preset value output positive voltage and the output voltage of the diode decrease accordingly, causing the power supply and the supply voltage to switch accordingly.

7. A radio frequency switch chip, characterized in that, The radio frequency switch chip includes the positive charge pump reset circuit as described in any one of claims 1-6.

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