Protection circuit for signal transmission switch and protection system for signal transmission switch
By setting a protection unit in the signal transmission switch, the gate-source and gate-drain voltages of the MOS device are protected, solving the problem of shortened device lifespan caused by overvoltage in existing circuits, and improving the reliability and lifespan of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANALOGIX CHINA SEMICON
- Filing Date
- 2023-03-15
- Publication Date
- 2026-06-02
AI Technical Summary
In existing circuits, the highest input voltage is often higher than the device's maximum withstand voltage, which leads to a shortened device lifespan.
The protection circuit employs a signal transmission switch. By setting up a first protection unit and a second protection unit, the gate-source voltage and gate-drain voltage of the MOS device are protected respectively, ensuring that the voltage does not exceed the device's threshold voltage.
It effectively protects MOS devices, prevents shortened lifespan due to overvoltage, and improves device reliability and lifespan.
Smart Images
Figure CN116318096B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of signal transmission switch circuit technology with a wide input voltage range, and more specifically, to a protection circuit and a protection system for a signal transmission switch. Background Technology
[0002] As integrated circuit technology advances, device feature sizes continue to shrink, and device withstand voltages also decrease. However, the voltage range for signal transmission remains unchanged, resulting in input voltages that are typically higher than the device's maximum withstand voltage. This leads to a shortened lifespan for low-voltage devices operating under high-voltage conditions, and consequently, increased costs. Summary of the Invention
[0003] The main objective of this application is to provide a protection circuit and a protection system for a signal transmission switch, so as to at least solve the problem that the maximum input voltage of existing circuits is usually higher than the maximum withstand voltage of the device, which leads to a shortened device life.
[0004] To achieve the above objectives, according to one aspect of this application, a protection circuit for a signal transmission switch is provided. The signal transmission switch includes a first MOS device and a second MOS device. The protection circuit includes: a first protection unit, which includes a first protection module and a second protection module. The first protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the first protection module is used to input a first input voltage signal, the second terminal of the first protection module is used to input a bias voltage signal, and the third terminal of the first protection module is electrically connected to the source of the first MOS device. The first protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The second protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module is used to input the first input voltage signal, the second terminal of the second protection module is used to input the bias voltage signal, and the third terminal of the second protection module is electrically connected to the source of the second MOS device. The second protection module is used to ensure that the gate-source voltage of the second MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The gate-source voltage of the S device is less than the threshold voltage of the second MOS device to protect the second MOS device; the second protection unit includes a third protection module and a fourth protection module. The third protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the third protection module is electrically connected to the drain of the first MOS device. The second terminal of the third protection module is used to input the bias voltage signal. The third terminal of the third protection module is used to output an output voltage signal. The third protection module is used to ensure that the gate-drain voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The fourth protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the fourth protection module is electrically connected to the drain of the second MOS device. The second terminal of the fourth protection module is used to input the bias voltage signal. The third terminal of the fourth protection module is used to output the output voltage signal. The fourth protection module is used to ensure that the gate-drain voltage of the second MOS device is less than the threshold voltage of the second MOS device to protect the second MOS device.
[0005] Optionally, the first protection module includes a third MOS device, which has a source, a gate, and a drain. The source of the third MOS device is used to input the first input voltage signal, the gate of the third MOS device is used to input the bias voltage signal, and the drain of the third MOS device is electrically connected to the source of the first MOS device. The second protection module includes a fourth MOS device, which has a source, a gate, and a drain. The source of the fourth MOS device is used to input the first input voltage signal, the gate of the fourth MOS device is used to input the bias voltage signal, and the drain of the fourth MOS device is electrically connected to the source of the second MOS device. Electrical connection; the third protection module includes a fifth MOS device, which has a source, a gate, and a drain. The drain of the fifth MOS device is electrically connected to the drain of the first MOS device. The gate of the fifth MOS device is used to input the bias voltage signal, and the source of the fifth MOS device is used to output the output voltage signal. The fourth protection module includes a sixth MOS device, which has a source, a gate, and a drain. The drain of the sixth MOS device is electrically connected to the drain of the second MOS device. The gate of the sixth MOS device is used to input the bias voltage signal, and the source of the sixth MOS device is used to output the output voltage signal.
[0006] Optionally, the first MOS device is an NMOS, the second MOS device is a PMOS, the third MOS device is an NMOS, the fourth MOS device is a PMOS, the fifth MOS device is an NMOS, and the sixth MOS device is a PMOS.
[0007] Optionally, the protection circuit further includes: a bias voltage generation circuit having a first terminal, a second terminal, and a third terminal. The first terminal of the bias voltage generation circuit is used to input the first input voltage signal. The second terminal of the bias voltage generation circuit is electrically connected to the second terminal of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module, respectively. The third terminal of the bias voltage generation circuit is used to input a second input voltage signal. The bias voltage generation circuit is used to generate the bias voltage signal.
[0008] Optionally, the bias voltage generation circuit includes: a first voltage divider module having a first terminal and a second terminal, the first terminal of the first voltage divider module being used to input the first input voltage signal; a second voltage divider module having a first terminal and a second terminal, the first terminal of the second voltage divider module being electrically connected to the second terminal of the first voltage divider module, and the second terminal of the second voltage divider module being grounded; a first switch module having a first terminal, a second terminal, a third terminal, and a fourth terminal, the first terminal of the first switch module being electrically connected to the second terminal of the first voltage divider module and the first terminal of the second voltage divider module, the second terminal of the first switch module being used to input the second input voltage signal, and the third terminal of the first switch module being grounded; and a second switch module having a first terminal and a second terminal, the first terminal of the second switch module being electrically connected to the fourth terminal of the first switch module, and the second terminal of the second switch module being electrically connected to the second terminals of the first protection module, the second protection module, the third protection module, and the fourth protection module.
[0009] Optionally, the first switching module includes: a seventh MOS device having a source, a gate, and a drain, wherein the source of the seventh MOS device is electrically connected to the second terminal of the first voltage divider module and the first terminal of the second voltage divider module, and the gate of the seventh MOS device is grounded; an eighth MOS device having a source, a gate, and a drain, wherein the source of the eighth MOS device is electrically connected to the drain of the seventh MOS device, and the gate of the eighth MOS device is used to input the second input voltage signal; and a ninth MOS device having a source, a gate, and a drain, wherein the source of the ninth MOS device is electrically connected to the drain of the eighth MOS device, the gate of the ninth MOS device is grounded, and the drain of the ninth MOS device is electrically connected to the first terminal of the second switching module.
[0010] Optionally, the second switching module includes: a tenth MOS device having a source, a gate, and a drain, the source of the tenth MOS device being electrically connected to the fourth terminal of the first switching module, and the drain of the tenth MOS device being electrically connected to the second terminal of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module; and an eleventh MOS device having a source, a gate, and a drain, the source of the eleventh MOS device being electrically connected to the gate of the tenth MOS device, the gate of the eleventh MOS device being electrically connected to the fourth terminal of the first switching module, and the drain of the eleventh MOS device being electrically connected to the second terminal of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module.
[0011] Optionally, the bias voltage generation circuit further includes: a leakage current protection module having a first terminal, a second terminal, and a third terminal, wherein the first terminal of the leakage current protection module is electrically connected to the second terminal of the second voltage divider module, and the second terminal of the leakage current protection module is grounded, and the leakage current protection module is used to prevent leakage current from being generated in the first voltage divider module and the second voltage divider module under the action of the second input voltage signal; and a third switch module having a first terminal, a second terminal, and a third terminal, wherein the first terminal of the third switch module is electrically connected to the third terminal of the first switch module, the second terminal of the third switch module is electrically connected to the third terminal of the leakage current protection module, and the third terminal of the third switch module is grounded.
[0012] Optionally, the leakage protection module includes a twelfth MOS device, which has a source, a gate, and a drain. The source of the twelfth MOS device is grounded, and the drain of the twelfth MOS device is electrically connected to the second terminal of the second voltage divider module. The third switching module includes a thirteenth MOS device, which has a source, a gate, and a drain. The source of the thirteenth MOS device is grounded, and the drain of the thirteenth MOS device is electrically connected to the gate of the twelfth MOS device. The gate of the thirteenth MOS device is electrically connected to the third terminal of the first switching module.
[0013] According to another aspect of this application, a protection system for a signal transmission switch is provided, comprising a signal transmission switch and a protection circuit for any of the aforementioned signal transmission switches, wherein the signal transmission switch is electrically connected to the protection circuit.
[0014] Applying the technical solution of this application, the protection circuit of the above-mentioned signal transmission switch includes a first MOS device and a second MOS device. The protection circuit includes: a first protection unit, which includes a first protection module and a second protection module. The first protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the first protection module is used to input a first input voltage signal, the second terminal is used to input a bias voltage signal, and the third terminal is electrically connected to the source of the first MOS device. The first protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The second protection module also has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module is used to input the first input voltage signal, the second terminal is used to input a bias voltage signal, and the third terminal is electrically connected to the source of the second MOS device. The second protection module is used to ensure that the gate-source voltage of the second MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The circuit employs two protection units to protect the first MOS device by ensuring that its gate-source voltage is lower than the threshold voltage of the second MOS device. The second protection unit includes a third protection module and a fourth protection module. The third protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the third protection module is electrically connected to the drain of the first MOS device, the second terminal is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. The fourth protection module also has a first terminal, a second terminal, and a third terminal. The first terminal of the fourth protection module is electrically connected to the drain of the second MOS device, the second terminal is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. This circuit, by setting two protection units, prevents the voltage across the signal transmission switch from exceeding its withstand voltage, thereby protecting the switching transistor and solving the problem that the maximum input voltage of existing circuits is often higher than the maximum withstand voltage of the device, leading to a shortened device lifespan. Attached Figure Description
[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0016] Figure 1 A schematic diagram of a signal transmission switch according to an embodiment of this application is shown;
[0017] Figure 2A schematic diagram of the structure of a protection circuit for a signal transmission switch according to an embodiment of this application is shown;
[0018] Figure 3 A schematic diagram of the structure of a protection circuit for another signal transmission switch provided according to an embodiment of this application is shown;
[0019] Figure 4 A schematic diagram of the structure of a protection circuit for another signal transmission switch provided according to an embodiment of this application is shown;
[0020] Figure 5 A schematic diagram of the structure of a protection circuit for another signal transmission switch provided according to an embodiment of this application is shown.
[0021] The above figures include the following reference numerals:
[0022] 10. First protection unit; 11. First protection module; 12. Second protection module; 20. Second protection unit; 21. Third protection module; 22. Fourth protection module; 30. First voltage divider module; 40. Second voltage divider module; 50. Leakage protection module; 60. Third switch module; 100. Signal transmission switch; M1. First MOS device; M2. Second MOS device; M3. Third MOS device; M4. Fourth MOS device; M5. Fifth MOS device;
[0023] M6, the sixth MOS device; M7, the seventh MOS device; M8, the eighth MOS device; M9, the ninth MOS device; M10, the tenth MOS device; M11, the eleventh MOS device; M12, the twelfth MOS device; M13, the thirteenth MOS device. Detailed Implementation
[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all techniques and science used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0028] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.
[0029] As described in the background section, the maximum input voltage of existing circuits is usually higher than the maximum withstand voltage of the device. To address the problem that the maximum input voltage of existing circuits is usually higher than the maximum withstand voltage of the device, which leads to a shortened device lifespan, embodiments of this application provide a protection circuit and a protection system for a signal transmission switch.
[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0031] This embodiment provides a protection circuit for a signal transmission switch.
[0032] like Figure 1 As shown, the previous signal transmission switch was composed of a PMOS device M2 and an NMOS device M1. Under normal circumstances, the maximum withstand voltage of devices M1 and M2 is 1.8V. That is, when M1 is in the closed state, V(G) is 1.65V and when M1 is in the open state, V(G) is 0V. When M2 is in the closed state, V(G) is 1.65V and when M1 is in the open state, V(G) is 3.3V.
[0033] When the signal transmission switch is in the off state, if the input signal range is 0-3.3V, then the following two situations exist:
[0034] The first scenario is when the transmitted signal is equal to 3.3V, i.e., V(In) = 3.3V and V(Out) = 3.3V. In this case, the NMOS device M1 has |Vgs| = 3.3V and |Vgd| = 3.3V. This voltage is greater than the maximum withstand voltage of device M1, which is 1.8V, and will shorten the device's lifespan.
[0035] The second scenario is when the transmitted signal is equal to 0V, i.e., V(in) = 0V and V(out) = 0V. In this case, the PMOS device M2 has |Vgs| = 3.3V and |Vgd| = 3.3V. This voltage is greater than the maximum withstand voltage of device M2, which is 1.8V, and will also shorten the device's lifespan.
[0036] Figure 2 This is a schematic diagram of the protection circuit for a signal transmission switch according to an embodiment of this application. Figure 2 As shown, the signal transmission switch 100 includes a first MOS device M1 and a second MOS device M2. The protection circuit includes a first protection unit 10, which includes a first protection module 11 and a second protection module 12. The first protection module 11 has a first terminal, a second terminal, and a third terminal. The first terminal of the first protection module 11 is used to input a first input voltage signal (i.e., ... Figure 2In the first protection module 11, the second terminal is used to input a bias voltage signal, and the third terminal of the first protection module 11 is electrically connected to the source of the first MOS device M1. The first protection module 11 is used to protect the first MOS device M1 by ensuring that the gate-source voltage of the first MOS device M1 is less than the threshold voltage of the first MOS device M1. The second protection module 12 has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module 12 is used to input the first input voltage signal, the second terminal of the second protection module 12 is used to input the bias voltage signal, and the third terminal of the second protection module 12 is electrically connected to the source of the first MOS device M1. The source of MOS device M2 is electrically connected. The second protection module 12 is used to ensure that the gate-source voltage of the second MOS device M2 is less than the threshold voltage of the second MOS device M2 to protect the second MOS device M2. The second protection unit 20 includes a third protection module 21 and a fourth protection module 22. The third protection module 21 has a first terminal, a second terminal, and a third terminal. The first terminal of the third protection module 21 is electrically connected to the drain of the first MOS device M1. The second terminal of the third protection module 21 is used to input the bias voltage signal, and the third terminal of the third protection module 21 is used to output an output voltage signal (i.e.,...). Figure 2 The third protection module 21 is used to protect the first MOS device M1 by making the gate-drain voltage of the first MOS device M1 less than the threshold voltage of the first MOS device M1. The fourth protection module 22 has a first terminal, a second terminal and a third terminal. The first terminal of the fourth protection module 22 is electrically connected to the drain of the second MOS device M2. The second terminal of the fourth protection module 22 is used to input the bias voltage signal. The third terminal of the fourth protection module 22 is used to output the output voltage signal. The fourth protection module 22 is used to protect the second MOS device M2 by making the gate-drain voltage of the second MOS device M2 less than the threshold voltage of the second MOS device M2.
[0037] Specifically, the first and third protection modules may include multiple NMOS devices connected in series to protect the first MOS device, and the second and fourth protection modules may include multiple PMOS devices connected in series to protect the second MOS device.
[0038] The protection circuit for the signal transmission switch described in this application includes a first MOS device and a second MOS device. The protection circuit comprises: a first protection unit, which includes a first protection module and a second protection module. The first protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the first protection module is used to input a first input voltage signal, the second terminal is used to input a bias voltage signal, and the third terminal is electrically connected to the source of the first MOS device. The first protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The second protection module also has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module is used to input the first input voltage signal, the second terminal is used to input a bias voltage signal, and the third terminal is electrically connected to the source of the second MOS device. The second protection module is used to ensure that the gate-source voltage of the second MOS device is less than the threshold voltage of the first MOS device. The circuit employs two protection units to protect the first MOS device by ensuring that the gate-drain voltage of the first MOS device is less than its threshold voltage. The second protection unit includes a third protection module and a fourth protection module. The third protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the third protection module is electrically connected to the drain of the first MOS device. The second terminal of the third protection module is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. The third protection module is used to ensure that the gate-drain voltage of the first MOS device is less than its threshold voltage. The fourth protection module also has a first terminal, a second terminal, and a third terminal. The first terminal of the fourth protection module is electrically connected to the drain of the second MOS device. The second terminal of the fourth protection module is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. The fourth protection module is used to ensure that the gate-drain voltage of the second MOS device is less than its threshold voltage. This circuit, by setting two protection units, prevents the voltage across the signal transmission switch from exceeding its withstand voltage, thereby protecting the switching transistor and solving the problem that the maximum input voltage of existing circuits is often higher than the maximum withstand voltage of the device, leading to a shortened device lifespan.
[0039] In one alternative embodiment, such as Figure 3As shown, the first protection module 11 includes a third MOS device M3, which has a source, a gate, and a drain. The source of the third MOS device M3 is used to input the first input voltage signal, and the gate of the third MOS device M3 is used to input the bias voltage signal. The drain of the third MOS device M3 is electrically connected to the source of the first MOS device M1. The second protection module 12 includes a fourth MOS device M4, which has a source, a gate, and a drain. The source of the fourth MOS device M4 is used to input the first input voltage signal, and the gate of the fourth MOS device M4 is used to input the bias voltage signal. The drain of the fourth MOS device M4 is electrically connected to the source of the second MOS device M2. Electrical connection; the third protection module 21 includes a fifth MOS device M5, which has a source, a gate, and a drain. The drain of the fifth MOS device M5 is electrically connected to the drain of the first MOS device M1. The gate of the fifth MOS device M5 is used to input the bias voltage signal, and the source of the fifth MOS device M5 is used to output the output voltage signal. The fourth protection module 22 includes a sixth MOS device M6, which has a source, a gate, and a drain. The drain of the sixth MOS device M6 is electrically connected to the drain of the second MOS device M2. The gate of the sixth MOS device M6 is used to input the bias voltage signal, and the source of the sixth MOS device M6 is used to output the output voltage signal.
[0040] Specifically, M4, M6 and M3, M5 provide overvoltage protection, preventing M1 and M2 from being damaged by high voltage. The maximum withstand voltage of devices M1, M3, M5 and M2, M4, M6 is 1.8V. The bias voltage value can be changed according to the different maximum withstand voltages of M1 and M2. Generally, the maximum withstand voltage of M1 and M2 is higher, and the bias voltage value can be reduced accordingly.
[0041] For example, the first MOS device M1 is an NMOS, the second MOS device M2 is a PMOS, the third MOS device M3 is an NMOS, the fourth MOS device M4 is a PMOS, the fifth MOS device M5 is an NMOS, and the sixth MOS device M6 is a PMOS.
[0042] When the signal transmission switch is in the closed state, if the input signal range is 0-3.3V, there are two possibilities:
[0043] In the first scenario, when the transmitted signal is equal to 0V (V(In) = 0V, V(Out) = 0), the gates of NMOS devices M1, M3, and M5 receive a voltage of 1.65V. This means that |Vgs| = 1.65V and |Vgd| = 1.65V for M1, M3, and M5. This voltage is less than the maximum withstand voltage of the NMOS devices (1.8V) and will not shorten the device lifespan. Similarly, the gates of PMOS devices M2, M4, and M6 also receive a voltage of 1.65V. This voltage is also less than the maximum withstand voltage of the PMOS devices (1.8V) and will not shorten the device lifespan.
[0044] In the second scenario, when the transmitted signal equals 3.3V (V(In) = 3.3V, V(Out) = 3.3V), the gate inputs of PMOS devices M2, M4, and M6 are 1.65V, meaning |Vgs| = 1.65V and |Vgd| = 1.65V for M2, M4, and M6. This voltage is less than the maximum withstand voltage of 1.8V for PMOS devices and will not shorten the device lifespan. Simultaneously, for NMOS devices M1, |Vgs| = 0V and |Vgd| = 0V; for M3 and M5, |Vgs| = 1.65V and |Vgd| = 0V. This voltage is also less than the maximum withstand voltage of 1.8V for NMOS devices and will not shorten the device lifespan.
[0045] When the signal transmission switch is in the off state, if the input signal range is 0-3.3V, there are two possibilities:
[0046] In the first scenario, when the transmitted signal is equal to 0V (V(In) = 0V, V(Out) = 0), the voltages of NMOS devices M1 (|Vgs| = 0V and |Vgd| = 0V) and NMOS devices M3 and M5 (|Vgs| = 1.65V and |Vgd| = 1.65V) are both lower than the maximum withstand voltage of 1.8V for NMOS devices, thus not shortening their lifespan. Similarly, the voltages of PMOS devices M4 and M6 (|Vgs| = 1.65V) are also lower than the maximum withstand voltage of 1.8V for PMOS devices, again not shortening their lifespan. Furthermore, devices M4 and M6 are in the off state to prevent PMOS device M2 from seeing a 0V voltage, thereby protecting PMOS device M2.
[0047] In the second scenario, when the transmitted signal equals 3.3V (V(in) = 3.3V, V(out) = 3.3V), the PMOS devices M2 have |Vgs| = 0V and |Vgd| = 0V, while M4 and M6 have |Vgs| = 1.65V and |Vgd| = 1.65V. This voltage is less than the maximum withstand voltage of the PMOS devices (1.8V), so it will not shorten the device lifespan. Similarly, the |Vgs| of M3 and M5 is 1.65V, which is less than the maximum withstand voltage of the NMOS devices (1.8V), also so it will not shorten the device lifespan. Furthermore, devices M3 and M5 are in the off state to prevent the NMOS device M1 from seeing a 0V voltage, thus protecting the NMOS device M1. A bias voltage generation circuit can be used to generate a 1.65V voltage to bias the gate of the MOS transistor.
[0048] As an optional solution, the above protection circuit further includes: a bias voltage generation circuit having a first terminal, a second terminal, and a third terminal. The first terminal of the bias voltage generation circuit is used to input the first input voltage signal. The second terminal of the bias voltage generation circuit is electrically connected to the second terminal of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module, respectively. The third terminal of the bias voltage generation circuit is used to input a second input voltage signal. The bias voltage generation circuit is used to generate the bias voltage signal.
[0049] Specifically, the bias voltage generation circuit is used to generate a bias voltage. It is precisely because the bias voltage biases the gate voltage of each MOS device in the first protection unit and the second protection unit that the first protection unit and the second protection unit can protect the signal transmission switch and prevent the signal transmission switch from being damaged due to overvoltage.
[0050] Furthermore, the bias voltage can simultaneously receive the first input voltage signal and the second input voltage signal. If the second input voltage signal is ineffective, the bias voltage can be generated by the first input voltage signal. In this way, even if the second input voltage signal fails, the bias voltage generation circuit can still generate a bias voltage so that the first protection unit and the second protection unit can provide overvoltage protection for the signal transmission switch.
[0051] In one alternative embodiment, such as Figure 4As shown, the bias voltage generation circuit includes: a first voltage divider module 30, having a first terminal and a second terminal, the first terminal of the first voltage divider module 30 being used to input the first input voltage signal; a second voltage divider module 40, having a first terminal and a second terminal, the first terminal of the second voltage divider module 40 being electrically connected to the second terminal of the first voltage divider module 30, and the second terminal of the second voltage divider module 40 being grounded; a first switch module, having a first terminal, a second terminal, a third terminal, and a fourth terminal, the first terminal of the first switch module being electrically connected to the second terminals of the first voltage divider module 30 and the second voltage divider module 40 respectively, the second terminal of the first switch module being used to input the second input voltage signal (i.e., Vref_se1), and the third terminal of the first switch module being grounded; a second switch module, having a first terminal and a second terminal, the first terminal of the second switch module being electrically connected to the fourth terminal of the first switch module, and the second terminal of the second switch module being electrically connected to the second terminals of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module respectively.
[0052] Specifically, such as Figure 5 As shown, the first voltage divider module can be a resistor R1, and the second voltage divider module can also be a resistor R2. Correspondingly, the first voltage divider module can be multiple resistors connected in series or multiple resistors connected in parallel, and the second voltage divider module can also be multiple resistors connected in series or multiple resistors connected in parallel. The specific circuit structure of the first and second voltage divider modules can be modified according to the actual situation, as long as they can achieve the function of voltage division.
[0053] For example, such as Figure 4 As shown, the first switching module includes: a seventh MOS device M7, having a source, a gate, and a drain, the source of the seventh MOS device M7 being electrically connected to the second terminal of the first voltage divider module 30 and the first terminal of the second voltage divider module 40, and the gate of the seventh MOS device M7 being grounded; an eighth MOS device M8, having a source, a gate, and a drain, the source of the eighth MOS device M8 being electrically connected to the drain of the seventh MOS device M7, and the gate of the eighth MOS device M8 being used to input the second input voltage signal (i.e., Vref_se1); and a ninth MOS device M9, having a source, a gate, and a drain, the source of the ninth MOS device M9 being electrically connected to the drain of the eighth MOS device M8, the gate of the ninth MOS device M9 being grounded, and the drain of the ninth MOS device M9 being electrically connected to the first terminal of the second switching module.
[0054] Specifically, such as Figure 4As shown, the seventh MOS device M7, the eighth MOS device M8, and the ninth MOS device M9 are all PMOS devices. The second input voltage can be set to 3.3V. The gates of the seventh MOS device M7 and the ninth MOS device M9 are also used to input the Vref1 voltage signal (i.e., the voltage divider of the second input voltage). The Vref1 voltage signal is related to the resistance values of R3 and R4. Generally, the resistance values of R3 and R4 are equal, that is, Vref1 is half of the second input voltage. It can also be adjusted according to the actual voltage division situation. The settings of the first switching module can control the magnitude of the bias voltage.
[0055] In another embodiment, such as Figure 3 and Figure 4 As shown, the second switching module includes: a tenth MOS device M10, having a source, a gate, and a drain; the source of the tenth MOS device M10 is electrically connected to the fourth terminal of the first switching module; and the drain of the tenth MOS device M10 is electrically connected to the second terminal of the first protection module 11, the second terminal of the second protection module 12, the second terminal of the third protection module 21, and the second terminal of the fourth protection module 22, respectively. An eleventh MOS device M11, having a source, a gate, and a drain, has its source electrically connected to the gate of the tenth MOS device M10; the gate of the eleventh MOS device M11 is electrically connected to the fourth terminal of the first switching module; and the drain of the eleventh MOS device M11 is electrically connected to the second terminal of the first protection module 11, the second terminal of the second protection module 12, the second terminal of the third protection module 21, and the second terminal of the fourth protection module 22, respectively.
[0056] Specifically, both the tenth and eleventh MOS devices are PMOS.
[0057] The above embodiments can automatically switch the bias voltage between when the chip is not powered on and after power-on to protect the switching circuit.
[0058] When the chip power supply for the second input voltage signal that outputs 3.3V is turned off, that is, when the voltage of the second input voltage signal is 0V, if the first input voltage signal is 3.3V, in order to protect the signal transmission switch and prevent the signal transmission switch from having an overvoltage problem. We can use the first and second voltage divider modules to make the voltage of node vref2 1.5V (or other voltage values, this is just an example). Since the 3.3V power supply voltage of the second input voltage signal is 0V at this time, the voltage of vref1 is equal to 0V. Then the voltage of node Vref3 will be equal to vref2, i.e., 1.5V, due to the conduction of PMOS transistors M7, M8, and M9. Due to the conduction of PMOS transistor M10 (the gate voltage of M10 is V(vref1) = 0), the voltage of node vref_sel is equal to V(vref3) = 1.5V. At this time, the gates of NMOS transistors M3 and PMOS transistor M4 are biased to 1.5V, so that Vgs of these two MOS transistors = V(input terminal) - V(M3, M4 gate) = 3.3V - 1.5V = 1.8V, avoiding the overvoltage problem of M3 and M4.
[0059] When the chip that outputs the second input voltage signal is powered on with a 3.3V power supply, i.e., the voltage of the second input voltage signal is 3.3V, the voltage at node Vref1 will be 1.65V due to the voltage division of the first and second voltage divider modules, i.e., V(vref1) = 1.65V. At this time, PMOS transistor M8 is in the off state after being powered on with 3.3V. At the same time, since the voltage at node vref1 is equal to 1.65V, the thirteenth MOS device (NMOS) is in the on state, which will make the voltage at node V(vref3) equal to 0, thereby turning off the twelfth MOS device (NMOS) to prevent leakage at the signal input terminal through the first voltage divider module, the second voltage divider module, and M12. Furthermore, since V(vref3) = 0, PMOS M11 will be turned on so that V(vref_sel) = V(vref1) = 1.65V. That is, when the input voltage is 3.3V, since the gates (G)vref_sel of M4 and M3 are biased to 1.65V, there will be no overvoltage problem.
[0060] As an alternative solution, such as Figure 4As shown, the bias voltage generation circuit further includes: a leakage current protection module 50, having a first terminal, a second terminal, and a third terminal; the first terminal of the leakage current protection module 50 is electrically connected to the second terminal of the second voltage divider module 40; the second terminal of the leakage current protection module 50 is grounded; the leakage current protection module 50 is used to prevent leakage current from being generated in the first voltage divider module 30 and the second voltage divider module 40 under the action of the second input voltage signal; and a third switch module 60, having a first terminal, a second terminal, and a third terminal; the first terminal of the third switch module 60 is electrically connected to the third terminal of the first switch module; the second terminal of the third switch module 60 is electrically connected to the third terminal of the leakage current protection module 50; and the third terminal of the third switch module 60 is grounded.
[0061] Specifically, the leakage protection module and the third switch module are designed to prevent leakage from the first and second voltage divider modules and avoid affecting the protection circuit when the second input voltage signal is applied.
[0062] For example, such as Figure 4 As shown, the leakage protection module 50 includes a twelfth MOS device M12, which has a source, a gate, and a drain. The source of the twelfth MOS device M12 is grounded, and the drain of the twelfth MOS device M12 is electrically connected to the second terminal of the second voltage divider module 40. The third switching module 60 includes a thirteenth MOS device M13, which has a source, a gate, and a drain. The source of the thirteenth MOS device M13 is grounded, and the drain of the thirteenth MOS device M13 is electrically connected to the gate of the twelfth MOS device M12. The gate of the thirteenth MOS device M13 is electrically connected to the third terminal of the first switching module.
[0063] Specifically, the twelfth and thirteenth MOS devices are both NMOS, while M7, M8, M9, M10, and M11 are all PMOS. Therefore, the source and drain of M7, M8, M9, M10, and M11 can be interchanged.
[0064] Another typical embodiment of this application provides a protection system for a signal transmission switch, including a signal transmission switch and a protection circuit for any of the above-described signal transmission switches, wherein the signal transmission switch is electrically connected to the protection circuit.
[0065] The protection system for the signal transmission switch described in this application includes any of the above-described protection circuits for the signal transmission switch. The signal transmission switch includes a first MOS device and a second MOS device. The protection circuit includes: a first protection unit, which includes a first protection module and a second protection module. The first protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the first protection module is used to input a first input voltage signal, the second terminal of the first protection module is used to input a bias voltage signal, and the third terminal of the first protection module is electrically connected to the source of the first MOS device. The first protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The second protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module is used to input the first input voltage signal, the second terminal of the second protection module is used to input a bias voltage signal, and the third terminal of the second protection module is electrically connected to the source of the second MOS device. The second protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The circuit employs two protection units to protect the first MOS device by ensuring that its gate-source voltage is lower than its threshold voltage. The second protection unit includes a third protection module and a fourth protection module. The third protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the third protection module is electrically connected to the drain of the first MOS device. The second terminal of the third protection module is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. The fourth protection module also has a first terminal, a second terminal, and a third terminal. The first terminal of the fourth protection module is electrically connected to the drain of the second MOS device. The second terminal of the fourth protection module is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. This circuit, by setting two protection units, prevents the voltage across the signal transmission switch from exceeding its withstand voltage, thereby protecting the switching transistor and solving the problem of existing circuits where the maximum input voltage is often higher than the device's maximum withstand voltage, leading to a shortened device lifespan.
[0066] As can be seen from the above description, the embodiments of this application achieve the following technical effects:
[0067] 1) The protection circuit of the signal transmission switch described above in this application includes a first MOS device and a second MOS device. The protection circuit includes: a first protection unit, comprising a first protection module and a second protection module. The first protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the first protection module is used to input a first input voltage signal, the second terminal of the first protection module is used to input a bias voltage signal, and the third terminal of the first protection module is electrically connected to the source of the first MOS device. The first protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The second protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module is used to input the first input voltage signal, the second terminal of the second protection module is used to input a bias voltage signal, and the third terminal of the second protection module is electrically connected to the source of the second MOS device. The second protection module is used to ensure that the gate-source voltage of the second MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The first protection module protects the first MOS device by ensuring that its gate-source voltage is less than its threshold voltage. The second protection unit includes a third protection module and a fourth protection module. The third protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the third protection module is electrically connected to the drain of the first MOS device. The second terminal of the third protection module is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. The third protection module is used to ensure that the gate-drain voltage of the first MOS device is less than its threshold voltage. The fourth protection module also has a first terminal, a second terminal, and a third terminal. The first terminal of the fourth protection module is electrically connected to the drain of the second MOS device. The second terminal of the fourth protection module is used to input a bias voltage signal, and the third terminal is used to output an output voltage signal. The fourth protection module is used to ensure that the gate-drain voltage of the second MOS device is less than its threshold voltage. This circuit, by setting two protection units, prevents the voltage across the signal transmission switch from exceeding its withstand voltage, thereby protecting the switching transistor and solving the problem that the maximum input voltage of existing circuits is usually higher than the maximum withstand voltage of the device, leading to a shortened device lifespan.
[0068] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A protection circuit for a signal transmission switch, characterized in that, The signal transmission switch includes a first MOS device and a second MOS device, and the protection circuit includes: The first protection unit includes a first protection module and a second protection module. A first terminal of the first protection module is used to input a first input voltage signal, a second terminal of the first protection module is used to input a bias voltage signal, and a third terminal of the first protection module is electrically connected to the source of the first MOS device. The first protection module is used to ensure that the gate-source voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The second protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the second protection module is used to input the first input voltage signal, the second terminal of the second protection module is used to input the bias voltage signal, and the third terminal of the second protection module is electrically connected to the source of the second MOS device. The second protection module is used to ensure that the gate-source voltage of the second MOS device is less than the threshold voltage of the second MOS device to protect the second MOS device. The second protection unit includes a third protection module and a fourth protection module. The first terminal of the third protection module is electrically connected to the drain of the first MOS device. The second terminal of the third protection module is used to input the bias voltage signal, and the third terminal of the third protection module is used to output an output voltage signal. The third protection module is used to ensure that the gate-drain voltage of the first MOS device is less than the threshold voltage of the first MOS device to protect the first MOS device. The fourth protection module has a first terminal, a second terminal, and a third terminal. The first terminal of the fourth protection module is electrically connected to the drain of the second MOS device. The second terminal of the fourth protection module is used to input the bias voltage signal, and the third terminal of the fourth protection module is used to output the output voltage signal. The fourth protection module is used to ensure that the gate-drain voltage of the second MOS device is less than the threshold voltage of the second MOS device to protect the second MOS device. A bias voltage generation circuit is provided, wherein a first terminal of the bias voltage generation circuit is used to input the first input voltage signal, a second terminal of the bias voltage generation circuit is electrically connected to the second terminals of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module, respectively, a third terminal of the bias voltage generation circuit is used to input the second input voltage signal, and the bias voltage generation circuit is used to generate the bias voltage signal. The bias voltage generation circuit includes: A first voltage divider module, wherein a first terminal of the first voltage divider module is used to input the first input voltage signal; The second voltage divider module has its first terminal electrically connected to the second terminal of the first voltage divider module, and its second terminal grounded. The first switch module has a first terminal electrically connected to the second terminal of the first voltage divider module and the first terminal of the second voltage divider module, respectively. The second terminal of the first switch module is used to input the second input voltage signal, and the third terminal of the first switch module is grounded. The second switch module has a first terminal electrically connected to the fourth terminal of the first switch module, and a second terminal electrically connected to the second terminals of the first protection module, the second protection module, the third protection module, and the fourth protection module, respectively. A leakage current protection module, wherein the first terminal of the leakage current protection module is electrically connected to the second terminal of the second voltage divider module, the second terminal of the leakage current protection module is grounded, and the leakage current protection module is used to prevent leakage current from the first voltage divider module and the second voltage divider module under the action of the second input voltage signal; The third switch module has a first terminal electrically connected to the third terminal of the first switch module, a second terminal electrically connected to the third terminal of the leakage current protection module, and a third terminal grounded.
2. The protection circuit according to claim 1, characterized in that, The first protection module includes a third MOS device, which has a source, a gate, and a drain. The source of the third MOS device is used to input the first input voltage signal, the gate of the third MOS device is used to input the bias voltage signal, and the drain of the third MOS device is electrically connected to the source of the first MOS device. The second protection module includes a fourth MOS device, which has a source, a gate, and a drain. The source of the fourth MOS device is used to input the first input voltage signal, the gate of the fourth MOS device is used to input the bias voltage signal, and the drain of the fourth MOS device is electrically connected to the source of the second MOS device. The third protection module includes a fifth MOS device, which has a source, a gate, and a drain. The drain of the fifth MOS device is electrically connected to the drain of the first MOS device. The gate of the fifth MOS device is used to input the bias voltage signal, and the source of the fifth MOS device is used to output the output voltage signal. The fourth protection module includes a sixth MOS device, which has a source, a gate, and a drain. The drain of the sixth MOS device is electrically connected to the drain of the second MOS device. The gate of the sixth MOS device is used to input the bias voltage signal, and the source of the sixth MOS device is used to output the output voltage signal.
3. The protection circuit according to claim 2, characterized in that, The first MOS device is an NMOS, the second MOS device is a PMOS, the third MOS device is an NMOS, the fourth MOS device is a PMOS, the fifth MOS device is an NMOS, and the sixth MOS device is a PMOS.
4. The protection circuit according to claim 1, characterized in that, The first switch module includes: The seventh MOS device has a source, a gate, and a drain. The source of the seventh MOS device is electrically connected to the second terminal of the first voltage divider module and the first terminal of the second voltage divider module, respectively. The gate of the seventh MOS device is grounded. The eighth MOS device has a source, a gate, and a drain. The source of the eighth MOS device is electrically connected to the drain of the seventh MOS device, and the gate of the eighth MOS device is used to input the second input voltage signal. The ninth MOS device has a source, a gate, and a drain. The source of the ninth MOS device is electrically connected to the drain of the eighth MOS device. The gate of the ninth MOS device is grounded. The drain of the ninth MOS device is electrically connected to the first terminal of the second switching module.
5. The protection circuit according to claim 1, characterized in that, The second switch module includes: The tenth MOS device has a source, a gate, and a drain. The source of the tenth MOS device is electrically connected to the fourth terminal of the first switching module, and the drain of the tenth MOS device is electrically connected to the second terminal of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module, respectively. The eleventh MOS device has a source, a gate, and a drain. The source of the eleventh MOS device is electrically connected to the gate of the tenth MOS device. The gate of the eleventh MOS device is electrically connected to the fourth terminal of the first switching module. The drain of the eleventh MOS device is electrically connected to the second terminal of the first protection module, the second terminal of the second protection module, the second terminal of the third protection module, and the second terminal of the fourth protection module, respectively.
6. The protection circuit according to claim 1, characterized in that, The leakage protection module includes a twelfth MOS device, which has a source, a gate, and a drain. The source of the twelfth MOS device is grounded, and the drain of the twelfth MOS device is electrically connected to the second terminal of the second voltage divider module. The third switching module includes a thirteenth MOS device, which has a source, a gate, and a drain. The source of the thirteenth MOS device is grounded, and the drain of the thirteenth MOS device is electrically connected to the gate of the twelfth MOS device. The gate of the thirteenth MOS device is electrically connected to the third terminal of the first switching module.
7. A protection system for a signal transmission switch, characterized in that, The system includes a signal transmission switch and a protection circuit for the signal transmission switch as described in any one of claims 1 to 6, wherein the signal transmission switch is electrically connected to the protection circuit.