Isolation driver and modulation circuit thereof

Abstract

The invention discloses an isolation driver and a modulation circuit thereof, and belongs to the technical field of integrated circuits. The modulation circuit for the isolation driver comprises an oscillation module, a detection feedback module and a switch module, the input end of the oscillation module is connected with an external signal control circuit, and the two output ends of the oscillation module are connected to an external transformer and used for generating sinusoidal signals and outputting the sinusoidal signals to the transformer. The two detection ends of the detection feedback module are connected to the two output ends of the oscillation module in a one-to-one correspondence mode, and the regulation and control end of the detection feedback module is connected to the input end of the oscillation module through the switch module. And the switch of the switch module is adjusted according to the jump state of the common-mode voltage so as to adjust the gain of the oscillation module, so that the oscillation module always keeps oscillation. According to the invention, the oscillation module is always kept oscillating when the voltages on the two sides of the transformer are quickly switched, so that the driving signal is prevented from missing.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to an isolation driver and a modulation circuit thereof. Background Art

[0002] An isolated driver is a chip integrated solution that integrates control signal circuits, isolation barriers, and drive circuits. Figure 1 As shown, it mainly includes: signal control circuit, modulation circuit, transformer, demodulation circuit and power drive circuit. Through the modulation circuit and demodulation circuit, the signal is transmitted on both sides of the transformer, so that the physical electrical isolation between the different voltages on both sides of the transformer can be achieved.

[0003] In the traditional modulation circuit, when the voltage on both sides of the transformer switches quickly, the driving signal will be lost. Therefore, it is urgent to provide a new modulation circuit. Summary of the invention

[0004] The present invention provides an isolation driver and a modulation circuit thereof. The technical solution is as follows:

[0005] In one aspect, a modulation circuit for an isolation driver is provided, comprising: an oscillation module, a detection feedback module, and a switch module;

[0006] The input end of the oscillation module is connected to an external signal control circuit, and the two output ends of the oscillation module are connected to an external transformer for generating a sinusoidal signal to be output to the transformer;

[0007] The two detection ends of the detection feedback module are connected to the two output ends of the oscillation module in a one-to-one correspondence, and the regulation end of the detection feedback module is connected to the input end of the oscillation module through a switch module, which is used to adjust the switch of the switch module according to the jump state of the common mode voltage when a jump occurs in the common mode voltage output by the oscillation module is detected to adjust the gain of the oscillation module so that the oscillation module always keeps oscillating.

[0008] On the other hand, an isolation driver is provided, comprising: a signal control circuit, a modulation circuit for an isolation driver as described above, a transformer, a demodulation circuit and a power driving circuit connected in series in sequence.

[0009] The technical solution provided by the present invention can at least bring the following beneficial effects:

[0010] The original modulation circuit is implemented by an oscillation module. By adding a detection feedback module and a switch module on the basis of the oscillation module, when the voltages on both sides of the transformer switch rapidly, the common-mode voltage of the differential signal output by the oscillation module will jump. The detection feedback module detects whether the common-mode voltage jumps, and when the common-mode voltage jumps, the switch of the switch module is adjusted according to the jump state of the common-mode voltage to adjust the gain of the oscillation module, so that the oscillation module always keeps oscillating. It can be seen that this solution can ensure that the oscillation module always keeps oscillating when the voltages on both sides of the transformer switch rapidly, thereby ensuring that the drive signal will not be lost. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 is a schematic diagram of an isolation driver structure provided by an embodiment of the present invention;

[0013] Figure 2 is a structural diagram of a modulation circuit provided by an embodiment of the present invention;

[0014] Figure 3 This is a circuit diagram of a detection feedback module provided by an embodiment of the present invention;

[0015] Figure 4 is another circuit diagram of a detection feedback module provided by an embodiment of the present invention;

[0016] Figure 5 is a modulation circuit diagram provided by an embodiment of the present invention;

[0017] Figure 6 It is a schematic diagram of current flow in a modulation circuit provided by an embodiment of the present invention;

[0018] Figure 7 is a schematic diagram of current flow in another modulation circuit provided by an embodiment of the present invention;

[0019] Figure 8 This is another modulation circuit diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Please refer to Figure 1 , the isolated driver is used to output the driving signal to drive external power tubes and other devices. In the isolated power application topologies such as half-bridge and full-bridge, due to the high working voltage and fast switching speed of the power tube, the ground potential of the driving end of the isolated driver jumps rapidly. This jump voltage is directly mapped to both ends of the transformer. Due to the coupling capacitor of the transformer, the voltage jump will cause the common-mode current to change, thereby causing the common-mode voltage of Voutp and Voutn input to the transformer by the modulation circuit to jump, which will cause the oscillator to fail, and then cause the drive signal to be missing. Therefore, the isolated driver needs to improve its ability to resist common-mode interference (CMTI).

[0022] Please refer to Figure 2 , a modulation circuit for isolating a driver provided by an embodiment of the present invention comprises: an oscillation module, a detection feedback module and a switch module;

[0023] The input end of the oscillation module is connected to an external signal control circuit, and the two output ends of the oscillation module are connected to an external transformer for generating a sinusoidal signal to be output to the transformer;

[0024] The two detection ends of the detection feedback module are connected to the two output ends of the oscillation module in a one-to-one correspondence, and the regulation end of the detection feedback module is connected to the input end of the oscillation module through a switch module, which is used to adjust the switch of the switch module according to the jump state of the common mode voltage when a jump occurs in the common mode voltage output by the oscillation module is detected to adjust the gain of the oscillation module so that the oscillation module always keeps oscillating.

[0025] In the embodiment of the present invention, the original modulation circuit is implemented by an oscillation module. By adding a detection feedback module and a switch module on the basis of the oscillation module, when the voltages on both sides of the transformer are rapidly switched, the common-mode voltage will jump. The detection feedback module detects whether the common-mode voltage jumps, and when the common-mode voltage jumps, the switch of the switch module is adjusted according to the jump state of the common-mode voltage to adjust the gain of the oscillation module, so that the oscillation module always keeps oscillating. It can be seen that this solution can ensure that the oscillation module always keeps oscillating when the voltages on both sides of the transformer are rapidly switched, thereby ensuring that the drive signal will not be lost.

[0026] The detection feedback module in the embodiment of the present invention may include at least two types. The two types of detection feedback modules are described below respectively.

[0027] Please refer to Figure 3 , which is a first type of detection feedback module, the detection feedback module includes a PMOS tube M9, a PMOS tube M10, an NMOS tube M11, a capacitor C2 and a first control unit One Shot;

[0028] The gate of the PMOS tube M9 and the gate of the PMOS tube M10 are two detection terminals of the detection feedback module;

[0029] The source of the PMOS tube M9 is connected to the source of the PMOS tube M10, and both are connected to the power supply voltage;

[0030] The drain of the PMOS tube M9 is connected to the drain of the PMOS tube M10, and the connection point is connected to the drain of the NMOS tube M11;

[0031] The drain of the NMOS tube M11 is also connected to the positive electrode of the capacitor C2, and the connection point is connected to the input end of the first control unit OneShot, and the output end of the first control unit One Shot serves as the control end;

[0032] The source of the NMOS tube M11 is connected to the negative electrode of the capacitor C2, and the connection point is grounded.

[0033] In this type of detection feedback module, three transistors constitute the main structure of the detection feedback module. Figure 3 Among them, the three transistors M9 and M10 are PMOS tubes, and the transistor M11 is NMOS tube; the transistor M11 can also be a PMOS tube and placed between the crystals M9 and M10 and the power supply. Under normal working conditions, because the Voutp and Voutn output by the oscillation module are differential signals, the output Vo of the detection feedback module remains high; when the common mode voltage jumps due to the rapid jump of the voltage at both ends of the transformer, the oscillation signal may be missing, and the current generated by the PMOS tube M9 and the PMOS tube M10 cannot meet the extraction current requirement of the NMOS tube M11. The NMOS tube will extract charge from the capacitor C2, causing the output Vo to become low. The signal is processed by the subsequent monostable circuit to generate a pulse signal, and the pulse signal is used to feedback control the oscillation module, thereby adjusting the gain of the oscillation module, so that the oscillation module always maintains oscillation.

[0034] Please refer to Figure 4 , is a second type of detection feedback module, which includes PMOS tubes M12-15, NMOS tubes M16-M22 and a second control unit One Shot;

[0035] The source of the PMOS tube M12, the source of the PMOS tube M13, the source of the PMOS tube M14 and the source of the PMOS tube M15 are connected and are all connected to the power supply voltage;

[0036] The gate of the PMOS tube M12 is connected to the gate of the PMOS tube M13, and the drain of the PMOS tube M13 is connected to the gate of the PMOS tube M13, the drain of the PMOS tube M14, the drain of the NMOS tube M16, and the drain of the NMOS tube M18;

[0037] The drain of the PMOS tube M12 is connected to the drain of the NMOS tube M20, and the connection point is connected to the second control unit OneShot, and the output end of the second control unit One Shot serves as the control end;

[0038] The gate of the PMOS tube M14 is connected to the gate of the PMOS tube M15, and the drain of the PMOS tube M15 is connected to the gate of the PMOS tube M15, the drain of the NMOS tube M19, and the drain of the NMOS tube M17;

[0039] The gate of the NMOS tube M16 is connected to the gate of the NMOS tube M19, and the connection point is a detection terminal;

[0040] The gate of the NMOS tube M17 is connected to the gate of the NMOS tube M18, and the connection point is another detection terminal;

[0041] The source of the NMOS tube M16 is connected to the source of the NMOS tube M17, and the connection point is connected to the drain of the NMOS tube M21;

[0042] The source of the NMOS tube M18 is connected to the source of the NMOS tube M19, and the connection point is connected to the drain of the NMOS tube M22;

[0043] The gate of the NMOS tube M20, the gate of the NMOS tube M21, and the gate of the NMOS tube M22 are all connected to the power supply VB; the source of the NMOS tube M20, the source of the NMOS tube M21, and the source of the NMOS tube M22 are all grounded.

[0044] In this type of detection feedback module, NMOS tubes M21 and M22 provide bias current for NMOS tubes M16, M17, M18 and M19, and the ratio of differential pair tubes M16 and M17, and the ratio of differential pair tubes M18 and M19 are both 1:N, where N is a positive integer greater than 1, that is, M17 and M19 are both formed by N NMOS tubes connected in parallel. It should be noted that the differential pair tubes can also be PMOS differential pair tubes, and only the current bias and load position need to be modified.

[0045] PMOS tube M15 and PMOS tube M14 are used as loads, and their ratio is 1:(N-1). In the normal bias state, since the ratio of M15 to M14 is smaller than the ratio of the differential pair tubes M16 and M17, M13 needs to provide additional current to ensure balance. Among them, the current flowing through M13 is approximately:

[0046]

[0047] The meaning of each parameter in the formula is: n C ox is the intrinsic parameter of NMOS tube, W / L is the width-to-length ratio of a single NMOS, V GS is a DC voltage signal, Vth is the threshold voltage of the NMOS tube, Δv GS It is an AC voltage signal.

[0048] M13 and M12 are in a mirror relationship, and M20 serves as the load of M12. It can be seen that the output Vo is determined by the size of M12 and M20. If the overcurrent of M12 is greater than that of M20, the output is high, otherwise the output is low.

[0049] In one embodiment of the present invention, please refer to Figure 3 and Figure 4 The detection feedback module may further include: a bias module for providing a bias current so that the detection feedback module is biased within a specified range and the differential signal output by the oscillation module can be detected. It should be noted that if the output of the oscillation module can be reasonably set so that the common mode voltage of Voutp and Voutn is at a suitable value, the bias circuit may not be included in the detection feedback module.

[0050] In one embodiment of the present invention, the oscillation module is an LC oscillator or a ring oscillator.

[0051] The above two types of detection feedback modules are both applicable to LC oscillators and ring oscillators.

[0052] The modulation circuit is described below by taking the oscillation module as an LC oscillator and the first type of detection feedback module as an example.

[0053] Please refer to Figure 5 When the oscillation module is an LC oscillator, the switch module includes: an NMOS tube M8; the gate of the NMOS tube M8 is connected to the regulating end, the source of the NMOS tube M8 is grounded, and the NMOS tube M8 is connected in parallel with the regulating resistor R1 of the LC oscillator.

[0054] Figure 5 In the embodiment, the LC oscillator includes a first cross-coupled pair of tubes and a second cross-coupled pair of tubes connected in parallel, the first cross-coupled pair of tubes is connected to R1, and the second cross-coupled pair of tubes is connected to a power supply; wherein, M0, M1, M2, M3, M4, M5, M6, M7, L1, C0, C1 and R1 constitute an LC oscillator structure, the first cross-coupled pair of tubes includes M0 and M1, and the second cross-coupled pair of tubes includes M2 and M3; M9, M10, M11 and C2 constitute a detection feedback circuit for feedback control, and M8 is a switch module. In a normal state, PMOS tube M2, PMOS tube M3, NMOS tube M0, and NMOS tube M1 participate in the work, and Voutp and Voutn are output as differential sinusoidal signals. The working current of the oscillation module and the common mode voltage of the output differential signal are adjusted by resistor R1, so that PMOS tube M9 and PMOS tube M10 work normally, the output Vo is high level, and NMOS tube M8 is turned off. It should be noted that the role of the resistor R1 is to determine the bias current of the LC oscillator. By adjusting the resistor R1, the common mode voltage of the differential signal is adjusted to ensure the normal operation of M9 and M10. If the common mode voltage output after adjustment cannot ensure the normal operation of the PMOS tubes M9 and M10, an additional bias module needs to be added. The bias module is as follows: Figure 3 As shown. When the voltage jumps from low to high on the demodulation circuit side, the jump voltage will inject current into the oscillation module through the parasitic capacitance of the transformer, causing the common-mode voltage of Voutp and Voutn to increase. Due to the body diode of the PMOS tube, the maximum voltage will be clamped at VCC+0.7V, and the common-mode voltage is determined to be pulled up to the first clamping voltage. At this time, the PMOS tubes M2 and M3, M9 and M10 will be abnormally turned off. The presence of the tail current tube M11 makes the output Vo low, generating a pulse signal to turn on the NMOS tube M8. The circuit maintains normal oscillation through M0, M1 and M8. Please refer to the current flow direction. Figure 6. When the voltage jumps from high to low on the demodulation circuit side, the jump voltage will draw current to the oscillation module through the parasitic capacitance of the transformer, causing the common-mode voltage of Voutp and Voutn to be pulled down. Due to the body diode of the NMOS tube, the maximum voltage will be clamped at VSS-0.7V, and the common-mode voltage is determined to be pulled down to the second clamping voltage. At this time, the NMOS tube M0 and NMOS tube M1 will be abnormally turned off, and the output Vo will maintain a high output unchanged, and the output of the first control unit will not be triggered. The NMOS tube M8 remains closed, and the oscillation is maintained through M4, M2 and M3. Please refer to the current flow direction. Figure 7 .

[0055] That is to say, when a voltage jump from low to high occurs on the demodulation circuit side, the jump voltage injects current into the oscillation module through the transformer so that the common-mode voltage is pulled up. When the common-mode voltage is pulled up to the first clamping voltage, the input end of the first control unit One Shot changes from a high level to a low level, triggering the output end of the first control unit to output a pulse signal, turning on the NMOS tube M8 and maintaining an on time, so as to continue to maintain oscillation through the NMOS tube M8 and the first cross-coupling pair of tubes; it should be noted that after M8 is turned on and maintained for a period of time, when the common-mode voltage is stable, M8 is automatically turned off to ensure low power consumption under normal working conditions.

[0056] When the voltage jumps from high to low on the demodulation circuit side, the jump voltage draws current from the oscillation module through the transformer, so that the common-mode voltage is pulled down. When the common-mode voltage is pulled down to the second clamping voltage, the input end of the first control unit OneShot maintains a high level, and the output of the first control unit is not triggered. The NMOS tube M8 remains turned off, and the oscillation module switches the second cross-coupling pair of tubes to maintain oscillation.

[0057] It should be noted that the connection relationship of the above LC oscillator is only one example, and other examples may also be included. For example, Figure 5 In the figure, M4 is replaced by a current source for power supply side control. For example, the current source is realized by a resistor R, and a PMOS tube is also required to be connected in parallel with the resistor R. The PMOS tube connected in parallel with the resistor R is a switch module, which is used to realize that when the voltage jumps from high to low on the demodulation circuit side, the PMOS tube is used as a switch module to realize that M2 and M3 jointly maintain oscillation.

[0058] The modulation circuit is described below by taking the oscillation module as a ring oscillator and the second type of detection feedback module as an example.

[0059] Please refer to Figure 8 , when the oscillation module is a ring oscillator, the switch module includes: a PMOS tube M32, a PMOS tube M32, an NMOS tube M54 and an NMOS tube M56;

[0060] The ring oscillator comprises a ring oscillator body circuit, a first-stage driving circuit and a second-stage driving circuit;

[0061] The second-stage driving circuit includes two driving sub-circuits corresponding to the two differential signals one by one; the first driving sub-circuit includes a PMOS tube M29, a PMOS tube M38, an NMOS tube M45 and an NMOS tube M53; the second driving sub-circuit includes a PMOS tube M31, a PMOS tube M39, an NMOS tube M45 and an NMOS tube M55;

[0062] The sources of the PMOS tubes M29 to M32 are all connected, and the sources of the NMOS tubes M53 to M56 are all connected;

[0063] The drain of the PMOS tube M29 is connected to the drain of the PMOS tube M30, and both are connected to the source of the PMOS tube M38; the drain of the PMOS tube M38 is connected to the drain of the NMOS tube M45; the gate of the PMOS tube M38 is connected to the gate of the NMOS tube M45;

[0064] The drain of the NMOS tube M53 is connected to the drain of the NMOS tube M54, and both are connected to the source of the NMOS tube M45;

[0065] The drain of the PMOS tube M31 is connected to the drain of the PMOS tube M32, and both are connected to the source of the PMOS tube M39; the drain of the PMOS tube M39 is connected to the drain of the NMOS tube M46; the gate of the PMOS tube M39 is connected to the gate of the NMOS tube M46;

[0066] The drain of the NMOS tube M55 is connected to the drain of the NMOS tube M56, and both are connected to the source of the NMOS tube M46;

[0067] The regulating end includes a first regulating end INn and a second regulating end INp;

[0068] The gate of the PMOS tube M30 and the gate of the PMOS tube M32 are both connected to the first regulating terminal INp;

[0069] The gate of the NMOS transistor M54 and the gate of the NMOS transistor M56 are both connected to the second regulating terminal INn.

[0070] Figure 8 Among them, M24~M26, M33~M35, M40~M42, M48~M50 are the main circuit of the ring oscillator; the first-stage driving circuit also includes two driving sub-circuits, one is composed of M27, M36, M43 and M51, and the other is composed of M28, M37, M44 and M52.

[0071] In the embodiment of the present invention, Figure 8 The implementation principle of the detection feedback module is:

[0072] When the voltage jumps from low to high on the demodulation circuit side, the jump voltage will inject current into the oscillation module through the parasitic capacitance of the transformer, so that the common mode voltage of Voutp and Voutn is pulled up, and the differential signal amplitude becomes weaker. After being processed by the differential pair tubes M16 to M19, the current flowing through the PMOS tube M13 becomes smaller. The existence of the tail current tube M20 makes the output Vo lower, and a pulse signal is generated to turn on the NMOS tubes M54 and M56. The circuit drives the output normally through M45, M46, M54 and M56;

[0073] When the voltage jumps from high to low on the demodulation circuit side, the jump voltage will draw current to the oscillation module through the parasitic capacitance of the transformer, so that the common mode voltage of Voutp and Voutn is pulled down, and the differential signal amplitude becomes weaker. After being processed by the differential pair tubes M16 to M19, the current flowing through the PMOS tube M13 becomes smaller. The presence of the tail current tube M20 makes the output Vo lower, and a pulse signal is generated to turn on the PMOS tubes M30 and M32, and the normal drive output is maintained through M30, M38, M32 and M39.

[0074] On the other hand, an embodiment of the present invention further provides an isolation driver, comprising: a signal control circuit connected in series in sequence, a modulation circuit for an isolation driver as described in any of the above embodiments, a transformer, a demodulation circuit and a power drive circuit.

[0075] It should be noted that, in this article, relational terms such as first, second, third and fourth are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0076] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A modulation circuit for an isolation driver, characterized in that: include: Oscillation module, detection feedback module and switch module; The input end of the oscillation module is connected to an external signal control circuit, and the two output ends of the oscillation module are connected to an external transformer for generating a sinusoidal signal to be output to the transformer; The two detection ends of the detection feedback module are connected to the two output ends of the oscillation module in a one-to-one correspondence, and the regulation end of the detection feedback module is connected to the input end of the oscillation module through a switch module, which is used to adjust the switch of the switch module according to the jump state of the common mode voltage when a jump occurs in the common mode voltage output by the oscillation module is detected to adjust the gain of the oscillation module so that the oscillation module always keeps oscillating.

2. The modulation circuit for isolating a driver according to claim 1, characterized in that: The detection feedback module includes a PMOS tube M9, a PMOS tube M10, an NMOS tube M11, a capacitor C2 and a first control unit One Shot; The gate of the PMOS tube M9 and the gate of the PMOS tube M10 are two detection terminals of the detection feedback module; The source of the PMOS tube M9 is connected to the source of the PMOS tube M10, and both are connected to the power supply voltage; The drain of the PMOS tube M9 is connected to the drain of the PMOS tube M10, and the connection point is connected to the drain of the NMOS tube M11; The drain of the NMOS tube M11 is also connected to the positive electrode of the capacitor C2, and the connection point is connected to the input end of the first control unit One Shot, and the output end of the first control unit One Shot serves as the control end; The source of the NMOS tube M11 is connected to the negative electrode of the capacitor C2, and the connection point is grounded.

3. The modulation circuit for isolating a driver according to claim 1, characterized in that: The detection feedback module includes PMOS tubes M12-15, NMOS tubes M16-M22 and a second control unit One Shot; The source of the PMOS tube M12, the source of the PMOS tube M13, the source of the PMOS tube M14 and the source of the PMOS tube M15 are connected and are all connected to the power supply voltage; The gate of the PMOS tube M12 is connected to the gate of the PMOS tube M13, and the drain of the PMOS tube M13 is connected to the gate of the PMOS tube M13, the drain of the PMOS tube M14, the drain of the NMOS tube M16, and the drain of the NMOS tube M18; The drain of the PMOS tube M12 is connected to the drain of the NMOS tube M20, and the connection point is connected to the second control unit OneShot, and the output end of the second control unit One Shot serves as the control end; The gate of the PMOS tube M14 is connected to the gate of the PMOS tube M15, and the drain of the PMOS tube M15 is connected to the gate of the PMOS tube M15, the drain of the NMOS tube M19, and the drain of the NMOS tube M17; The gate of the NMOS tube M16 is connected to the gate of the NMOS tube M19, and the connection point is a detection terminal; The gate of the NMOS tube M17 is connected to the gate of the NMOS tube M18, and the connection point is another detection terminal; The source of the NMOS tube M16 is connected to the source of the NMOS tube M17, and the connection point is connected to the drain of the NMOS tube M21; The source of the NMOS tube M18 is connected to the source of the NMOS tube M19, and the connection point is connected to the drain of the NMOS tube M22; The gate of the NMOS tube M20, the gate of the NMOS tube M21, and the gate of the NMOS tube M22 are all connected to the power supply VB; the source of the NMOS tube M20, the source of the NMOS tube M21, and the source of the NMOS tube M22 are all grounded.

4. The modulation circuit for isolating a driver according to claim 2 or 3, characterized in that: The detection feedback module further includes: a bias module, which is used to provide a bias current so that the detection feedback module is biased within a specified range and the differential signal output by the oscillation module can be detected.

5. The modulation circuit for isolating a driver according to claim 2 or 3, characterized in that: The oscillation module is an LC oscillator or a ring oscillator.

6. The modulation circuit for isolating a driver according to claim 5, characterized in that: When the oscillation module is an LC oscillator, the switch module includes: an NMOS tube M8; The gate of the NMOS tube M8 is connected to the regulating end, the source of the NMOS tube M8 is grounded, and the NMOS tube M8 is connected in parallel with the regulating resistor R1 of the LC oscillator.

7. The modulation circuit for isolating a driver according to claim 6, characterized in that: The LC oscillator comprises a first cross-coupled pair of transistors and a second cross-coupled pair of transistors connected in parallel, the first cross-coupled pair of transistors is connected to R1, and the second cross-coupled pair of transistors is connected to a power supply; When a voltage jump from low to high occurs on the demodulation circuit side, the jump voltage injects current into the oscillation module through the transformer so that the common mode voltage is pulled up. When the common mode voltage is pulled up to the first clamping voltage, the input end of the first control unit One Shot changes from a high level to a low level, triggering the output end of the first control unit to output a pulse signal, turning on the NMOS tube M8 and maintaining the on time, so as to continue to maintain oscillation through the NMOS tube M8 and the first cross-coupling pair tube; When the voltage jumps from high to low on the demodulation circuit side, the jump voltage draws current from the oscillation module through the transformer, so that the common-mode voltage is pulled down. When the common-mode voltage is pulled down to the second clamping voltage, the input end of the first control unit One Shot maintains a high level, and the output of the first control unit is not triggered. The NMOS tube M8 remains turned off, and the oscillation module switches the second cross-coupling pair of tubes to maintain oscillation.

8. The modulation circuit for isolating a driver according to claim 5, characterized in that: When the oscillation module is a ring oscillator, the switch module includes: a PMOS tube M30, a PMOS tube M32, an NMOS tube M54 and an NMOS tube M56; The ring oscillator comprises a ring oscillator body circuit, a first-stage driving circuit and a second-stage driving circuit; The second-stage driving circuit includes two driving sub-circuits corresponding to the two differential signals one by one; the first driving sub-circuit includes a PMOS tube M29, a PMOS tube M38, an NMOS tube M45 and an NMOS tube M53; the second driving sub-circuit includes a PMOS tube M31, a PMOS tube M39, an NMOS tube M45 and an NMOS tube M55; The sources of the PMOS tubes M29 to M32 are all connected, and the sources of the NMOS tubes M53 to M56 are all connected; The drain of the PMOS tube M29 is connected to the drain of the PMOS tube M30, and both are connected to the source of the PMOS tube M38; the drain of the PMOS tube M38 is connected to the drain of the NMOS tube M45; the gate of the PMOS tube M38 is connected to the gate of the NMOS tube M45; The drain of the NMOS tube M53 is connected to the drain of the NMOS tube M54, and both are connected to the source of the NMOS tube M45; The drain of the PMOS tube M31 is connected to the drain of the PMOS tube M32, and both are connected to the source of the PMOS tube M39; the drain of the PMOS tube M39 is connected to the drain of the NMOS tube M46; the gate of the PMOS tube M39 is connected to the gate of the NMOS tube M46; The drain of the NMOS tube M55 is connected to the drain of the NMOS tube M56, and both are connected to the source of the NMOS tube M46; The regulating end includes a first regulating end INn and a second regulating end INp; The gates of the PMOS tube M30 and the PMOS tube M32 are both connected to the first regulating terminal INp. The gates of the NMOS tube M54 and the NMOS tube M56 are both connected to the second regulating terminal INn.

9. An isolation driver, characterized in that: include: A signal control circuit, a modulation circuit for isolating a driver as claimed in any one of claims 1 to 8, a transformer, a demodulation circuit and a power driving circuit connected in series in sequence.

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