Digital isolator

Abstract

The embodiment of the application discloses a kind of digital isolators, the digital isolator includes encoding circuit, isolation element, differential circuit and decoding circuit, the encoding circuit receives input digital signal, and encoding signal is generated according to input digital signal, isolation element includes primary winding, first secondary winding and second secondary winding, primary winding receives encoding signal, first secondary winding generates the first differential signal in phase with encoding signal by electromagnetic induction, second secondary winding generates the second differential signal by electromagnetic induction, and the second differential signal is opposite to encoding signal, differential circuit generates difference signal according to the first differential signal and the second differential signal, and decoding signal receives difference signal and decodes target digital signal. Thus, by the digital isolator of differential transmission structure transmission input digital signal, common-mode interference can be effectively eliminated, and the anti-interference performance of digital isolator is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to a kind of digital isolator. BACKGROUND

[0002] Digital isolator is a kind of device when digital signal and analog signal are transmitted in electronic system, it has very high resistance isolation characteristics, to realize the isolation between electronic system and user, multiple optical coupling, inductance / magnetic isolation and capacitive isolation are used. Circuit designers introduce isolation, in order to meet safety requirements or reduce ground loop noise etc. Current isolation ensures that data transmission is not through electrical connection or leakage path, so as to avoid safety risks. SUMMARY

[0003] Therefore, the purpose of the embodiment of the present application is to provide a kind of digital isolator, to improve its anti-interference ability.

[0004] The embodiment of the present application provides a kind of digital isolator, the digital isolator includes:

[0005] Encoding circuit, for receiving input digital signal, and according to the input digital signal generation encoding signal;

[0006] Isolation element, including primary winding, first secondary winding and second secondary winding, the primary winding is connected to the encoding circuit, for receiving the encoding signal;The first secondary winding and the second secondary winding are coupled in electrically isolated manner with the primary winding, the first secondary winding is used to generate the first differential signal in phase with the encoding signal by electromagnetic induction, and the second secondary winding is used to generate the second differential signal by electromagnetic induction. The encoding signal is opposite;

[0007] Difference circuit, for receiving the first differential signal and second differential signal, and according to the first differential signal and second differential signal generation difference signal;

[0008] Decoding circuit, connected to the difference circuit, for receiving the difference signal and decoding output target digital signal.

[0009] Further, the difference circuit is differential amplifier;

[0010] The same name end of the primary winding is connected to the encoding circuit, and the other end is connected to primary ground;

[0011] The same name end of the first secondary winding is connected to the same phase input end of the differential amplifier, and the other end is connected to secondary ground;

[0012] The same name end of the second secondary winding is connected to secondary ground, and the other end is connected to the opposite phase input end of the differential amplifier.

[0013] Further, the primary winding is a planar coil, and the first and second secondary windings are planar coils arranged side by side and wound in the same direction.

[0014] The primary winding comprises a first part wound in a first direction and a second part wound in a second direction in a side-by-side region of the first part, the first direction being different from the second direction.

[0015] The first secondary winding is arranged relative to the first part, and the second secondary winding is arranged relative to the second part.

[0016] Further, the primary winding is a planar coil, and the first and second secondary windings are planar coils arranged side by side and wound in different directions.

[0017] The primary winding comprises a first part wound in a first direction and a second part wound in the first direction in a side-by-side region of the first part.

[0018] The first secondary winding is arranged relative to the first part, and the second secondary winding is arranged relative to the second part.

[0019] Further, the primary winding is a planar coil, and the first and second secondary windings are planar coils arranged side by side and wound in different directions.

[0020] Further, the digital isolator further comprises:

[0021] A first buffer, an input end of the first buffer being connected to the encoding circuit, and an output end of the first buffer being connected to a like-named end of the primary winding.

[0022] Further, the differential circuit is a differential amplifier.

[0023] The primary winding comprises a first primary winding and a second primary winding.

[0024] The first primary winding is electromagnetically coupled to the first secondary winding for receiving the encoding signal.

[0025] The second primary winding is electromagnetically coupled to the second secondary winding for receiving an inverted signal of the encoding signal.

[0026] Further, a like-named end of the first primary winding is connected to the encoding circuit, and the other end is connected to a primary ground.

[0027] A like-named end of the second primary winding is connected to the encoding circuit, and the other end is connected to a primary ground.

[0028] The same end of the first secondary winding is connected to the non-inverting input of the differential amplifier, and the other end is connected to the secondary ground, for receiving the encoded signal;

[0029] The same end of the second secondary winding is connected to the inverting input of the differential amplifier, and the other end is connected to the secondary ground, for receiving the inverted signal of the encoded signal.

[0030] Further, the differential circuit is a differential amplifier;

[0031] The primary winding comprises a first primary winding and a second primary winding;

[0032] The first primary winding is electromagnetically coupled with the first secondary winding, for receiving the encoded signal;

[0033] The second primary winding is electromagnetically coupled with the second secondary winding, for receiving the encoded signal.

[0034] Further, the same end of the first primary winding is connected to the encoding circuit, and the other end is connected to the primary ground;

[0035] The same end of the second primary winding is connected to the encoding circuit, and the other end is connected to the primary ground;

[0036] The same end of the first secondary winding is connected to the non-inverting input of the differential amplifier, and the other end is connected to the secondary ground, for receiving the encoded signal;

[0037] The same end of the second secondary winding is connected to the secondary ground, and the other end is connected to the inverting input of the differential amplifier, for receiving the inverted signal of the encoded signal.

[0038] Further, the primary winding is a planar coil arranged side by side and wound in the same direction;

[0039] The first secondary winding and the second secondary winding are planar coils arranged side by side and wound in the same direction.

[0040] Further, the digital isolator further comprises:

[0041] The input end of the second buffer is connected to the encoding circuit, and the output end is connected to the same end of the first primary winding, for transmitting the encoded signal;

[0042] The input end of the third buffer is connected to the encoding circuit, and the output end is connected to the same end of the second primary winding, for transmitting the inverted signal of the encoded signal.

[0043] The technical scheme of the embodiment of the present application sets two windings in the secondary side, one of which outputs the signal in phase with the encoding signal of the encoding circuit of the digital isolator, and the other outputs the signal in reverse phase with the encoding signal of the encoding circuit of the digital isolator, and then differentiates the two signals through a differential circuit, which can effectively eliminate common-mode interference and improve the anti-interference performance of the digital isolator. BRIEF DESCRIPTION OF DRAWINGS

[0044] The above and other objects, features and advantages of the present application will become more apparent from the following description of the embodiments of the present application taken with reference to the accompanying drawings, in which:

[0045] Figure 1 is a block diagram of an existing digital isolator;

[0046] Figure 2 is a circuit schematic diagram of a digital isolator of the first embodiment of the present application;

[0047] Figure 3 is a circuit schematic diagram of another digital isolator of the first embodiment of the present application;

[0048] Figure 4 is a coil arrangement schematic diagram of an isolation element of one implementation of the embodiment of the present application;

[0049] Figure 5 is a coil arrangement schematic diagram of an isolation element of another implementation of the embodiment of the present application;

[0050] Figure 6 is a coil arrangement schematic diagram of an isolation element of another implementation of the embodiment of the present application;

[0051] Figure 7 is a circuit schematic diagram of a digital isolator of the second embodiment of the present application;

[0052] Figure 8 is an equivalent circuit diagram of an isolation element of the embodiment of the present application considering parasitic parameters;

[0053] Figure 9 is a coil arrangement schematic diagram of an isolation element of the embodiment of the present application;

[0054] Figure 10 is a circuit schematic diagram of a digital isolator of the third embodiment of the present application. DETAILED DESCRIPTION

[0055] The present application is described below based on examples, but the present application is not limited to these examples only. In the following detailed description of the present application, some specific details are described in detail. The present application can also be fully understood without the description of these details by those skilled in the art. In order to avoid confusion of the essence of the present application, the well-known methods, processes, procedures, elements and circuits are not described in detail.

[0056] In addition, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0057] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is said to be "connected to" another element or said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be intermediate elements, and the connection between elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0058] Unless the context clearly requires otherwise, the use of the term "comprise," "comprises," or "comprising" in the specification is intended to be interpreted as the inclusion of the stated elements or steps, but not the exclusion of other elements or steps. That is, it is "including but not limited to."

[0059] In the description of the present application, it should be understood that the terms "first", "second" and the like are used only for the purpose of description and should not be understood as indicating or implying relative importance. In addition, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise stated.

[0060] Figure 1 is a block diagram of an existing digital isolator. As shown in Figure 1 , the digital isolator includes an encoding circuit 1, an isolation element 2 and a decoding circuit 3. Among them, the encoding circuit 1 receives an input digital signal DIN and generates an encoding signal according to the input digital signal DIN. The digital isolator 2 uses a transformer or a capacitor, and transmits the encoding signal to the decoding circuit through electromagnetic induction between the primary side and the secondary side of the transformer. The received decoding signal is decoded by the decoding circuit 3 to obtain the target digital signal DOUT corresponding to the input digital signal DIN, realizing the electrical isolation transmission of the digital signal.

[0061] Figure 2 is a circuit schematic diagram of a digital isolator of the first embodiment of the present application. As shown in Figure 2As shown, the digital isolator in this embodiment of the invention includes an encoding circuit 1, an isolation element 2, a differential circuit 4, and a decoding circuit 3. The encoding circuit 1 receives the input digital signal DIN and generates an encoded signal based on DIN. The encoded signal can be a pulse signal formed by encoding the rising or falling edge of the input digital signal DIN. The isolation element 2 includes a primary winding L1 and a first secondary winding L... 21 Second secondary winding L 22 The primary winding L1 is connected to the encoding circuit and is used to receive the encoded signal. The first secondary winding L... 21 Second secondary winding L 22 It is electrically isolated from the primary winding L1. The first secondary winding L... 21 The second secondary winding L is used to generate a first differential signal in phase with the encoded signal through electromagnetic induction. 22 The differential circuit 4 is used to generate a second differential signal that is inverted from the encoded signal through electromagnetic induction. The differential circuit 4 receives the first and second differential signals and generates a difference signal based on them. The decoding circuit 3 is connected to the differential circuit 4 and receives the difference signal, decodes it, and outputs the target digital signal DOUT.

[0062] The technical solution of this embodiment sets two windings on the secondary side. One secondary winding outputs a signal that is in phase with the encoded signal of the digital isolator's encoding circuit, and the other secondary winding outputs a signal that is out of phase with the encoded signal of the digital isolator's encoding circuit. Then, the two signals are differentially divided by a differential circuit, which can effectively eliminate common-mode interference and improve the anti-interference performance of the digital isolator.

[0063] In this embodiment, as Figure 2 As shown, the primary side has one primary winding. Simultaneously, the secondary side has two secondary windings, namely the first secondary winding L. 21 Second secondary winding L 22 Differential circuit 4 is a differential amplifier. The same-name terminal of the primary winding L1 is connected to the encoding circuit 1, and the other terminal is connected to the primary ground. The first secondary winding L... 21 The same-name terminal is connected to the non-inverting input of the differential amplifier, and the other end is connected to the secondary ground. The second secondary winding L... 22 The same-named terminal of the first secondary winding is connected to the secondary ground, and the other end is connected to the inverting input of the differential amplifier. That is, the first secondary winding L... 21 Second secondary winding L 22 The connection method of the same-name terminals is reversed, therefore, the first secondary winding L 21 The signal generated by induction is in phase with the input signal of the primary winding, and the second secondary winding L... 22The signal generated by induction is opposite to the input signal of the primary winding, and then a differential signal can be generated in the secondary side. In addition, since common mode noise is usually generated in the transmission of the isolation element, whether it is the in-phase signal of the encoded signal or the anti-phase signal of the encoded signal, the same phase common mode noise will be transmitted through the isolation element, therefore, by taking the difference value of the differential signal in the differential amplifier, the common mode noise carried in the two signals can be removed, effectively eliminating the common mode interference and improving the anti-interference performance of the digital isolator.

[0064] Further, in an optional implementation, as shown in Figure 3 , the digital isolator further comprises a first buffer 5. The input end of the first buffer 5 is connected to the encoding circuit, and the output end is connected to the like end of the primary winding L1. Thus, the encoded signal output by the encoding circuit is enhanced through the first buffer, so that the signal strength in the subsequent signal transmission process is enhanced, which is beneficial to further improve the signal transmission quality.

[0065] At the same time, in order to meet the demand of miniaturization, the winding can be set as a planar coil, and can be set in different forms according to the demand of the embodiment.

[0066] Figure 4 is a schematic diagram of the coil arrangement of the isolation element in an implementation of the embodiment. In the Figure 4 implementation shown, the primary winding L1 is a planar coil. The first secondary winding L 21 and the second secondary winding L 22 are planar coils arranged side by side and wound in the same direction. The primary winding L1 comprises a first part A wound in a first direction and a second part B wound in a second direction in the side-by-side area of the first part A, and the first direction and the second direction are different. The first secondary winding L 21 is arranged relative to the first part A. The second secondary winding L 22 is arranged relative to the second part B. Optionally, when the first direction is a clockwise direction, the second direction is a counterclockwise direction. The first part A of the primary winding L1 is wound in a clockwise direction from the like end (P end shown in the figure), and the second part B is wound in a counterclockwise direction from the end of the first part A. The first secondary winding L 21 and the second secondary winding L 22 are both wound in a clockwise direction from the like end (P end shown in the figure). Thus, by arranging the primary winding, the first secondary winding and the second secondary winding in the above-mentioned winding manner, the first secondary winding and the second secondary winding generate a first differential signal in phase with the encoded signal and a second differential signal opposite to the encoded signal, respectively, through electromagnetic induction.

[0067] Further, in the embodiment, the first secondary winding L 21 and the second secondary winding L22 An insulating material is arranged between the primary winding and the secondary winding to reduce mutual influence in the electromagnetic induction process. Specifically, the insulating material can be polyimide (commonly known as nylon), SiO2, or Si3N4.

[0068] In this embodiment, by dividing the primary winding into two parts that are arranged side by side and wound in different directions, the primary winding can be effectively coupled to the two secondary windings in an anti-phase manner, so as to generate anti-phase signals in the secondary windings. Meanwhile, the primary winding, the first secondary winding, and the second secondary winding can be planar metal patterns, so that the isolation structure can be formed on a circuit board or a wafer.

[0069] Figure 5 is a schematic diagram of a coil arrangement of an isolation element in another implementation of the present application. In the implementation shown in Figure 5 , the primary winding L1 is a planar coil, the first secondary winding L 21 and the second secondary winding L 22 are planar coils arranged side by side and wound in different directions. The primary winding L1 includes a first part A wound in a first direction and a second part B wound in the first direction in a region arranged side by side with the first part A. The first secondary winding L 21 is arranged relative to the first part, and the second secondary winding L 22 is arranged relative to the second part B. Further, in this embodiment, the first part A and the second part B of the primary winding L1 are both wound in a clockwise direction. The first secondary winding L 21 is wound in a clockwise direction starting from the like end (the P end shown in the figure), and the second secondary winding L 22 is wound in a counterclockwise direction starting from the like end (the P end shown in the figure). In this way, by arranging the primary winding, the first secondary winding, and the second secondary winding in the above-described coil winding manner, the first secondary winding and the second secondary winding generate a first differential signal in phase with the encoding signal and a second differential signal anti-phase with the encoding signal, respectively, through electromagnetic induction.

[0070] In this embodiment, by dividing the primary winding into two parts arranged side by side and winding the secondary winding in different directions, the primary winding can be effectively coupled to the two secondary windings in an anti-phase manner, so as to generate anti-phase signals in the secondary windings.

[0071] Figure 6 is a schematic diagram of a coil arrangement of an isolation element in another implementation of the present application. In the implementation shown in Figure 6 , the primary winding L1 is a planar coil. The first secondary winding L 21 and the second secondary winding L 22The planar coils are arranged in mutual overlapping or nesting and are wound in the same direction. Further, the primary winding L1 in the embodiment is a planar coil wound in the clockwise direction. The first secondary winding L 21 and the second secondary winding L 22 are wound in parallel in the clockwise direction to form the nested planar coils. In order to reduce the mutual influence between the first secondary winding L 21 and the second secondary winding L 22 , an insulating material such as polyimide (commonly known as nylon), SiO2 or Si3N4 is arranged between the first secondary winding L 21 and the second secondary winding L 22 .

[0072] In the embodiment, the primary winding, the first secondary winding and the second secondary winding are arranged by the above-mentioned winding modes so that the first secondary winding and the second secondary winding respectively generate the first differential signal in phase with the encoded signal and the second differential signal in opposite phase with the encoded signal through electromagnetic induction. Meanwhile, the above-mentioned winding modes provide flexible selection for the arrangement of the digital isolator, which is conducive to improving the applicability of the digital isolator.

[0073] Figure 7 is a circuit schematic diagram of the digital isolator of the second embodiment of the present application. As shown in Figure 7 , the digital isolator in the embodiment includes an encoding circuit 1, an isolation element 2, a differential circuit 4 and a decoding circuit 3. The encoding circuit 1 is configured to receive an input digital signal DIN and generate encoded signals DIN+ and DIN- according to the input digital signal DIN. The isolation element 2 includes a primary winding L1, a first secondary winding L 21 and a second secondary winding L 22 . The primary winding L1 includes a first primary winding L 11 and a second primary winding L 12 . The first primary winding L 11 is electromagnetically coupled with the first secondary winding L 21 to receive the encoded signal DIN+. The second primary winding L 12 is electromagnetically coupled with the second secondary winding L 22 to receive the inverted encoded signal DIN-. The differential circuit 4 is a differential amplifier configured to receive the encoded signal DIN+ transmitted by the first secondary winding L 21 and the inverted encoded signal DIN- transmitted by the second secondary winding L 22 and generate a difference signal according to the received signals. The decoding circuit 3 is connected with the differential amplifier and configured to receive the difference signal and decode and output a target digital signal DOUT.

[0074] The technical scheme of the embodiment of the present application adjusts the primary side in the original transformer isolation element to a structure comprising a first primary winding and a second primary winding, and adjusts the secondary side to a structure comprising a first secondary winding and a second secondary winding, generates a first differential signal in phase with the encoding signal and a second differential signal opposite to the encoding signal through the first secondary winding and the second secondary winding respectively, and generates a difference signal through a differential circuit according to the first differential signal and the second differential signal, so as to realize differential transmission of the encoding signal, utilize the common mode rejection capability advantage of the differential signal transmission, improve the signal strength during signal transmission, and improve the anti-interference capability of the digital isolator, and is beneficial to improving the quality of digital signal transmission.

[0075] Further, as shown in Figure 7 , the digital isolator of the embodiment further comprises a second buffer 6 and a third buffer 7. The input end of the second buffer 6 is connected to the encoding circuit, and the output end is connected to the like-named end of the first primary winding, for transmitting the encoding signal. The input end of the third buffer 7 is connected to the encoding circuit, and the output end is connected to the like-named end of the second primary winding, for transmitting the inverse signal of the encoding signal. Thus, the second buffer and the third buffer respectively enhance the encoding signal and the inverse signal of the encoding signal output by the encoding circuit, so that the signal strength in the subsequent signal transmission process is improved, which is beneficial to further improving the signal transmission quality.

[0076] Optionally, as shown in Figure 7 , in the embodiment, the like-named end of the first primary winding L 11 is connected to the encoding circuit, and the other end is connected to the primary ground. The like-named end of the second primary winding L 12 is connected to the encoding circuit, and the other end is connected to the primary ground. The like-named end of the first secondary winding L 21 is connected to the non-inverting input end of the differential amplifier, and the other end is connected to the secondary ground, for receiving the encoding signal. The like-named end of the second secondary winding L 22 is connected to the inverting input end of the differential amplifier, and the other end is connected to the secondary ground, for receiving the inverse signal of the encoding signal. The first primary winding L 11 is connected to the first secondary winding L 21 , and the second primary winding L 12 is connected to the second secondary winding L 22The electromagnetic coupling can be realized by using one or two different cores. Thus, the digital isolator with the differential transmission structure constructed by the above connection mode improves the anti-interference ability of the digital isolator, and realizes high-quality transmission of the input digital signal. Moreover, the encoding signal and the inverse signal of the encoding signal are respectively transmitted through the first primary winding and the second primary winding, which can ensure the effectiveness and accuracy of the information in the transmission process of the encoding signal, reduce signal interference, further improve the anti-interference ability of the digital isolator, and improve the transmission quality of the input digital signal.

[0077] Figure 8 is an equivalent circuit diagram of the isolation element after considering the parasitic parameters in the embodiment of the application. The circuit diagram of the equivalent isolation element is shown in Figure 7 , and the circuit diagram of the equivalent isolation element after considering the parasitic parameters is shown in Figure 8 . As shown in the figure, the isolation element 2 can be equivalent to an oscillation circuit containing input and output capacitors and common-mode capacitors. When the encoding signal DIN+ and the inverse signal of the encoding signal DIN- are input to the two input terminals of the isolation element 2 respectively, oscillation signals will be generated between the signal lines of the two channels and the ground. Due to the matching of the impedances of the two channels, the first differential signal and the second differential signal output to the differential amplifier 4 are basically consistent. At the same time, the differential amplifier 4 can perform differential processing on the first differential signal and the second differential signal, so as to offset the oscillation influence and improve the common-mode rejection ability of the digital isolator.

[0078] Figure 9 is a schematic diagram of the coil arrangement of the isolation element in the embodiment of the application. As shown in the figure, the primary winding is a flat coil arranged side by side and wound in the same direction. The first secondary winding and the second secondary winding are flat coils arranged side by side and wound in the same direction. Figure 9

[0079] Further, the first primary winding L 11 , the second primary winding L 12 , the first secondary winding L 21 and the second secondary winding L 22 in the embodiment are flat coils wound in the clockwise direction from the same end (P end shown in the figure). Thus, the first primary winding, the second primary winding, the first secondary winding and the second secondary winding are arranged by the above winding mode, so that the first secondary winding and the second secondary winding generate the first differential signal in phase with the encoding signal and the second differential signal in inverse phase with the encoding signal respectively through electromagnetic induction. At the same time, the first secondary winding L 21 and the second secondary winding L 22 , and the first secondary winding L 21 and the second secondary winding L 22 ​polyimide (commonly known as nylon), SiO2or Si3N4type insulating material is arranged between the first secondary winding L 21 and the second secondary winding L 22 to reduce mutual influence between the first secondary winding L 21 and the second secondary winding L 22 during digital signal transmission.

[0080] Figure 10 is a circuit schematic diagram of the digital isolator of the third embodiment of the present application. As shown in Figure 10 , the digital isolator in this embodiment includes an encoding circuit 1, an isolation element 2, a differential circuit 4 and a decoding circuit 3. The encoding circuit 1 is used to receive an input digital signal DIN and generate an encoded signal DIN+ according to the input digital signal DIN. The isolation element 2 includes a primary winding L1, a first secondary winding L 21 and a second secondary winding L 22 . The primary winding L1 includes a first primary winding L 11 and a second primary winding L 12 . The first primary winding L 11 is electromagnetically coupled with the first secondary winding L 21 and is used to receive the encoded signal DIN+. The second primary winding L 12 is electromagnetically coupled with the second secondary winding L 22 and is used to receive the encoded signal DIN+. The differential circuit 4 is a differential amplifier used to receive the encoded signal DIN+ transmitted by the first secondary winding L 21 and the second secondary winding L 22 and generate a difference signal according to the received signal. The decoding circuit 3 is connected with the differential amplifier and is used to receive the difference signal and decode and output a target digital signal DOUT. Further, in this embodiment, the same-named end of the first primary winding L 11 is connected to the encoding circuit and the other end is connected to the primary ground. The same-named end of the second primary winding L 12 is connected to the encoding circuit and the other end is connected to the primary ground. The same-named end of the first secondary winding L 21 is connected to the non-inverting input end of the differential amplifier and the other end is connected to the secondary ground for receiving the encoded signal. The same-named end of the second secondary winding L 22 is connected to the secondary ground and the other end is connected to the inverting input end of the differential amplifier for receiving the inverted signal of the encoded signal. The first primary winding L 11 and the first secondary winding L 21 and the second primary winding L 12 and the second secondary winding L 22The electromagnetic coupling can be realized by using one or two different cores. Thus, the digital isolator with the differential transmission structure constructed by the above connection mode improves the anti-interference ability of the digital isolator and realizes high-quality transmission of the input digital signal. Moreover, the first primary winding and the second primary winding in the primary winding respectively transmit the encoded signal to the first secondary winding and the second secondary winding, which can ensure the effectiveness and accuracy of the information in the encoded signal transmission process, reduce signal interference, further improve the anti-interference ability of the digital isolator, and improve the transmission quality of the input digital signal.

[0081] Further, as shown in Figure 10 The digital isolator further includes a second buffer 6. The input end of the second buffer 6 is connected to the encoding circuit, and the output end is connected to the like end of the first primary winding for transmitting the encoded signal. Thus, the second buffer enhances the encoded signal output by the encoding circuit, so that the signal strength in the subsequent signal transmission process is improved, which is beneficial to further improve the signal transmission quality.

[0082] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A digital isolator, comprising: The digital isolator comprises: an encoding circuit configured to receive an input digital signal and generate an encoded signal according to the input digital signal; an isolation element comprising a primary winding, a first secondary winding and a second secondary winding, the primary winding having a same-name end connected to the encoding circuit and another end connected to a primary ground for receiving the encoded signal, the first secondary winding and the second secondary winding being coupled to the primary winding in an electrically isolated manner, the first secondary winding being configured to generate a first differential signal in phase with the encoded signal through electromagnetic induction, and the second secondary winding being configured to generate a second differential signal out of phase with the encoded signal through electromagnetic induction; a differential circuit configured to receive the first differential signal and the second differential signal and generate a difference signal according to the first differential signal and the second differential signal; a decoding circuit connected to the differential circuit and configured to receive the difference signal and decode and output a target digital signal.

2. The digital isolator of claim 1, wherein, The differential circuit is a differential amplifier. The same-name end of the first secondary winding is connected to a non-inverting input end of the differential amplifier, and the other end is connected to a secondary ground. The same-name end of the second secondary winding is connected to the secondary ground, and the other end is connected to an inverting input end of the differential amplifier.

3. The digital isolator of claim 2, wherein, The primary winding is a planar coil, and the first secondary winding and the second secondary winding are planar coils arranged side by side and wound in the same direction. The primary winding comprises a first part wound in a first direction and a second part wound in a second direction in a side-by-side region of the first part, and the first direction is different from the second direction. The first secondary winding is arranged relative to the first part, and the second secondary winding is arranged relative to the second part.

4. The digital isolator of claim 2, wherein, The primary winding is a planar coil, and the first secondary winding and the second secondary winding are planar coils arranged side by side and wound in different directions. The primary winding comprises a first part wound in a first direction and a second part wound in the first direction in a side-by-side region of the first part. The first secondary winding is arranged relative to the first part, and the second secondary winding is arranged relative to the second part.

5. The digital isolator of claim 2, wherein, The primary winding is a planar coil, and the first secondary winding and the second secondary winding are planar coils arranged side by side and wound in different directions.

6. The digital isolator of claim 1, wherein, The digital isolator further comprises: a first buffer, an input end of the first buffer being connected to the encoding circuit, and an output end of the first buffer being connected to the same-name end of the primary winding.

7. The digital isolator of claim 1, wherein, The differential circuit is a differential amplifier. The primary winding comprises a first primary winding and a second primary winding. The first primary winding is electromagnetically coupled to the first secondary winding for receiving the encoded signal. The second primary winding is electromagnetically coupled to the second secondary winding for receiving an inverted signal of the encoded signal.

8. The digital isolator of claim 7, wherein, The same-name end of the first primary winding is connected to the encoding circuit, and the other end is connected to a primary ground. The same-name end of the second primary winding is connected to the encoding circuit, and the other end is connected to a primary ground. The same-name end of the first secondary winding is connected to a non-inverting input end of the differential amplifier, and the other end is connected to a secondary ground for receiving the encoded signal. The same name end of the second secondary winding is connected to the inverting input end of the differential amplifier, and the other end is connected to the secondary ground, for receiving the inverted signal of the encoding signal.

9. The digital isolator of claim 1, wherein, The differential circuit is a differential amplifier; The primary winding comprises a first primary winding and a second primary winding; The first primary winding is electromagnetically coupled with the first secondary winding, for receiving the encoding signal; The second primary winding is electromagnetically coupled with the second secondary winding, for receiving the encoding signal.

10. The digital isolator of claim 9, wherein, The same name end of the first primary winding is connected to the encoding circuit, and the other end is connected to the primary ground; The same name end of the second primary winding is connected to the encoding circuit, and the other end is connected to the primary ground; The same name end of the first secondary winding is connected to the non-inverting input end of the differential amplifier, and the other end is connected to the secondary ground, for receiving the encoding signal; The same name end of the second secondary winding is connected to the secondary ground, and the other end is connected to the inverting input end of the differential amplifier, for receiving the inverted signal of the encoding signal.

11. The digital isolator of claim 10, wherein, The primary winding is a planar coil arranged side by side and wound in the same direction; The first secondary winding and the second secondary winding are planar coils arranged side by side and wound in the same direction.

12. The digital isolator of claim 7, wherein, The digital isolator further comprises: A second buffer, the input end of the second buffer is connected to the encoding circuit, and the output end is connected to the same name end of the first primary winding, for transmitting the encoding signal; A third buffer, the input end of the third buffer is connected to the encoding circuit, and the output end is connected to the same name end of the second primary winding, for transmitting the inverted signal of the encoding signal.

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