Optimally matched digital isolator and application circuit thereof

Abstract

The invention provides an optimized matching digital isolator and an application circuit thereof. A first matching network and / or a second matching network in the digital isolator with a return function are / is an RF transformer; the RF transformer comprises a first winding, a second winding and a third winding; the first winding is connected with a corresponding signal amplifier, the second winding is connected with a corresponding antenna, and the third winding is connected with a corresponding envelope detector. The second matching network is preferably a second RF transformer; a first winding in the second RF transformer is connected with the second signal amplifier, a second winding is connected with the second coupling piece, and a third winding is connected with the second envelope detector. Aiming at a digital isolation circuit for realizing two-way communication based on a single-pair coupling transmission structure, the isolation circuit is provided with the RF transformer for network matching, so that impedance coordination, signal reflection elimination and maximum power transmission signal energy of a coupling piece, an envelope detector and a signal amplifier can be realized, and meanwhile, the system performance is improved.

Description

Technical Field

[0001] This invention relates to the field of isolator technology, and more specifically to optimized matching digital isolators and their application circuits. Background Technology

[0002] In digital isolators with backhaul functionality, such as Figure 1 As shown, the transmitting (TX) and receiving (RX) ends mainly include: signal amplifiers (power amplifiers (PA) or buffers (BUF)), envelope detectors (ED), and coupling components (such as antennas). This enables bidirectional communication between the isolated ends while maintaining normal signal transmission from the transmitting end (TX) to the receiving end (RX) (e.g.,...). Figure 1 The path shown by the purple dashed line and the abnormal signal from the receiver RX to the transmitter TX (such as...) Figure 1 (As shown by the orange dashed line in the middle) direction.

[0003] The aforementioned digital isolator with backhaul capability requires the matching networks in the transmitter (TX) and receiver (RX) ends to be capable of matching both normal and abnormal signals. This means simultaneously matching the envelope detector (ED) with the coupler, and matching the signal amplifier (PA / BUF) with the coupler. This is particularly important for the matching network in the receiver (RX), as it operates through the forward transmission channel (…). Figure 1 The normal signal transmitted from the purple transmission link in the image is relatively fast, so the impedance matching capability of the receiving end RX is more critical, which is a technical challenge in this field.

[0004] The term "matching" refers to impedance matching, which involves adjusting the input and output impedances of electronic devices to meet certain conditions. These conditions typically aim to maximize system transmission power or minimize signal reflection. For example, in a wireless transmission system using a digital isolator, matching the impedances of the transmitting and receiving devices can maximize isolated transmission power, eliminate signal reflection, maximize signal energy transfer, and ensure optimized system performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an optimized matching digital isolator and its application circuit, which can specifically optimize the impedance matching capability of the matching network in the transmitter / receiver of the digital isolator with backhaul function, so as to maximize the isolated bidirectional transmission power.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An optimized matching digital isolator includes a first isolation circuit and a second isolation circuit located on both sides of an isolation strip; the first isolation circuit includes a first coupler, a first matching network, a first envelope detector, and a first signal amplifier; the second isolation circuit includes a second coupler, a second matching network, a second envelope detector, and a second signal amplifier; the first coupler, the first envelope detector, and the first signal amplifier are respectively connected to the first matching network; the second coupler, the second envelope detector, and the second signal amplifier are respectively connected to the second matching network. The second signal amplifier is configured to modulate the received abnormal signal into a high-frequency signal and then send it to the second matching network; The second matching network is configured to receive a normal signal sent from the second coupler, and to send the high-frequency signal out through the second coupler during the low-level gap of the normal signal. The first matching network is configured to receive the high-frequency signal sent by the first coupler and then couple it to the first envelope detector. The first envelope detector is configured to issue a prompt message if it can detect a high-frequency signal in a low-level gap of the coupling signal sent from the first matching network. The first matching network and / or the second matching network is an RF transformer; the RF transformer includes a first winding, a second winding and a third winding; the first winding is connected to the corresponding signal amplifier, the second winding is connected to the corresponding antenna, and the third winding is connected to the corresponding envelope detector.

[0007] Optionally, the second matching network is a second RF transformer; the first winding of the second RF transformer is connected to the second signal amplifier, the second winding is connected to the second coupler, and the third winding is connected to the second envelope detector.

[0008] Optionally, the first matching network is a first RF transformer; the first winding of the first RF transformer is connected to the first signal amplifier, the second winding is connected to the first coupler, and the third winding is connected to the first envelope detector.

[0009] Optionally, the first matching network is a first RF transformer, and the second matching network is a second RF transformer; The first winding of the first RF transformer is connected to the first signal amplifier, the second winding is connected to the first coupler, and the third winding is connected to the first envelope detector. The first winding of the second RF transformer is connected to the second signal amplifier, the second winding is connected to the second coupler, and the third winding is connected to the second envelope detector.

[0010] Optionally, one end of the second winding in the RF transformer adopts a GSSG, GSGSG, or GSG layout, wherein the signal port S is connected to the corresponding coupler.

[0011] Optionally, the front-end circuit of the second envelope detector adopts a common gate architecture; one end of the second winding of the second RF transformer adopts a GSG layout, wherein the signal port S is connected to the second coupler; the output terminal of the second signal amplifier is connected to the first winding of the second RF transformer; and the source of the MOS transistor in the front-end circuit of the second envelope detector is connected to the third winding of the second RF transformer.

[0012] Optionally, the front-end circuit of the second envelope detector adopts a common gate architecture; one end of the second winding of the second RF transformer adopts a GSSG or GSGSG layout, wherein two signal ports S are connected to the second coupler, and one ground port G serves as the center tap of the second RF transformer and is connected to the gate in the front-end circuit of the second envelope detector; the output terminal of the second signal amplifier is connected to the first winding of the second RF transformer; and the source of the MOS transistor in the front-end circuit of the second envelope detector is connected to the third winding of the second RF transformer.

[0013] Optionally, a capacitor is connected between the source of one MOS transistor and the gate of another MOS transistor in the front-end circuit of the second envelope detector.

[0014] Optionally, the front-end circuit of the first envelope detector adopts a common gate architecture; one end of the second winding of the first RF transformer adopts a GSG layout, wherein the signal port S is connected to the first coupler; the output terminal of the first signal amplifier is connected to the first winding of the first RF transformer; and the source of the MOS transistor in the front-end circuit of the first envelope detector is connected to the third winding of the first RF transformer.

[0015] Optionally, the front-end circuit of the first envelope detector adopts a common gate architecture; one end of the second winding of the first RF transformer adopts a GSSG or GSGSG layout, wherein two signal ports S are connected to the first coupler, and one ground port G serves as the center tap of the first RF transformer and is connected to the gate in the front-end circuit of the first envelope detector; the output terminal of the first signal amplifier is connected to the first winding of the first RF transformer; and the source of the MOS transistor in the front-end circuit of the first envelope detector is connected to the third winding of the first RF transformer.

[0016] Optionally, a capacitor is connected between the source and the gate in the front-end circuit of the first envelope detector.

[0017] Optionally, the first isolation circuit is a first millimeter-wave isolation circuit; the second isolation circuit is a second millimeter-wave isolation circuit; the first coupling element is a first millimeter-wave antenna; and the second coupling element is a second millimeter-wave antenna.

[0018] Optionally, the first isolation circuit is a first magnetic coupling isolation circuit or a first capacitive coupling isolation circuit; the second isolation circuit is a second magnetic coupling isolation circuit or a second capacitive coupling isolation circuit; the first coupling element is a first magnetic coupler or a first capacitive coupler; and the second coupling element is a second magnetic coupler or a second capacitive coupler.

[0019] Another technical solution provided by this invention is: An application circuit for an optimized matching digital wave isolator includes the aforementioned optimized matching digital wave isolator; it also includes a first isolated circuit and a second isolated circuit. The first isolated circuit is connected to the first isolated circuit; the second isolated circuit is connected to the second isolated circuit.

[0020] The beneficial effects of this invention are as follows: This invention targets a digital isolation circuit that realizes bidirectional communication based on a single-pair coupling transmission structure. By configuring an RF transformer in the isolation circuit for network matching, it can achieve impedance coordination among the coupler, envelope detector, and signal amplifier, thereby eliminating signal reflection, maximizing the power transmission of signal energy, and improving system performance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the digital isolation circuit for bidirectional communication based on a single-pair coupled transmission structure, as described in this invention. Figure 2 This is a schematic diagram of the RF transformer described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the equivalent circuit structure of the RF transformer described in this embodiment of the invention; Figure 4a -b are schematic diagrams of the working principles of the one-input, two-output RF transformer without a center tap in the embodiments of the present invention; Figure 5a -b are schematic diagrams of two working principles of the one-input, two-output RF transformer with a center tap in the embodiments of the present invention; Figure 6a This is a schematic diagram of the connection relationship when the RF transformer adopts the GSG layout in the embodiment of the present invention; Figure 6b for Figure 6a A schematic diagram of an RF transformer structure that uses cross-coupling technology to improve conversion gain; Figure 7a This is a schematic diagram of the connection relationship when the RF transformer adopts the GSSG layout in the embodiment of the present invention; Figure 7b for Figure 7a A schematic diagram of an RF transformer structure that uses cross-coupling technology to improve conversion gain; Figure 8a This is a schematic diagram of the connection relationship when the RF transformer adopts the GSGSG layout in the embodiment of the present invention; Figure 8b for Figure 8a A schematic diagram of an RF transformer structure that uses cross-coupling technology to improve conversion gain; Figure 9 This is a schematic diagram of the EM model of the RF transformer described in this embodiment of the invention; Figure 10 This is a schematic diagram of the return loss simulation curve of the optimized matching digital wave isolator provided in the embodiment of the present invention.

[0022] Label Explanation: 101. First isolated circuit; 102. Second isolated circuit; 10. First isolation circuit; 20. Second isolation circuit; 11. First coupler; 12. First matching network; 13. First envelope detector; 14. First signal amplifier; 21. Second coupler; 22. Second matching network; 23. Second envelope detector; 24. Second signal amplifier. Detailed Implementation

[0023] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0024] The most crucial concept of this invention lies in the fact that, for digital isolation circuits that achieve bidirectional communication based on a single-pair coupling transmission structure, by configuring RF transformers for at least one isolation circuit (preferably both isolation circuits) for network matching, impedance coordination among the coupler, envelope detector, and signal amplifier can be achieved.

[0025] Please refer to Figure 1 as well as Figure 2 The embodiments of the present invention provide an optimized matching digital isolator.

[0026] like Figure 1 As shown, the digital isolator is a digital isolator capable of transmitting back anomalies, including a first isolation circuit 10 and a second isolation circuit 20 located on both sides of the isolation band; the first isolation circuit 10 includes a first coupler 11, a first matching network 12, a first envelope detector 13, and a first signal amplifier 14; the second isolation circuit 20 includes a second coupler 21, a second matching network 22, a second envelope detector 23, and a second signal amplifier 24; the first coupler 11, the first envelope detector 13, and the first signal amplifier 14 are respectively connected to the first matching network 12; the second coupler 21, the second envelope detector 23, and the second signal amplifier 24 are respectively connected to the second matching network 22.

[0027] The second signal amplifier is configured to modulate the received abnormal signal into a high-frequency signal and then send it to the second matching network. The second matching network is configured to receive a normal signal sent from the second coupler, and to send the high-frequency signal out through the second coupler during the low-level gap of the normal signal. The first matching network is configured to receive the high-frequency signal sent by the first coupler and then couple it to the first envelope detector. The first envelope detector is configured to issue a prompt message if it can detect a high-frequency signal in a low-level gap of the coupling signal sent from the first matching network.

[0028] The working principle of the digital isolator capable of transmitting anomalies is as follows: Under normal transmission conditions, such as Figure 1As shown in the purple transmission link, the first isolated circuit 101 transmits a normal signal (pulse-modulated signal, such as Pulse Width Modulation, PWM) to the first isolation circuit 10 of the digital isolator; the first signal amplifier 14 of the first isolation circuit 10 receives the normal signal and modulates its carrier to a high frequency (the blue signal in the figure), and then sends it to the first matching network 12; after receiving the high-frequency normal signal, the first matching network 12 matches the output impedance of the first coupler 11 to send the high-frequency normal signal out through the first coupler 11 with maximum power; after receiving the high-frequency normal signal (the blue signal in the figure changes from "long" to "short" due to wireless transmission loss), the second coupler 21 of the second isolation circuit 20 performs impedance matching through the second matching network 22 to transmit it to the second envelope detector 23; the second envelope detector 23 demodulates the high-frequency normal signal to restore it to the original frequency normal signal and outputs it to the second isolated circuit 102.

[0029] When any abnormal condition occurs in the second isolated circuit 102, a corresponding abnormal signal will be output to the digital isolator. For example... Figure 1 As shown in the orange transmission link, the abnormal signal will be output to the second signal amplifier 24 in the second isolation circuit 20; for the second signal amplifier 24, what it receives is actually a high-level signal or a short-segment level signal (such as...). Figure 1 The green signal in the middle); the second signal amplifier 24 receives the abnormal signal and obtains the corresponding high-frequency signal through carrier modulation processing (the green signal in the middle); Figure 1 The red signal in the signal is then sent to the second matching network 22; the output impedance of the second coupler 21 is matched by the impedance of the second matching network 22 to maximize the power of the high-frequency abnormal signal at the low-level gap of the normal signal (sent from the second coupler 21). (In fact, this low-level gap is more than...) Figure 1 (The signal shown is longer), and is sent out through the second coupler 21; after receiving the high-frequency abnormal signal sent by the first coupler 11, the first matching network 12 of the first isolation circuit 10 couples and transmits it (coupled into the normal signal emitted by the first signal amplifier 14) to the first envelope detector 13; after receiving the coupled signal, if the first envelope detector 13 can detect the high-frequency abnormal signal in its low-level gap (then it will amplify the high-frequency signal through its amplifier to obtain the green signal in the figure), it will prompt the first isolated circuit 101 connected to it; after receiving the prompt, the first isolated circuit 101 determines that the second isolated circuit 102 has malfunctioned, and promptly controls the shutdown or adjusts the transmission power of the first isolation circuit 10 (changing the signal duty cycle).

[0030] The digital isolator capable of transmitting anomalies can directly utilize a single channel composed of a single pair of couplers to transmit an anomaly from the second isolated circuit to the first isolated circuit when the second isolated circuit needs to transmit an anomaly signal back through the digital isolator to the first isolated circuit, thereby prompting the first isolated circuit to take protective measures.

[0031] In some specific embodiments, the signal amplifier may be a power amplifier (PA) or a buffer (BUFF).

[0032] In some specific embodiments, the first isolation circuit is a first millimeter-wave isolation circuit; the second isolation circuit is a second millimeter-wave isolation circuit; the first coupling element is a first millimeter-wave antenna; and the second coupling element is a second millimeter-wave antenna.

[0033] In some other specific embodiments, the first millimeter-wave isolation circuit and the second millimeter-wave isolation circuit are integrated and packaged into a single millimeter-wave isolation chip.

[0034] In some specific embodiments, the first isolation circuit is a first magnetic coupling isolation circuit or a first capacitive coupling isolation circuit; the second isolation circuit is a second magnetic coupling isolation circuit or a second capacitive coupling isolation circuit; the first coupling element is a first magnetic coupler or a first capacitive coupler; and the second coupling element is a second magnetic coupler or a second capacitive coupler. In other words, the digital isolator of this embodiment can be applied to scenarios employing arbitrary coupling transmission methods, and its application scenarios are wide-ranging and its practicality is strong.

[0035] Specifically, the optimized matching digital isolator provided in this embodiment is a further improvement on the aforementioned digital isolator capable of transmitting anomalies, wherein the first matching network 12 and / or the second matching network 22 are specifically configured as RF transformers. For example... Figure 2 As shown, the first winding of the RF transformer is connected to the corresponding signal amplifier, the second winding is connected to the corresponding coupler, and the third winding is connected to the corresponding envelope detector.

[0036] In other words, this embodiment provides three feasible optimized matching schemes: The second matching network is configured as an RF transformer, specifically labeled as the second RF transformer.

[0037] Here, the first winding of the second RF transformer is connected to the second signal amplifier, the second winding is connected to the second coupler, and the third winding is connected to the second envelope detector.

[0038] The working principle of the second RF transformer is as follows: In normal transmission mode, after the second coupling element of the second isolation circuit receives the normal signal transmitted at high speed from the first isolation circuit, it enters the second RF transformer through the second winding connected to the second coupling element. At this time, the second winding of the second RF transformer, as the primary winding, couples the normal signal to the third winding, and outputs it to the second envelope detector connected to it. At this time, the third winding, as the secondary winding, will perform impedance matching based on the input impedance of the second envelope detector, which is the output terminal, during the coupling transmission process, so as to better and more efficiently transmit the normal signal to the second envelope detector.

[0039] When the second signal amplifier of the second isolation circuit receives an abnormal signal, it obtains the corresponding high-frequency signal through carrier modulation processing, and transmits it to the second RF transformer through the first winding connected to the second signal amplifier. At this time, the first winding of the second RF transformer acts as the primary winding, coupling the high-frequency abnormal signal to the second winding during the low-level gap of the normal signal (the above-mentioned normal transmission state proceeds as usual, and during the normal signal transmission, the first winding of the second RF transformer also acts as the secondary winding, normally receiving the normal signal sent by the second winding), and outputting it to the second coupler through the second winding. At this time, the second winding of the second RF transformer acts as the secondary winding, and impedance matching is performed based on the input impedance of the second coupler, which is the output terminal, during the coupling transmission process, so that the second coupler can transmit the high-frequency abnormal signal with maximum power.

[0040] It is understandable that the optimized matching scheme described above, particularly implemented in the second isolation circuit that typically serves as the receiver RX, is suitable for forward transmission channels with higher transmission speeds. Figure 1 The purple transmission link significantly improves the impedance matching capability of the receiver RX, maximizes the power transmission of normal signals at the receiver RX, reduces signal reflection, and improves system performance and stability.

[0041] II. The first matching network is configured as an RF transformer, specifically labeled as the first RF transformer.

[0042] Here, the first winding of the first RF transformer is connected to the first signal amplifier, the second winding is connected to the first coupler, and the third winding is connected to the first envelope detector.

[0043] The working principle of the first RF transformer is as follows: In normal transmission mode, after the first signal amplifier of the first isolation circuit receives the normal signal, it obtains the corresponding high-frequency signal through carrier modulation processing, and transmits it to the first RF transformer through the first winding connected to the first signal amplifier. At this time, the first winding of the first RF transformer acts as the primary winding, coupling the high-frequency normal signal to the second winding, and outputting it to the first coupling element through the second winding. At this time, the second winding acts as the secondary winding, and impedance matching is performed based on the input impedance of the first coupling element as the output terminal during the coupling transmission process, so that the first coupling element can transmit normally with maximum power.

[0044] When the first coupling element of the first isolation circuit receives an abnormal signal from the second coupling element, it is transmitted to the first RF transformer via the second winding connected to the first coupling element. At this time, the second winding of the first RF transformer, acting as the primary winding, couples the received abnormal signal to the third winding. Since the normal transmission state described above proceeds as usual, during the normal signal transmission period, the third winding of the first RF transformer also acts as the secondary winding and couples in the normal signal emitted by the first winding. Therefore, the signal received by the third winding of the first RF transformer will be coupled with the normal signal simultaneously transmitted from the first winding to the second winding, while the abnormal signal transmitted from the second winding of the first RF transformer will be coupled into the low-level gap of the normal signal. The third winding of the first RF transformer will output the received coupled signal to the first envelope detector connected to it. At this time, the third winding of the first RF transformer, acting as the secondary winding, will perform impedance matching based on the input impedance of the first envelope detector, which is the output terminal, during the coupling transmission process, so as to better and more efficiently transmit the coupled signal with the abnormal signal to the first envelope detector.

[0045] III. Both the first matching network and the second matching network are configured as RF transformers, and are labeled as the first RF transformer and the second RF transformer, respectively.

[0046] In this configuration, the first winding of the first RF transformer is connected to a first signal amplifier, the second winding is connected to a first coupler, and the third winding is connected to a first envelope detector. Similarly, the first winding of the second RF transformer is connected to a second signal amplifier, the second winding is connected to a second coupler, and the third winding is connected to a second envelope detector.

[0047] The working principles of the first RF transformer and the second RF transformer are as follows: In normal transmission mode, after receiving a normal signal, the first signal amplifier of the first isolation circuit obtains a corresponding high-frequency signal through carrier modulation processing. This signal is then transmitted to the first RF transformer via the first winding connected to the first signal amplifier. At this time, the first winding of the first RF transformer, acting as the primary winding, couples the high-frequency normal signal to the second winding, which then outputs it to the first coupler. The second winding, acting as the secondary winding, performs impedance matching during the coupling transmission process based on the input impedance of the first coupler (which is the output terminal), ensuring that the first coupler can transmit the normal signal at maximum power. After receiving the normal signal transmitted at high speed from the first isolation circuit, the second coupler of the second isolation circuit enters the second RF transformer via the second winding connected to the second coupler. The second winding of the second RF transformer, acting as the primary winding, couples the normal signal to its third winding, which then outputs it to the second envelope detector connected to it. The third winding, acting as the secondary winding, performs impedance matching during the coupling transmission process based on the input impedance of the second envelope detector (which is the output terminal), ensuring better and more efficient transmission of the normal signal to the second envelope detector.

[0048] When the second signal amplifier of the second isolation circuit receives an abnormal signal, it obtains the corresponding high-frequency signal through carrier modulation processing, and transmits it to the second RF transformer through the first winding connected to the second signal amplifier. At this time, the first winding of the second RF transformer acts as the primary winding, coupling the high-frequency abnormal signal to the second winding of the second RF transformer during the low-level gap of the normal signal (the above-mentioned normal transmission state proceeds as usual, and during the normal signal transmission, the first winding of the second RF transformer also acts as the secondary winding, normally receiving the normal signal sent by the second winding), and outputting it to the second coupler through the second winding. At this time, the second winding of the second RF transformer acts as the secondary winding, and impedance matching is performed based on the input impedance of the second coupler, which is the output terminal, during the coupling transmission process, so that the second coupler can transmit the high-frequency abnormal signal with maximum power. When the first coupling element of the first isolation circuit receives an abnormal signal from the second coupling element, it is transmitted to the first RF transformer via the second winding connected to the first coupling element. At this time, the second winding of the first RF transformer, acting as the primary winding, couples the received abnormal signal to the third winding. Since the normal transmission state proceeds as usual, during normal signal transmission, the third winding of the first RF transformer also acts as the secondary winding and couples in the normal signal emitted by the first winding. Therefore, the signal received by the third winding of the first RF transformer will be coupled with the normal signal simultaneously transmitted from the first winding to the second winding, while the abnormal signal transmitted from the second winding of the first RF transformer will be coupled into the low-level gap of the normal signal. The third winding of the first RF transformer will output the received coupled signal to the first envelope detector connected to it. At this time, the third winding of the first RF transformer, acting as the secondary winding, will perform impedance matching based on the input impedance of the first envelope detector, which is the output terminal, during the coupling transmission process, so as to better and more efficiently transmit the coupled signal with the abnormal signal to the first envelope detector.

[0049] The optimized matching digital isolator provided in this embodiment can specifically optimize the impedance matching capability of the matching network in the transmitting and / or receiving ends of the digital isolator with backhaul function, so as to maximize the isolated bidirectional transmission power, eliminate signal reflection, and optimize the system performance of the isolator (especially between the amplifier and the coupler).

[0050] Please see Figure 3 Another embodiment of the present invention is a further extension based on the above embodiment, and the equivalent circuit structure of the RF transformer that plays the role of optimizing matching is described.

[0051] In this embodiment, as Figure 3As shown, the RF transformer (whether it is the first RF transformer or the second RF transformer) includes two inductors (L1 and L2 in the figure), two capacitors, and an ideal transformer (within the dashed box in the figure).

[0052] In this embodiment, a capacitor is connected in parallel between the two ports of the first winding and the two ports of the second winding of the ideal transformer; an inductor is connected in parallel between the two ports of the first winding or the second winding, and an inductor is connected in series at one port. Here, the inductor connected in parallel between the two ports of the first winding or the second winding is labeled as inductor L1, and the inductor connected in series at one port of the first winding or one port of the second winding is labeled as inductor L2.

[0053] The inductor L2 is a magnetizing inductor, L2= Where Km is the coupling coefficient and Lp is the winding self-inductance, used to couple the signal from one winding to another.

[0054] The inductor L1 serves as leakage inductance, L1 = Together with the winding resistance, it constitutes the internal impedance of the RF transformer. According to the maximum power transfer theorem, the power is maximized when the load impedance matches the source impedance.

[0055] The ideal transformer is used for impedance transformation according to a turns ratio of 1:(n / Km).

[0056] It is understandable that the two inductors mentioned above are inherent, global characteristics of the RF transformer, and do not belong exclusively to any one winding of the ideal transformer. They are simply "reconstructed" and grouped onto one side of a winding for ease of analysis. That is, the RF transformer formed by placing two inductors in the first winding of the ideal transformer is completely equivalent in electrical performance to the RF transformer formed by placing two inductors in the second winding of the ideal transformer.

[0057] The RF transformer structure described in this embodiment can be regarded as a matching network of four components (two inductors, two capacitors and an ideal transformer), which has the expected matching effect, and at the same time has the advantages of simple structure and small area.

[0058] Please see Figure 4a -b and Figure 5a -b, Another embodiment of the present invention further extends the above embodiment and explains the working principle of the RF transformer.

[0059] in, Figure 4a and Figure 4b These are schematic diagrams illustrating two operating principles of a one-in-two-out RF transformer without a center tap. Figure 5a and Figure 5bThis diagram illustrates two operating principles of a one-in-two-out RF transformer with a center tap. Specifically, when using an RF transformer with a center tap, the center tap can be connected to a power supply to power the signal amplifier (PA) or buffer, provide bias voltage, or effectively suppress common-mode interference through grounding.

[0060] Please see Figure 6a -b、 Figure 7a -b、 Figure 8a -b and Figure 9 The embodiments of the present invention are further extensions based on any of the above embodiments, and specifically provide a detailed description of the connection relationship between the RF transformer and the corresponding coupler, signal amplifier and envelope detector.

[0061] In this embodiment, the output terminal of the second winding in the RF transformer can adopt a GSSG, GSGSG, or GSG layout. Regardless of the layout, the signal port S is connected to the corresponding coupler.

[0062] In some specific implementations, the envelope detector (whether it is the first envelope detector or the second envelope detector) mainly includes an ED front-end circuit and a limiting amplifier (LA); wherein, the front-end circuit can adopt a common-gate architecture or a common-source architecture. The following description will take the adoption of a common-gate architecture as an example. The limiting amplifier mainly amplifies and processes the signal output from the front-end circuit before transmitting it to the next stage.

[0063] In this embodiment, when the output terminal of the second winding of the RF transformer adopts a GSG layout, the signal port S is connected to the coupler, and the two ground ports G are grounded. The first winding of the RF transformer is connected to the output terminal of the signal amplifier, and the third winding is connected to the source of the MOS transistor in the front-end circuit of the envelope detector. The specific connection relationship is as follows: Figure 6a As shown, the blue dashed lines indicate the coupling (i.e., spatial energy transfer) relationship between the first, second, and third windings. The corresponding EM model is as follows. Figure 9 As shown, the top layer is the second winding structure, one end of the middle layer is the first winding structure, and the other end is the third winding structure.

[0064] For example, in the second isolation circuit, when the output terminal of the second winding of the second RF transformer adopts the GSG layout, the signal port S is connected to the second coupler; its first winding is connected to the output terminal of the second signal amplifier; and its third winding is connected to the source of the MOS transistor in the front-end circuit of the second envelope detector.

[0065] Accordingly, when the output terminal of the second winding of the first RF transformer in the first isolation circuit adopts the GSG layout, the signal port S is connected to the first coupler; its first winding is connected to the output terminal of the first signal amplifier, and its third winding is connected to the source of the MOS transistor in the front-end circuit of the first envelope detector.

[0066] In this embodiment, when the output terminal of the second winding of the RF transformer adopts a GSSG layout, both signal ports S are connected to couplers; the first winding of the RF transformer is connected to the output terminal of the signal amplifier, and the third winding is connected to the source of the MOS transistor in the front-end circuit of the envelope detector. The specific connection relationships are as follows: Figure 7a As shown, the blue dashed line indicates the coupling relationship between the first winding, the second winding, and the third winding.

[0067] For example, in the second isolation circuit, when the output terminal of the second winding of the second RF transformer adopts the GSSG layout, the signal port S is connected to the second coupler; its first winding is connected to the output terminal of the second signal amplifier; and its third winding is connected to the source of the MOS transistor in the front-end circuit of the second envelope detector.

[0068] Accordingly, in the first isolation circuit, when the output terminal of the second winding of the first RF transformer adopts the GSSG layout, the signal port S is connected to the first coupler; its first winding is connected to the output terminal of the first signal amplifier, and its third winding is connected to the source of the MOS transistor in the front-end circuit of the first envelope detector.

[0069] It can be understood that the GSG layout can be viewed as two independent GSG ports arranged side by side. Therefore, its connection method is the same as that of the GSSG layout described above, and the specific connection relationship is as follows: Figure 8a As shown, it will not be elaborated upon here.

[0070] In particular, when using the GSSG or GGSSG layout, the RF transformer has a center tap, which serves as a virtual ground. This does not affect the differential signal and can also be used to provide VDD voltage, bias voltage, or ground.

[0071] In some specific implementations, a capacitor is connected between the source of one MOSFET and the gate of another MOSFET in the front-end circuit of the envelope detector (whether it is the first envelope detector or the second envelope detector). This utilizes cross-coupling technology to generate a signal at the gate that is opposite to that at the source, thereby increasing the swing between the gate and source of the MOSFET and increasing the conversion gain of the envelope detector. The connection between the envelope detector structure described above, which can improve the conversion gain, and the RF transformer when using GSG, GSSG, and GGSSG layouts, respectively, is as follows. Figure 6b , Figure 7b and Figure 8b As shown.

[0072] The RF transformer provided in this embodiment can adopt a GSG, GSSG, or GGSSG layout at its output terminal connected to the coupler; it can provide the impedance required by the signal amplifier so that the signal amplifier can transmit the signal at maximum power; it can provide the impedance required by the envelope detector so that the envelope detector can receive the signal at maximum power; and it can provide the impedance required by the coupler so that the coupler can transmit / receive the signal at maximum power.

[0073] Please see Figure 1 and Figure 10 Based on any of the above embodiments, the present invention also provides an application circuit for an optimized matching digital wave isolator, including the optimized matching digital wave isolator described in any of the above embodiments; and further including a first isolated circuit 101 and a second isolated circuit 102; The first isolated circuit 101 is connected to the first isolated circuit 10; the second isolated circuit 102 is connected to the second isolated circuit 20.

[0074] Specifically, the first isolated circuit 101 is connected to the first signal amplifier 14 and the first envelope detector 13 in the first isolated circuit 10, respectively; the second isolated circuit 102 is connected to the second signal amplifier 24 and the second envelope detector 23 in the second isolated circuit 20, respectively.

[0075] This embodiment provides an application circuit for an optimized matching digital wave isolator, which can optimize the impedance matching capability of the isolation circuit in a digital isolator with feedback function, realize impedance coordination among the coupler, envelope detector and signal amplifier, eliminate signal reflection, transmit signal energy at maximum power, and improve system performance.

[0076] Please see Figure 10 The figure shows the simulated return loss curve of the optimized-matched digital wave isolator provided in the embodiments of the present invention. Figure 10It can be seen that the optimized-matching digital isolator provided in this embodiment of the invention achieves excellent impedance matching at an extremely high frequency of approximately 134 GHz. This proves that the optimized-matching digital isolator provided in this embodiment of the invention can achieve ideal impedance matching.

[0077] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An optimized matching digital isolator, characterized in that, It includes a first isolation circuit and a second isolation circuit located on both sides of the isolation strip; the first isolation circuit includes a first coupler, a first matching network, a first envelope detector, and a first signal amplifier; the second isolation circuit includes a second coupler, a second matching network, a second envelope detector, and a second signal amplifier. The first coupler, the first envelope detector, and the first signal amplifier are respectively connected to the first matching network; the second coupler, the second envelope detector, and the second signal amplifier are respectively connected to the second matching network. The second signal amplifier is configured to modulate the received abnormal signal into a high-frequency signal and then send it to the second matching network; The second matching network is configured to receive a normal signal sent from the second coupler, and to send the high-frequency signal out through the second coupler during the low-level gap of the normal signal. The first matching network is configured to receive the high-frequency signal sent by the first coupler and then couple it to the first envelope detector. The first envelope detector is configured to issue a prompt message if it can detect a high-frequency signal in a low-level gap of the coupling signal sent from the first matching network. The first matching network and / or the second matching network is an RF transformer; the RF transformer includes a first winding, a second winding and a third winding; the first winding is connected to the corresponding signal amplifier, the second winding is connected to the corresponding antenna, and the third winding is connected to the corresponding envelope detector.

2. The optimized matching digital isolator as described in claim 1, characterized in that, The second matching network is a second RF transformer; the first winding of the second RF transformer is connected to the second signal amplifier, the second winding is connected to the second coupler, and the third winding is connected to the second envelope detector.

3. The optimized matching digital isolator as described in claim 1, characterized in that, The first matching network is a first RF transformer; the first winding of the first RF transformer is connected to the first signal amplifier, the second winding is connected to the first coupler, and the third winding is connected to the first envelope detector.

4. The optimized matching digital isolator as described in claim 1, characterized in that, The first matching network is a first RF transformer, and the second matching network is a second RF transformer; The first winding of the first RF transformer is connected to the first signal amplifier, the second winding is connected to the first coupler, and the third winding is connected to the first envelope detector. The first winding of the second RF transformer is connected to the second signal amplifier, the second winding is connected to the second coupler, and the third winding is connected to the second envelope detector.

5. The optimized matching digital isolator as described in claim 1, characterized in that, One end of the second winding in the RF transformer adopts a GSSG, GSGSG, or GSG layout, and the signal port S is connected to the corresponding coupler.

6. The optimized matching digital isolator as described in claim 2, characterized in that, The front-end circuit of the second envelope detector adopts a common gate architecture; one end of the second winding of the second RF transformer adopts a GSG layout, wherein the signal port S is connected to the second coupler; the output of the second signal amplifier is connected to the first winding of the second RF transformer. In the front-end circuit of the second envelope detector, the source of the MOS transistor is connected to the third winding of the second RF transformer.

7. The optimized matching digital isolator as described in claim 2, characterized in that, The front-end circuit of the second envelope detector adopts a common gate architecture; one end of the second winding of the second RF transformer adopts a GSSG or GSGSG layout, wherein the two signal ports S are connected to the second coupler; the output terminal of the second signal amplifier is connected to the first winding of the second RF transformer; the source of the MOS transistor in the front-end circuit of the second envelope detector is connected to the third winding of the second RF transformer.

8. The optimized matching digital isolator as described in claim 6 or 7, characterized in that, In the front-end circuit of the second envelope detector, a capacitor is connected between the source of one MOS transistor and the gate of another MOS transistor.

9. The optimized matching digital isolator as described in claim 3, characterized in that, The front-end circuit of the first envelope detector adopts a common gate architecture; one end of the second winding of the first RF transformer adopts a GSG layout, wherein the signal port S is connected to the first coupler; the output terminal of the first signal amplifier is connected to the first winding of the first RF transformer; the source of the MOS transistor in the front-end circuit of the first envelope detector is connected to the third winding of the first RF transformer.

10. The optimized matching digital isolator as described in claim 3, characterized in that, The front-end circuit of the first envelope detector adopts a common gate architecture; one end of the second winding of the first RF transformer adopts a GSSG or GSGSG layout, wherein the two signal ports S are connected to the first coupler; the output terminal of the first signal amplifier is connected to the first winding of the first RF transformer; the source of the MOS transistor in the front-end circuit of the first envelope detector is connected to the third winding of the first RF transformer.

11. The optimized matching digital isolator as described in claim 9 or 10, characterized in that, A capacitor is connected between the source and the gate in the front-end circuit of the first envelope detector.

12. The optimized matching digital isolator as described in claim 1, characterized in that, The first isolation circuit is a first millimeter-wave isolation circuit; the second isolation circuit is a second millimeter-wave isolation circuit; the first coupling element is a first millimeter-wave antenna; and the second coupling element is a second millimeter-wave antenna.

13. The optimized matching digital isolator as described in claim 1, characterized in that, The first isolation circuit is a first magnetic coupling isolation circuit or a first capacitive coupling isolation circuit; the second isolation circuit is a second magnetic coupling isolation circuit or a second capacitive coupling isolation circuit; the first coupling element is a first magnetic coupler or a first capacitive coupler; the second coupling element is a second magnetic coupler or a second capacitive coupler.

14. An application circuit for an optimized matching digital wave isolator, characterized in that, Includes the optimized matching digital wave isolator as described in any one of claims 1 to 13; further includes a first isolated circuit and a second isolated circuit; The first isolated circuit is connected to the first isolated circuit; the second isolated circuit is connected to the second isolated circuit.

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