Digital isolator and data transmission device

Abstract

Disclosed in the present invention is a digital isolator, comprising a modulator, a voltage-controlled oscillator, and an antenna. A baseband signal is input to the modulator; the voltage-controlled oscillator outputs the baseband signal to the antenna; the voltage-controlled oscillator comprises a variable capacitor and two transistors; the variable capacitor is connected between gates of the two transistors; and the output of the modulator controls the change of the capacitance value of the variable capacitor. The baseband signal controls the capacitance value of the variable capacitor by means of the modulator, so that the output frequency of the voltage-controlled oscillator is changed, achieving the objective of modulating a signal. By using the modulation, three or more signal changes can be realized, so that the digital isolator can be used for a USB3.0 protocol. Moreover, the digital isolator of the present invention simply needs an active component, i.e., the voltage-controlled oscillator, and thus has a low energy consumption ratio. Further disclosed in the present invention is a data transmission device comprising the digital isolator.

Description

A digital isolator and a data transmission device Technical Field

[0001] The present invention relates to the technical field of data transmission, and in particular to a digital isolator and a data transmission device. Background Art

[0002] Existing digital isolators typically use OOK or ASK mixing. Their transmitter (TX) requires at least a voltage-controlled oscillator (VCO) and a buffer or power amplifier (PA), as shown in Figure 1. A baseband (BB) signal is modulated by a modulator, turning the buffer or PA on or off to achieve mixing. However, this method only has two modes: on or off, making it applicable only to USB 2.0 and not USB 3.0. Furthermore, this method requires at least two active components—the VCO and the buffer or PA—and thus suffers from low energy efficiency. Using only a single existing VCO to implement OOK or ASK modulation reduces power consumption, but is still only suitable for USB 2.0. The VCO's startup time limits its speed, making it unsuitable for USB 2.0. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is that the existing digital isolators have low energy consumption ratio and are not applicable to USB 3.0.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A digital isolator includes a modulator, a voltage-controlled oscillator, and an antenna. A baseband signal is input to the modulator, and the voltage-controlled oscillator outputs to the antenna. The voltage-controlled oscillator includes a variable capacitor and two transistors. The variable capacitor is connected between the gates of the two transistors. The output of the modulator controls the variable capacitor to change its capacitance value.

[0006] Another technical solution adopted in the present invention is:

[0007] A data transmission device includes the above-mentioned digital isolator.

[0008] The present invention provides the following advantages: a baseband signal controls the capacitance of a variable capacitor via a modulator, thereby varying the output frequency of a voltage-controlled oscillator, thereby achieving signal modulation. This modulation scheme can achieve three or more signal variations, making it applicable to the USB 3.0 protocol. Furthermore, the digital isolator of the present invention requires only one active component, the voltage-controlled oscillator, resulting in low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG1 is a system diagram of a digital isolator in the prior art;

[0010] FIG2 is a system diagram of a digital isolator according to an embodiment of the present invention;

[0011] FIG3 is a schematic diagram showing a chip structure in which a voltage-controlled oscillator and an antenna of a digital isolator according to an embodiment of the present invention are integrated into the same chip;

[0012] FIG4 is a circuit diagram of a digital isolator according to an embodiment of the present invention;

[0013] FIG5 is a schematic diagram of a capacitor array according to an embodiment of the present invention;

[0014] FIG6 is a schematic diagram showing the relationship between the capacitance value after adjustment of the capacitor array shown in FIG5 and the number of fixed capacitors connected;

[0015] FIG7 is a schematic diagram showing the relationship between the output power and frequency of a voltage-controlled oscillator according to an embodiment of the present invention;

[0016] FIG8 is another circuit diagram of the digital isolator according to the embodiment of the present invention.

[0017] Explanation of reference numerals: 1. Modulator; 2. Voltage-controlled oscillator; 3. Antenna; 4. Substrate. DETAILED DESCRIPTION

[0018] In order to more clearly understand the technical content, achieved purposes and effects of the present invention, the present invention is described in detail below in conjunction with specific embodiments and in conjunction with the accompanying drawings. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] Please refer to Figures 2-8 for the technical solution provided by the present invention:

[0020] A digital isolator includes a modulator, a voltage-controlled oscillator, and an antenna. A baseband signal is input to the modulator, which outputs the signal to the antenna. The voltage-controlled oscillator includes a variable capacitor and two transistors, with the variable capacitor connected between the gates of the two transistors. The modulator's output controls the variable capacitor to change its capacitance. This digital isolator can be used with the USB 3.0 protocol and has the advantage of low power consumption.

[0021] Optionally, the variable capacitor is composed of a plurality of fixed capacitors connected in parallel, each fixed capacitor is connected in series with a switch, and the output of the modulator controls the opening and closing of the switch.

[0022] In the digital isolator of the present invention, the variable capacitor can be a capacitor with adjustable capacitance value, or a fixed capacitor array. The present invention preferably adopts the form of a fixed capacitor array. Figure 5 is a schematic diagram of a fixed capacitor array, and Figure 6 is a schematic diagram of the relationship between the adjusted capacitance value and the number of fixed capacitors connected when using this capacitor array. Figure 7 is a schematic diagram of the relationship between the output power and frequency of the voltage-controlled oscillator. As can be seen from the figure, the modulation can be more than two variations (e.g., three variations are possible), so it can be used in the USB 3.0 protocol.

[0023] Optionally, the antenna is an active antenna.

[0024] Optionally, the antenna is a differential antenna.

[0025] The digital isolator of the present invention uses an active antenna. By adjusting the active antenna to match the impedance of the voltage-controlled oscillator, there is no need to design a dedicated matching network for the voltage-controlled oscillator. The differential antenna architecture also effectively suppresses common-mode interference.

[0026] Optionally, the drains of the two transistors are respectively connected to the two transmission lines of the antenna.

[0027] Optionally, the voltage-controlled oscillator and the antenna are integrated into the same chip.

[0028] To increase bandwidth and data rate, millimeter-wave digital isolators will develop towards higher frequencies. Integrating the voltage-controlled oscillator and antenna into the same chip can make the components smaller, making them suitable for higher-frequency digital isolator structures.

[0029] Optionally, the chip includes a substrate, the voltage-controlled oscillator and the antenna are arranged on the substrate, the transmission line of the antenna extends to one side, the voltage-controlled oscillator is arranged on the side where the antenna transmission line extends and is connected to the transmission line of the antenna, and a power supply terminal and two ground terminals are provided on the side of the antenna away from the voltage-controlled oscillator, the power supply terminal of the antenna is connected to the power supply terminal, and the two ground terminals are symmetrically distributed on both sides of the power supply terminal and there is a gap between them.

[0030] The above is a specific structure in which the antenna and the voltage-controlled oscillator are integrated into the same chip. This structure is a slotted dipole antenna that can provide the inductance required by the voltage-controlled oscillator. The impedance can be adjusted according to the needs of the voltage-controlled oscillator.

[0031] Optionally, the transistors are NMOS transistors, the sources of the two transistors are grounded, the drains of the two transistors are connected to the power supply, a capacitor is connected between the gate of one transistor and the drain of the other transistor, two resistors are connected in series between the gates of the two transistors, and the drains of the two transistors are also connected to the antenna.

[0032] Compared to antennas placed in the package, the antenna and voltage-controlled oscillator are integrated into the same chip. From the active circuit side, it is an inductive element. Therefore, the drains of the two transistors do not need to be connected to an inductor and can be directly connected to the power supply.

[0033] Optionally, the transistors are NMOS transistors, the sources of the two transistors are grounded, the drains of the two transistors are connected to the power supply through an inductor, a capacitor is connected between the gate of one transistor and the drain of the other transistor, two resistors are connected in series between the gates of the two transistors, and the drains of the two transistors are also connected to the antenna.

[0034] Another technical solution provided by the present invention is:

[0035] A data transmission device includes the above-mentioned digital isolator.

[0036] Please refer to FIG2 , the first embodiment of the present invention is:

[0037] A digital isolator includes a modulator 1, a voltage-controlled oscillator 2, and an active differential antenna 3. A baseband signal is input to the modulator 1, and the voltage-controlled oscillator 2 outputs the signal to the antenna 3. The voltage-controlled oscillator 2 includes a variable capacitor and two transistors. The variable capacitor is connected between the gates of the two transistors. The output of the modulator 1 controls the capacitance of the variable capacitor to change its value.

[0038] Referring to Figures 2 and 3, the second embodiment of the present invention is as follows:

[0039] A digital isolator is different from the first embodiment in that the voltage-controlled oscillator 2 and the antenna 3 are integrated into the same chip.

[0040] The chip includes a substrate 4, on which the voltage-controlled oscillator 2 and antenna 3 are mounted. The transmission line of the antenna 3 extends to one side, and the voltage-controlled oscillator 2 is located on the side where the transmission line of the antenna 3 extends and is connected to the transmission line of the antenna 3. A power supply terminal VDD and two ground terminals GND are provided on the side of the antenna 3 away from the voltage-controlled oscillator 2. The power supply terminal of the antenna 3 is connected to the power supply terminal VDD, and the two ground terminals GND are symmetrically distributed on both sides of the power supply terminal VDD and have a gap between them. This is shown in Figure 3.

[0041] 2, 4-7, the third embodiment of the present invention is:

[0042] A digital isolator includes a modulator 1, a voltage-controlled oscillator 2, and an antenna 3, wherein the antenna 3 is an active differential antenna.

[0043] The voltage controlled oscillator 2 includes a first NMOS transistor M1, a second NMOS transistor M2, a variable capacitor C t , two capacitors C b , two resistors R b and an inductor L. A variable capacitor C is connected between the gate of the first NMOS transistor M1 and the gate of the second NMOS transistor M2. b The gate of the first NMOS transistor M1 is connected to a resistor R b One end of the second NMOS transistor M2 is connected to the gate of another resistor R b One end of the two resistors R b A capacitor C is connected between the gate of the first NMOS transistor M1 and the drain of the second NMOS transistor M2, and between the gate of the second NMOS transistor M2 and the drain of the first NMOS transistor M1. b The drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 are connected to a power supply via an inductor L. The source of the first NMOS transistor M1 and the source of the second NMOS transistor M2 are both grounded. In another embodiment, the inductor L can be replaced by two inductors, with the drain of the first NMOS transistor M1 connected to one end of one inductor, the drain of the second NMOS transistor M2 connected to one end of the other inductor, and the other ends of the two inductors connected to a power supply.

[0044] The drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 are connected to the two transmission lines of the antenna 3 respectively. The baseband signal is input to the modulator 1, and the output of the modulator 1 controls the variable capacitor C t Change the capacitor value, as shown in Figure 4.

[0045] In one embodiment, the variable capacitor C tThis is a capacitor array consisting of multiple fixed capacitors connected in parallel with switches in series. The modulator output is connected to the switches, and the final capacitance value is changed by controlling the opening and closing of the switches. As shown in Figure 5, the arrows indicate the transmission direction of the modulator's output signal. Figure 6 shows a schematic diagram of the relationship between the adjusted capacitance value and the number of fixed capacitors connected. Figure 7 shows a schematic diagram of the relationship between the output power and frequency of a voltage-controlled oscillator.

[0046] Please refer to Figures 2, 3 and 8, the fourth embodiment of the present invention is:

[0047] A digital isolator includes a modulator 1, a voltage-controlled oscillator 2, and an antenna 3, wherein the antenna 3 is an active differential antenna. The voltage-controlled oscillator 2 and the antenna 3 are integrated into the same chip.

[0048] The voltage controlled oscillator 2 includes a first NMOS transistor M1, a second NMOS transistor M2, a variable capacitor C t , two capacitors C b And two resistors R b A variable capacitor C is connected between the gate of the first NMOS transistor M1 and the gate of the second NMOS transistor M2. b The gate of the first NMOS transistor M1 is connected to a resistor R b One end of the second NMOS transistor M2 is connected to the gate of another resistor R b One end of the two resistors R b A capacitor C is connected between the gate of the first NMOS transistor M1 and the drain of the second NMOS transistor M2, and between the gate of the second NMOS transistor M2 and the drain of the first NMOS transistor M1. b The drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 are both connected to a power supply. The source of the first NMOS transistor M1 and the source of the second NMOS transistor M2 are both grounded.

[0049] The drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 are connected to the two transmission lines of the antenna 3 respectively. The baseband signal is input to the modulator 1, and the output of the modulator 1 controls the variable capacitor C t Change the capacitor value, as shown in Figure 8.

[0050] In the digital isolator of this embodiment, since the voltage-controlled oscillator and the antenna are integrated into the same chip rather than being provided on the package, an inductive element is used from the active circuit side. This element can replace the inductor connected to the drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 in the third embodiment. Therefore, in this embodiment, the drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 are directly connected to the power supply.

[0051] The variable capacitor of this embodiment may be a variable capacitor with adjustable capacitance, or may be a capacitor array as described in the third embodiment.

[0052] The chip structure in which the voltage controlled oscillator and the antenna are integrated into the same chip in this embodiment may be as described in Embodiment 2. The voltage controlled oscillator and the antenna are connected to a power supply via the power supply terminal and are grounded via the ground terminal.

[0053] The fifth embodiment of the present invention is:

[0054] A data transmission device includes the digital isolator of the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment.

[0055] In summary, the digital isolator and data transmission device provided by the present invention can implement modulation of various signal changes and is suitable for the USB 3.0 protocol. It does not require a matching network for the voltage-controlled oscillator and can effectively suppress common-mode interference. The voltage-controlled oscillator and antenna are integrated into the same chip, which is suitable for higher frequency requirements and can save inductance.

[0056] It should be noted that the connections described in the present invention all refer to electrical connections.

[0057] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Therefore, any modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A digital isolator comprising a modulator, a voltage-controlled oscillator, and an antenna, wherein a baseband signal is input to the modulator, wherein: The voltage controlled oscillator outputs to the antenna. The voltage controlled oscillator includes a variable capacitor and two transistors. The variable capacitor is connected between the gates of the two transistors. The output of the modulator controls the variable capacitor to change its capacitance value.

2. The digital isolator according to claim 1, wherein: The variable capacitor is composed of a plurality of fixed capacitors connected in parallel, each fixed capacitor is connected in series with a switch, and the output of the modulator controls the opening and closing of the switch.

3. The digital isolator according to claim 1, wherein: The antenna is an active antenna.

4. The digital isolator according to claim 3, wherein: The antenna is a differential antenna.

5. The digital isolator according to claim 4, wherein: The drains of the two transistors are respectively connected to the two transmission lines of the antenna.

6. The digital isolator according to claim 1, wherein: The voltage-controlled oscillator and the antenna are integrated into the same chip.

7. The digital isolator according to claim 6, wherein: The chip includes a substrate, the voltage-controlled oscillator and the antenna are arranged on the substrate, the transmission line of the antenna extends to one side, the voltage-controlled oscillator is arranged on the side where the antenna transmission line extends and is connected to the transmission line of the antenna, and a power supply terminal and two ground terminals are provided on the side of the antenna away from the voltage-controlled oscillator, the power supply terminal of the antenna is connected to the power supply terminal, and the two ground terminals are symmetrically distributed on both sides of the power supply terminal and there is a gap between them.

8. The digital isolator according to claim 6, wherein: The transistors are NMOS transistors, the sources of the two transistors are grounded, the drains of the two transistors are connected to a power supply, a capacitor is connected between the gate of one transistor and the drain of the other transistor, two resistors are connected in series between the gates of the two transistors, and the drains of the two transistors are also connected to an antenna.

9. The digital isolator according to claim 1, wherein: The transistors are NMOS transistors, the sources of the two transistors are grounded, the drains of the two transistors are connected to the power supply through an inductor, a capacitor is connected between the gate of one transistor and the drain of the other transistor, two resistors are connected in series between the gates of the two transistors, and the drains of the two transistors are also connected to the antenna.

10. A data transmission device, characterized in that: The digital isolator comprises the digital isolator described in any one of claims 1 to 9.

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