Voltage-controlled oscillator applied to millimeter wave isolator and digital isolator

Abstract

The utility model provides a voltage-controlled oscillator applied to a millimeter wave isolator, a digital isolator and a voltage-controlled oscillator. The voltage-controlled oscillator comprises an MOS tube M1, an MOS tube M2, a capacitor C1, a capacitor C2, a capacitor C3, an inductor L1 and an inductor L2. The drain electrode of the MOS tube M1 is connected with one end of a capacitor C3 and one end of an inductor L1. The drain electrode of the MOS tube M2 is connected with the other end of the capacitor C3 and the other end of the inductor L1. One end of the capacitor C1 is connected with the drain electrode of the MOS tube M1, and the other end of the capacitor C1 is connected with the grid electrode of the MOS tube M2; one end of the capacitor C2 is connected with the drain electrode of the MOS tube M2, and the other end of the capacitor C2 is connected with the grid electrode of the MOS tube M1; the inductor L1 is also connected with a power supply; the inductor L2 is coupled with the inductor L1; one end of the inductor L2 is grounded, and the other end is connected with the transmitting antenna. According to the utility model, by multiplexing the inductor L1, the use of one inductor is reduced, a considerable chip area is saved, and the chip cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of oscillators, in particular to a voltage-controlled oscillator and a digital isolator applied to a millimeter wave isolator. Background Art

[0002] Digital isolators are devices that transmit digital signals in an electrically isolated state and are widely used in industrial network environments, especially in harsh environments. Using isolators in the system can eliminate noise caused by ground return on the one hand; on the other hand, it can isolate the manually operated control port from the system execution end where there may be a high-voltage dangerous environment, thereby protecting the devices (people) on the low-voltage side from high-voltage hazards.

[0003] The latest technology in the prior art uses antenna coupling and OOK modulation mode to design an isolator, and its structure is as follows: Figure 1 shown. Figure 1 In a digital isolator with a structure of optical coupler, at the transmitting end, the signal is coupled with the carrier at the voltage-controlled oscillator VCO to form a mixed wave, which is then sent to the receiving end on the other side of the isolator through the antenna; after the receiving antenna receives the mixed wave, it amplifies the received signal through the low-noise amplifier LNA, and the demodulator module restores the mixed wave to the transmitted signal, which can easily achieve a transmission rate of hundreds of Mbps. Compared with the traditional optical coupler mode isolator, Figure 1 The isolator with the structure shown has a faster transmission speed; compared with the traditional capacitive coupling mode isolator, Figure 1 The thickness of the isolator of the structure shown can even be as thick as 1 to 2 cm. At this isolation distance, the parasitic capacitance between the two sides of the isolator can be basically ignored, so it can be considered that it will hardly be affected by common-mode transient interference; compared with the traditional magnetically coupled on-chip micro-transformer mode isolator, Figure 1 The structure shown has better isolation and almost no common-mode transient interference.

[0004] Even so, there is still room for improvement in various aspects of digital isolators designed using antenna coupling and OOK modulation mode. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a voltage-controlled oscillator and a digital isolator applied to a millimeter wave isolator, which can save the on-chip area of ​​the voltage-controlled oscillator and reduce the cost.

[0006] In order to solve the above technical problems, the first technical solution adopted by the utility model is:

[0007] A voltage-controlled oscillator applied to a millimeter wave isolator, comprising: a MOS tube M1, a MOS tube M2, a capacitor C1, a capacitor C2, a capacitor C3, an inductor L1 and an inductor L2;

[0008] The source of the MOS tube M1 and the source of the MOS tube M2 are grounded; the gate of the MOS tube M1 and the gate of the MOS tube M2 are connected; the drain of the MOS tube M1 is respectively connected to one end of the capacitor C3 and one end of the inductor L1; the drain of the MOS tube M2 is respectively connected to the other end of the capacitor C3 and the other end of the inductor L1; one end of the capacitor C1 is connected to the drain of the MOS tube M1, and the other end is connected to the gate of the MOS tube M2; one end of the capacitor C2 is connected to the drain of the MOS tube M2, and the other end is connected to the gate of the MOS tube M1;

[0009] The inductor L1 is also connected to a power supply; the inductor L2 is coupled to the inductor L1; one end of the inductor L2 is grounded, and the other end is connected to a transmitting antenna.

[0010] Optionally, a resistor R1 and a resistor R2 are further included; the gate of the MOS transistor M1 is connected to the gate of the MOS transistor M2 via the resistor R1 and the capacitor R2 connected in series.

[0011] Optionally, it also includes a variable current source and a MOS tube M3; the source of the MOS tube M3 is grounded, and the drain and the gate are respectively connected to one end of the variable current source; the other end of the variable current source is connected to a power supply; the gate of the MOS tube M3 is also connected between the resistor R1 and the resistor R2.

[0012] Optionally, it also includes a variable resistor R3 and a resistor R0; one end of the variable resistor R3 is connected to the power supply, and the other end is respectively connected to one end of the resistor R0 and the connection between the resistor R1 and the resistor R2; the other end of the resistor R0 is connected to the ground.

[0013] Optionally, it further includes a MOS tube M4 and a variable current source; the source of the MOS tube M4 is connected to the power supply, and the drain and the gate are respectively connected to one end of the variable current source; the other end of the variable current source is connected to the ground end; the gate of the MOS tube M4 is also connected between the resistor R1 and the resistor R2.

[0014] Optionally, the capacitor C3 is a variable capacitor.

[0015] Optionally, both the MOS transistor M1 and the MOS transistor M2 are N-channel MOS transistors.

[0016] The second technical solution adopted by the utility model is:

[0017] A digital isolator comprises the above-mentioned voltage-controlled oscillator applied to millimeter wave isolators.

[0018] Optionally, the transmitting antenna is a millimeter wave transmitting antenna.

[0019] The beneficial effect of the utility model is that compared with the existing voltage-controlled oscillator circuit structure used in millimeter wave isolators, the utility model can reduce the use of one inductor by reusing the inductor L1, thereby saving considerable chip area (the on-chip implementation of the inductor requires a relatively large chip area, and reducing one inductor can reduce the area on the chip by about 150um*150um), and can also reduce the chip cost to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a voltage-controlled oscillator applied to a millimeter-wave isolator in the prior art;

[0021] Figure 2 A schematic diagram of the structure of a voltage-controlled oscillator applied to a millimeter-wave isolator provided in an embodiment of the utility model;

[0022] Figure 3 (a)-(c) are schematic diagrams of three optional generating structures of the VBN starting signal of the voltage-controlled oscillator in a specific implementation manner of the utility model;

[0023] Figure 4 A schematic diagram of the overall structure of a digital isolator provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0024] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0025] Figure 1 FIG. 1 is a schematic diagram of the structure of a voltage-controlled oscillator used in a millimeter-wave isolator in the prior art. Figure 1 As shown, it includes three inductors L1-L3. Figure 1 Based on the above, by reusing the inductor L1, it is possible to reduce the use of one inductor on the chip (reducing the area by about 150um*150um), thereby reducing the chip cost to a certain extent.

[0026] See also Figure 2 , Figure 2 A schematic diagram of the structure of a voltage-controlled oscillator applied to a millimeter wave isolator provided in an embodiment of the utility model. Figure 2 As shown, the voltage-controlled oscillator applied to the millimeter wave isolator provided in this embodiment includes a MOS transistor M1, a MOS transistor M2, a capacitor C1, a capacitor C2, a capacitor C3, an inductor L1 and an inductor L2.

[0027] The source of the MOS tube M1 and the source of the MOS tube M2 are grounded; the gate of the MOS tube M1 and the gate of the MOS tube M2 are connected; the drain of the MOS tube M1 is respectively connected to one end of the capacitor C3 and one end of the inductor L1; the drain of the MOS tube M2 is respectively connected to the other end of the capacitor C3 and the other end of the inductor L1; one end of the capacitor C1 is connected to the drain of the MOS tube M1, and the other end is connected to the gate of the MOS tube M2; one end of the capacitor C2 is connected to the drain of the MOS tube M2, and the other end is connected to the gate of the MOS tube M1; one end of the capacitor C3 is used as a VOP output node, and the other end is used as a VON output node;

[0028] The inductor L1 is also connected to a power source; the inductor L2 is coupled to the inductor L1; one end of the inductor L2 is connected to a ground terminal, and the other end is connected to a transmitting antenna.

[0029] The working principle of the voltage-controlled oscillator applied to the millimeter wave isolator provided in this embodiment is as follows: the signal is coupled into the voltage-controlled oscillator at VBN, that is, between the gates of MOS tube M1 and MOS tube M2. If the VBN signal is high (logic "1"), the VBN rises, providing a DC bias for the gates of MOS tube M1 and MOS tube M2, MOS tube M1 and MOS tube M2 are turned on, and the VCO starts to oscillate; at this time, the signals at the VOP output node and the VON output node of the VCO are coupled to the inductor L2 through the inductor L1, and then sent out through the transmitting antenna, and the receiving end receives the logic "1" signal. If the input VBN signal is low (logic "0"), the VBN is 0, the MOS tube M1 and the MOS tube M2 are turned off, and the VOP / N output node no longer oscillates. At this time, the transmitting antenna does not transmit a signal, which means that the receiving end receives a logic "0" in the OOK modulation mode.

[0030] It can be seen that the voltage-controlled oscillator in this embodiment, which reduces the use of one inductor, can still ensure normal operation.

[0031] In some specific implementations of this embodiment, a resistor R1 and a resistor R2 are further included; the gate of the MOS tube M1 is connected to the gate of the MOS tube M2 via the resistor R1 and the capacitor R2 connected in series. Here, the resistor R1 and the resistor R2 are used to block the AC signal coupled to the gates of the MOS tubes M1 and M2 through the capacitors C1 and C2 after the VCO starts oscillating, so as to prevent the AC transient signal from causing serious interference to the DC signal at VBN.

[0032] In some specific implementations of this embodiment, the capacitor C3 is a variable capacitor, which can better adjust the LC resonance frequency to make it fall on the expected frequency.

[0033] In some further specific implementations of this embodiment, both the MOS transistor M1 and the MOS transistor M2 are N-channel MOS transistors.

[0034] In this embodiment, the VBN signal provides the DC level required for turning on the MOS transistor M1 and the MOS transistor M2 in the voltage-controlled oscillator. Figure 3 Three structures shown in (a)-(c) are produced.

[0035] like Figure 3 As shown in (a), a VBN signal generation structure includes a variable current source and a MOS tube M3; the source of the MOS tube M3 is grounded, and the drain and the gate are respectively connected to one end of the variable current source; the other end of the variable current source is connected to a power supply; the gate of the MOS tube M3 is also connected between the resistor R1 and the resistor R2 in the voltage-controlled oscillator, that is, at VBN.

[0036] like Figure 3 As shown in (b), another VBN signal generating structure includes a variable resistor R3 and a resistor R0; one end of the variable resistor R3 is connected to a power supply, and the other end is respectively connected to one end of the resistor R0 and to between the resistor R1 and the resistor R2 in the voltage-controlled oscillator, that is, at VBN; the other end of the resistor R0 is connected to the ground.

[0037] like Figure 3 As shown in (c), there is also a VBN signal generating structure including a MOS tube M4 and a variable current source; the source of the MOS tube M4 is connected to the power supply, and the drain and the gate are respectively connected to one end of the variable current source; the other end of the variable current source is connected to the ground end; the gate of the MOS tube M4 is also connected between the resistor R1 and the resistor R2 in the voltage-controlled oscillator, that is, at VBN.

[0038] See also Figure 4 , Figure 4 The overall structure diagram of a digital isolator provided by an embodiment of the utility model is shown in FIG. Figure 4 As shown, this embodiment also provides a digital isolator, in particular, the voltage-controlled oscillator therein is the voltage-controlled oscillator described in the above embodiment; and the transmitting antenna therein is a millimeter wave transmitting antenna. Here, the specific structure of the voltage-controlled oscillator will not be repeated, and please refer to the description of the above embodiment for details.

[0039] The digital isolator provided in this embodiment adopts millimeter wave wireless transmission technology for isolated transmission, which can not only easily achieve a transmission rate of hundreds of Mbps, but also has a faster transmission speed than the traditional optical coupling transmission method; compared with the pure capacitive coupling method, it can eliminate the influence of common mode transient interference; compared with the magnetic coupling transmission method, it greatly simplifies the process difficulty and cost. Therefore, this embodiment will have a broader and more practical application prospect in the field of wireless transmission.

[0040] At the same time, the voltage-controlled oscillator in the digital isolator provided in this embodiment is compared with Figure 1 As for the traditional voltage-controlled oscillator circuit structure, since the inductor L1 is reused, the use of one inductor can be reduced, thereby saving considerable chip area (the on-chip implementation of the inductor requires a relatively large chip area, and reducing one inductor can reduce the area on the chip by about 150um*150um), and at the same time it can also reduce the chip cost to a certain extent.

[0041] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent transformations made using the contents of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical field, are also included in the patent protection scope of the present invention.

Claims

1. A voltage-controlled oscillator for use in a millimeter wave isolator, characterized in that: include: MOS tube M1, MOS tube M2, capacitor C1, capacitor C2, capacitor C3, inductor L1 and inductor L2; The source of the MOS tube M1 and the source of the MOS tube M2 are grounded; the gate of the MOS tube M1 and the gate of the MOS tube M2 are connected; the drain of the MOS tube M1 is respectively connected to one end of the capacitor C3 and one end of the inductor L1; the drain of the MOS tube M2 is respectively connected to the other end of the capacitor C3 and the other end of the inductor L1; one end of the capacitor C1 is connected to the drain of the MOS tube M1, and the other end is connected to the gate of the MOS tube M2; one end of the capacitor C2 is connected to the drain of the MOS tube M2, and the other end is connected to the gate of the MOS tube M1; The inductor L1 is also connected to a power supply; the inductor L2 is coupled to the inductor L1; one end of the inductor L2 is grounded, and the other end is connected to a transmitting antenna.

2. The voltage-controlled oscillator for millimeter wave isolator according to claim 1, characterized in that: It also includes a resistor R1 and a resistor R2; the gate of the MOS tube M1 is connected to the gate of the MOS tube M2 via the resistor R1 and the capacitor R2 connected in series.

3. The voltage-controlled oscillator for use in a millimeter wave isolator according to claim 2, characterized in that: It also includes a variable current source and a MOS tube M3; the source of the MOS tube M3 is grounded, and the drain and the gate are respectively connected to one end of the variable current source; the other end of the variable current source is connected to a power supply; the gate of the MOS tube M3 is also connected between the resistor R1 and the resistor R2.

4. The voltage-controlled oscillator for use in a millimeter wave isolator according to claim 2, characterized in that: It also includes a variable resistor R3 and a resistor R0; one end of the variable resistor R3 is connected to the power supply, and the other end is respectively connected to one end of the resistor R0 and the connection between the resistor R1 and the resistor R2; the other end of the resistor R0 is connected to the ground.

5. The voltage-controlled oscillator for use in a millimeter wave isolator according to claim 2, characterized in that: It also includes a MOS tube M4 and a variable current source; the source of the MOS tube M4 is connected to the power supply, and the drain and the gate are respectively connected to one end of the variable current source; the other end of the variable current source is connected to the ground end; the gate of the MOS tube M4 is also connected between the resistor R1 and the resistor R2.

6. The voltage-controlled oscillator for millimeter wave isolator according to claim 1, characterized in that: The capacitor C3 is a variable capacitor.

7. The voltage-controlled oscillator for use in a millimeter wave isolator according to claim 1, characterized in that: The MOS transistor M1 and the MOS transistor M2 are both N-channel MOS transistors.

8. A digital isolator, characterized in that: A voltage-controlled oscillator applied to a millimeter wave isolator comprising the voltage-controlled oscillator as described in any one of claims 1 to 7.

9. The digital isolator according to claim 8, characterized in that The transmitting antenna is a millimeter wave transmitting antenna.

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