WO2023045604A1 - 一种滤波装置、滤波器件和传输装置 - Google Patents

一种滤波装置、滤波器件和传输装置 Download PDF

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WO2023045604A1
WO2023045604A1 PCT/CN2022/111503 CN2022111503W WO2023045604A1 WO 2023045604 A1 WO2023045604 A1 WO 2023045604A1 CN 2022111503 W CN2022111503 W CN 2022111503W WO 2023045604 A1 WO2023045604 A1 WO 2023045604A1
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Prior art keywords
differential
common
mode
circuit
signal
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PCT/CN2022/111503
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English (en)
French (fr)
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陈继良
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尹伟明
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Priority to JP2024542228A priority Critical patent/JP2024535636A/ja
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/06—Frequency selective two-port networks including resistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks

Definitions

  • This application relates to electronic circuit systems, mainly to filter devices, filter devices and transmission devices for differential circuits.
  • Serial bus technology is used in many standards, such as: universal serial bus, high-speed serial computer expansion bus standard, Ethernet, vehicle Ethernet, low voltage differential signal, high-definition multimedia interface.
  • the differential transmission mode refers to a communication mode in which data is transmitted using differential signals of opposite phases (also called differential mode signals).
  • the receiving device reads the serial data based on the difference between the two differential signals. Differential signals are conducive to further high-speed signal transmission.
  • Differential signaling helps reduce electromagnetic interference. Because the paths for transmitting differential signals are parallel, and the AC parts of ideal differential signals are equal in size and opposite in direction, so most of the electromagnetic fields they radiate to the outside cancel each other out, so the electromagnetic radiation energy is low. Moreover, when there is spatial electromagnetic energy transmitted to the differential transmission path, noise often enters the transmission path in the form of common-mode noise (also called common-mode signal) due to the parallel arrangement of differential signal cables. The differential signal receiver can reject common-mode noise interference within the tolerance range of the received level of the signal. Therefore, the differential signal transmission data has a certain inhibitory effect on external common mode noise.
  • common-mode noise also called common-mode signal
  • the signal sent by the differential signal transmitting circuit always contains common-mode noise components due to various reasons; and for the differential receiving circuit, when the common-mode noise exceeds its common-mode noise tolerance In the future, the received data will be lost, and even the receiving circuit will be damaged.
  • a filter circuit for common-mode noise needs to be added to the circuit.
  • the filter circuit includes a common-mode inductor, also known as a common-mode choke.
  • common mode inductors can reduce the common mode current in signal transmission.
  • the common-mode inductor suppresses the common-mode noise level input from the outside within the allowable range of the receiver.
  • circuits in Fig. 1A, Fig. 1B and Fig. 1C are used in the disclosed filters.
  • Fig. 1A shows a disclosed filter circuit one, the filter circuit is a common-mode inductor, and the effect of the common-mode inductor is to increase the common-mode current impedance of the line
  • impedance in this article means devices such as resistors, capacitors, and inductors or signal lines
  • the ability to limit the flow of current is not only caused by the resistance of the device or line itself, but also may be caused by the inductance, capacitance and other factors of the device or line itself, or by a combination of these factors cause.), thereby reducing the common-mode current on the line.
  • the disadvantage of this circuit is that control of the common-mode current relies on the common-mode impedance of a single common-mode inductor.
  • FIG. 1B shows a second disclosed filter circuit, in which a common-mode inductor is connected in parallel with a differential-mode inductor (also called a differential-mode choke coil or a normal-mode choke coil).
  • a common-mode inductor also called a differential-mode choke coil or a normal-mode choke coil.
  • the function of the common-mode inductor is the same as that in FIG. 1A
  • the function of the differential-mode inductor is to shunt the common-mode current and perform impedance matching on the common-mode signal.
  • This circuit has the following disadvantages:
  • the common-mode impedance of the differential-mode inductor is designed to be equal or similar to the common-mode impedance of the signal line, which is used to absorb the common-mode signal reflected by the common-mode choke coil.
  • This design causes the frequency range of the filter to be too narrow.
  • the common-mode signal reflected by the common-mode inductor is absorbed by the differential-mode inductor, the common-mode signal introduced by the differential signal drive circuit or the differential cable will still reach the common-mode signal along the signal line path. Die inductance. Moreover, the attenuation of this part of the common-mode signal is not obvious.
  • FIG. 1C shows the third disclosed filter circuit.
  • a differential mode inductor is connected in parallel on the left and right sides of a common mode inductor, wherein each differential mode inductor controls the common mode signal on both sides of the common mode choke coil. shunt.
  • the disadvantages of this circuit are:
  • embodiments of the present application provide a filtering device, a filtering device, and a transmission device.
  • the filter device passes through the filter circuit of the common-mode signal combined with the common-mode inductance and the differential-mode inductance connected in sequence, in the broadband range, the differential-mode signal will not be overly attenuated, and the differential-mode signal (for comparison, the The differential signal is expressed as a differential mode signal, and the common mode noise is called a common mode signal)
  • the common mode signal in the transmission direction realizes multi-stage cascade attenuation, and the attenuation effect is good.
  • multi-stage cascade attenuation is also implemented for the common-mode signal coupled in from the receiving end to protect the device at the sending end of the differential signal.
  • the embodiment of the present application provides a filter device for filtering common-mode signals of differential lines
  • the filter device includes: at least two common-mode inductors and at least one differential-mode inductor;
  • the common-mode inductor has two coils The choke coil, and the magnetic flux generated by the two coils of each common-mode inductor when the common-mode signal flows through them strengthens each other, wherein, one coil of the common-mode inductor is connected in series in a branch of the differential line, each common-mode inductor The other coil of the differential mode inductor is connected in series on the other branch of the differential line in sequence;
  • the differential mode inductor is a choke coil with two coils, and the magnetic flux generated by the two coils of each differential mode inductor flows through the common mode signal mutually Cancellation, wherein one of the two coils of a differential mode inductor is respectively connected between two branches of the differential line between adjacent common mode inductors and the ground.
  • a multi-stage cascaded filtering device composed of at least two common-mode inductors in series and a differential-mode inductor in parallel with each two common-mode inductors is used to perform multi-stage attenuation on the common-mode signal sent from the differential signal transmission circuit,
  • the signal-to-noise ratio of the differential line signal is better improved;
  • multi-level attenuation is also performed on the common-mode signal introduced from the load of the differential signal and introduced during the transmission process, and the attenuation effect is better. , to protect the differential signal transmission circuit.
  • the plane noise and the common-mode signal coupled on the cable can also be filtered in multiple stages to further improve the signal-to-noise ratio of the differential line signal, and the common-mode signal can be cascaded to further reduce the noise on the data cable. Noise radiates outward.
  • the filter device further includes: a differential mode inductor connected between the input end of the filter device and ground, wherein the two coils of the differential mode inductor are respectively connected to Between the two branches of the differential line at the input end of the filtering device and the ground.
  • a differential mode inductor connected between the input terminal of the filter device and the ground is used to match the impedance between the filter device and the differential signal output circuit.
  • the filter device further includes: a differential mode inductor connected between the output terminal of the filter device and the ground, wherein the two coils of the differential mode inductor are respectively connected to Between the two branches of the differential line at the output of the filtering device and ground.
  • a differential mode inductor connected between the output end of the filter device and the ground is used to match the impedance between the filter device and the load line of the differential signal.
  • the filter device further includes: a diode respectively connected between the two branches of the differential line at the input end of the filter device and the ground, and the diode can be unidirectional or bidirectional diode.
  • a diode connected between the two branches of the differential line at the input end of the filter device and the ground realizes the input limit and anti-static of the filter device.
  • the filter device further includes: a diode respectively connected between the two branches of the differential line at the output end of the filter device and the ground, and the diode can be unidirectional or bidirectional diode.
  • the filtering device further includes: a third circuit in which two branches of the differential line at the input end of the filtering device are respectively connected in series, and the third circuit includes at least one of the following: Inductors, resistors, capacitors, diodes.
  • the optimal solution of the third circuit is a capacitor.
  • the two branches of the differential line at the input end of the filtering device are respectively connected in series with a circuit composed of at least one of inductors, resistors, capacitors, and diodes to match or isolate the DC signal in the input signal.
  • the filter device further includes: the third circuit connected in series with two branches of the differential line at the output end of the filter device.
  • the two branches of the differential line at the output end of the filtering device are respectively connected in series with a circuit composed of at least one of inductors, resistors, capacitors, and diodes to match or isolate the DC signal in the output signal.
  • a fourth circuit is further connected between the ground terminals of the two coils of each differential mode inductor and the ground, and the fourth circuit includes at least one of the following: inductors, resistors, capacitors, diode.
  • the optimal solution of the fourth circuit is a capacitor.
  • a circuit composed of at least one of the inductor, resistor, capacitor, and diode is connected in series between the ground terminal of the two coils of each differential mode inductor and the ground to realize the DC signal between the filter device and the ground.
  • Matching or isolation is to achieve matching or isolation between the ground of the upper differential signal output circuit and the ground of the lower differential signal load circuit.
  • the ground ends of the two coils of several differential mode inductors are combined.
  • the circuit of the filtering device is simplified by combining the ground terminals of the two coils of several differential mode inductors. If the fourth circuit is grounded after the combination, the amount of the fourth circuit is reduced, and the circuit of the filtering device is simplified.
  • the embodiment of the present application provides a filter device for filtering common-mode signals of differential lines
  • the filter device includes: at least two common-mode inductors and at least one first circuit, wherein the common-mode inductor has two A choke coil of two coils, and the magnetic flux generated by the two coils of each common mode inductor when the common mode signal flows through them strengthens each other
  • the first circuit includes two second circuits
  • the second circuit is a capacitor or a capacitor and a resistor.
  • a series circuit wherein one coil of the common mode inductor is serially connected in series on one branch of the differential line, and the other coil of each common mode inductor is serially connected in series on the other branch of the differential line; in the adjacent common mode A second circuit is respectively connected between the two branches of the differential line between the inductors and the ground.
  • the filtering device can attenuate the common-mode signal sent from the differential signal transmission circuit in multiple stages and has a combination effect, and has little influence on the differential-mode signal, and can better improve the differential line signal in a wider bandwidth.
  • Signal-to-noise ratio at the same time, multi-level and combined effect attenuation is performed on the common-mode signal introduced from the load of the differential signal and the transmission process. The attenuation effect is good and the differential signal transmission circuit is protected.
  • multi-stage filtering can also be performed on the plane noise and the common-mode signal coupled through the cable to further improve the signal-to-noise ratio of the differential line signal, and further reduce the noise on the data cable by cascading to reduce each common-mode signal Radiate outward.
  • the filter device further includes: one second circuit respectively connected between the two branches of the differential line at the input end of the filter device and the ground.
  • the filter device further includes: one second circuit respectively connected between the two branches of the differential line at the output end of the filter device and the ground.
  • the filter device further includes: a diode respectively connected between the two branches of the differential line at the input end of the filter device and the ground, and the diode is unidirectional or bidirectional diode.
  • a diode connected between the two branches of the differential line at the input end of the filter device and the ground realizes the input limit and anti-static of the filter device.
  • the filter device further includes: a diode respectively connected between the two branches of the differential line at the output end of the filter device and the ground, and the diode is unidirectional or bidirectional diodes.
  • the embodiment of the present application further provides a filtering device, including the filtering device in the first aspect of the embodiment of the present application or the filtering device in the second aspect of the embodiment of the present application.
  • the filtering device of the first aspect of the embodiment of the present application or the filtering device of the second aspect of the embodiment of the present application are packaged in one device to generate a multi-stage cascaded filtering device for common mode signals, and
  • the common mode signal sent from the differential signal transmission circuit is multi-stage attenuated, and has little influence on the differential mode signal, and the signal-to-noise ratio of the differential line signal is improved in a wide bandwidth; at the same time, the signal from the differential signal
  • the common mode signal introduced by the load and the transmission process also performs multi-stage attenuation, the attenuation effect is good, and the differential signal transmission circuit is protected.
  • multi-stage filtering can also be performed on the plane noise and the common-mode signal coupled through the cable to further improve the signal-to-noise ratio of the differential line signal, and further reduce the noise on the data cable by cascading to reduce each common-mode signal Radiate outward.
  • the filtering device when the filtering device includes the filtering device of the first aspect of the embodiments of the present application, the filtering device includes the filtering device of the first aspect of the embodiments of the present application Any possible implementation of the device.
  • any possible implementation of the filtering device in the first aspect of the embodiment of the present application is packaged in one device to realize the functions corresponding to each possible implementation of the filtering device in the first aspect of the embodiment of the present application .
  • the filtering device when the filtering device includes the filtering device of the second aspect of the embodiments of the present application, the filter further includes the filtering device of the second aspect of the embodiments of the present application. Any possible implementation of the filtering device.
  • any possible implementation of the filtering device in the second aspect of the embodiment of the present application is packaged in one device, and each possible implementation of the filtering device in the second aspect of the embodiment of the present application is realized. Function.
  • the embodiment of the present application further provides a filter device, including: a device that encapsulates the common mode inductors in the first aspect of the embodiment of the present application or any possible implementation of the first aspect, and the embodiment of the present application Other circuits in the first aspect or any possible implementation manner of the first aspect.
  • the fourth aspect of the embodiment of the present application has the advantages of the first aspect of the embodiment of the present application or any possible implementation manner of the first aspect.
  • the embodiment of the present application further provides a filter device, including: a device that encapsulates the common mode inductors in the second aspect of the embodiment of the present application or any possible implementation of the second aspect, and the embodiment of the present application Other circuits in the second aspect or any possible implementation manner of the second aspect.
  • the fifth aspect of the embodiment of the present application has the advantages of the second aspect of the embodiment of the present application or any possible implementation manner of the second aspect.
  • the embodiment of the present application also provides a transmission device, including: a differential cable; both ends of the differential cable are connected to one of the following devices or devices:
  • the filtering device
  • the transmission device includes a filter device or filter device for multi-stage cascaded filtering of the common-mode signal, which realizes multi-stage attenuation of the common-mode signal sent from the differential signal transmission circuit, and has little influence on the differential-mode signal.
  • the signal-to-noise ratio of the differential line signal is better improved; at the same time, multi-stage attenuation is also performed on the common-mode signal introduced from the differential signal receiving circuit and the transmission process, and the attenuation effect is better, protecting the Differential signal transmission circuit.
  • multi-stage filtering can also be performed on the plane noise and the common-mode signal coupled on the cable to improve the signal-to-noise ratio of the differential line signal, and reduce the common-mode signal on each data cable by cascading to reduce noise Radiate outward.
  • any of the following connection methods is included between the shielded wires at both ends of the differential cable and the ground: no connection; connection through inductance; connection through magnetic beads.
  • FIG. 1A is a schematic diagram of a disclosed filter circuit 1
  • FIG. 1B is a schematic diagram of a disclosed filter circuit 2
  • FIG. 1C is a schematic diagram of the disclosed filter circuit 3
  • FIG. 2 is a schematic structural diagram of traditional application scenarios of various embodiments of the present application.
  • FIG. 3A is a schematic structural diagram of Embodiment 1 of a filter device of the present application.
  • FIG. 3B1 is a schematic diagram of the effect analysis of a practical application of Embodiment 1 of a filter device of the present application;
  • FIG. 3B2 is a schematic diagram of another practical application effect analysis of Embodiment 1 of a filter device of the present application.
  • FIG. 3C1 is a schematic structural diagram of a specific implementation of Embodiment 1 of a filter device of the present application.
  • FIG. 3C2 is a schematic diagram of the absolute value of the common-mode impedance and the absolute value of the differential-mode impedance of a common-mode inductor changing with frequency;
  • FIG. 3C3 is a schematic diagram of a filtering effect of a specific implementation of Embodiment 1 of a filtering device of the present application;
  • FIG. 3C4 is a schematic diagram of the filtering effect of the disclosed filtering circuit 2;
  • FIG. 3C5 is a schematic diagram of the filtering effect of the disclosed filtering circuit 3;
  • FIG. 4A is a schematic structural diagram of Embodiment 2 of a filter device of the present application.
  • Fig. 4B1 is a schematic diagram of the effect analysis of a practical application of a filter device embodiment 2 of the present application;
  • FIG. 4B2 is a schematic diagram of another practical application effect analysis of Embodiment 2 of a filter device of the present application.
  • FIG. 4C is a schematic structural diagram of a specific implementation of Embodiment 2 of a filtering device of the present application.
  • FIG. 5A1 is a schematic structural diagram of Variation 1 of Embodiment 2 of a filtering device of the present application;
  • FIG. 5A2 is a schematic structural diagram of Variation 2 of Embodiment 2 of a filter device of the present application.
  • FIG. 5A3 is a schematic structural diagram of Variation 3 of Embodiment 2 of a filter device of the present application.
  • FIG. 5B1 is a schematic structural diagram of Variation 4 of Embodiment 2 of a filter device of the present application.
  • FIG. 5B2 is a schematic structural diagram of Variation 5 of Embodiment 2 of a filter device of the present application.
  • FIG. 5C1 is a schematic structural diagram of Variation 6 of Embodiment 2 of a filtering device of the present application.
  • FIG. 5C2 is a schematic structural diagram of Variation 7 of Embodiment 2 of a filter device of the present application.
  • FIG. 5D1 is a schematic structural diagram of Variation 8 of Embodiment 2 of a filter device of the present application.
  • FIG. 5D2 is a schematic structural diagram of Variation 9 of Embodiment 2 of a filter device of the present application.
  • FIG. 5D3 is a schematic structural diagram of Variation 10 of Embodiment 2 of a filtering device of the present application.
  • FIG. 5D4 is a schematic structural diagram of Variation 11 of Embodiment 2 of a filter device of the present application.
  • FIG. 5E is a schematic diagram of the circuit structure of the combination of Variation 1 to Variation 7 of Embodiment 2 of a filter device of the present application;
  • FIG. 6A is a schematic diagram of a circuit structure of Embodiment 3 of a filter device of the present application.
  • FIG. 6B is a schematic diagram of the attenuation value of the first common-mode signal in Embodiment 3 of a filter device of the present application;
  • FIG. 6C is a schematic diagram of the attenuation value of the differential mode signal in the third embodiment of a filter device of the present application.
  • FIG. 7 is a schematic diagram of a circuit structure of Embodiment 4 of a filtering device of the present application.
  • FIG. 8 is a schematic circuit structure diagram of a combination of Variation 1 to Variation 5 of Embodiment 4 of a filter device of the present application;
  • FIG. 9A1 is a schematic diagram of the internal circuit structure of a device embodiment 1 of the present application.
  • FIG. 9A2 is a schematic diagram of the internal circuit structure of a second device embodiment of the present application.
  • FIG. 9B1 is a schematic diagram of the internal circuit structure of a third device embodiment of the present application.
  • FIG. 9B2 is a schematic diagram of the internal circuit structure of Embodiment 4 of a device of the present application.
  • FIG. 9C1 is a circuit structure diagram of a combination of variants 1 to 7 of the second device embodiment of the present application.
  • FIG. 9C2 is a schematic diagram of the circuit structure of the eleventh variation of the second device embodiment of the present application.
  • FIG. 10 is a schematic structural diagram of an application scenario of a transmission device embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of an example of Embodiment 6 of a filtering device of the present application.
  • FIG. 2 shows the structure of the application scenarios of the various embodiments of the present application, which includes: a differential signal sending circuit 31, a differential signal receiving circuit 33, a filter circuit 32 and The differential cable 34, wherein the differential cable 34 has a shielding layer, and the shielding layer is grounded.
  • the differential signal sending circuit 31 sends the differential mode signal, and the common mode signal is filtered by the left filter circuit 32 before entering the cable 34; the differential mode signal is received after being transmitted by the differential cable 34, and the common mode signal is filtered again by the right filter circuit 32 Then it is received by the differential signal receiving circuit 33.
  • the differential cable 34 is replaced with an unshielded cable.
  • the filtering circuit 32 may be a filtering device or a filtering device composed of components.
  • the differential signal sending circuit 31 may be a differential signal sending device or a differential signal sending device
  • the signal receiving circuit 33 may be a differential signal receiving device or a differential signal receiving device.
  • the differential signal sending circuit 31 includes a differential signal output circuit.
  • a differential signal driving circuit is deployed after the filter circuit 32 on the left.
  • the differential signal sending circuit 31 can generate a common-mode signal and send it to the differential signal receiving circuit 33; the differential signal receiving circuit 33 will also additionally generate an interfering common-mode signal, which is back-propagated to the differential signal sending circuit 31 through a differential cable; the differential line
  • the common mode signal can also be coupled to the cable, and sent to the differential signal sending circuit 31 or the differential signal receiving circuit 33; the noise on the ground plane will also become a common mode signal, and sent to the differential signal sending circuit 31 or the differential signal receiving circuit 33.
  • each common-mode signal is classified according to the transmission direction of its coupling into the filter circuit. Taking the filter circuit Fig.
  • the common-mode signal transmitted from the input terminal of the filter circuit 32 to the right is recorded as the first common-mode signal, and record the common-mode signal transmitted to the left from the output end of the filter circuit 32 as a second common-mode signal.
  • Various embodiments of the present application are simultaneously used to improve the filtering performance of the first common-mode signal and the second common-mode signal in the differential line.
  • Embodiment 1 of a filter device is a device composed of two common-mode inductors in series and a differential-mode inductor connected between the differential line and the ground, forming a two-stage cascade filter for the common-mode signal. The effect is better.
  • Fig. 3A shows the structure of Embodiment 1 of a filtering device, which includes common-mode inductors L1_1, differential-mode inductors L2_1 and common-mode inductors L1_2 connected in sequence, and the magnetic fluxes generated by the common-mode signals of the two coils of each common-mode inductor interact with each other Enhanced, the magnetic flux generated by the common mode signal of the two coils of the differential mode inductor cancels each other out.
  • the two coils of the common mode inductor L1_1 are respectively connected in series with the input terminals 1a and 1b of the device; the two coils of the differential mode inductor L2_1 are respectively connected between the two branches of the differential line between L1_1 and L1_2 and the ground terminal 3a and 3b; the two coils of the common mode inductor L1_2 are respectively connected in series between the two coils of the common mode inductor L1_1 and the output terminals 2a and 2b of the device.
  • the absolute value of the common-mode impedance of the common-mode inductor L1_1 and the common-mode inductor L1_2 (in order to express more intuitively and conveniently, in this article, the modulus value of the impedance of the inductor, capacitor or the device containing the inductor and capacitor is also called the absolute value) Both are much larger than the absolute value of the common-mode impedance of the differential-mode inductor L2_1.
  • the absolute value of the differential mode impedance of the differential mode inductor L2_1 is much greater than the absolute values of the differential mode impedance of the common mode inductor L1_1 and the common mode inductor L1_2.
  • the two coils of each common mode inductor in FIG. 3A have the same winding direction. If the two coils are both clockwise or counterclockwise, the direction of the common mode signal current in the two coils is also clockwise. clockwise or counterclockwise. When the two coils of each common mode inductor are wound in different directions, the direction of the common mode signal current is also different. If one of the two coils is wound clockwise and the other is counterclockwise, then the common mode of the two coils One of the signal current directions is clockwise, and the other is counterclockwise.
  • the two coils of the differential mode inductor in Figure 3A have different winding directions, if one of the two coils is clockwise and the other is counterclockwise, then the common mode signal current directions in the two coils are both forward Clockwise or both counterclockwise.
  • the two coils of the differential mode inductor have the same winding direction, one of the common mode signal current directions in the two coils is clockwise, and the other is counterclockwise.
  • the components of the second embodiment of the device are all passive devices.
  • the input and output terminals of the device are interchangeable, and the working principle is the same. The following descriptions assume that the input terminal is on the left side of the figure, and the output terminal is on the right side of the figure.
  • FIG. 3B1 is an analysis diagram of the practical application of the circuit shown in FIG. 3A , and the first common-mode signal is transmitted from left to right.
  • the first common mode signal is sent out from the leftmost differential signal output circuit 1, passes through the cable 10 to the input terminals 1a and 1b of the first embodiment of the filter device, and then successively passes through the first filter module of the first embodiment of the filter device (Fig.
  • the circuit in the dotted line on the left in 3B1) and the common mode inductance L1_2 of the second filter module (the circuit in the dotted line on the right in FIG. circuit (the loads on the two branches of the differential line are Rl1 and Rl2, which form the total load resistance RL).
  • the first filtering module is composed of a common-mode inductor L1_1 and a differential-mode inductor L2_1
  • the second filtering module is composed of a common-mode inductor L1_2 connected in series with load impedances Rl1 and Rl2.
  • L2_1 of the first filtering module is connected in parallel with the second filtering module.
  • the common mode impedance of L1_1, L1_2 and L2_1 be Z1 c , Z3 c and Z2 c
  • the total impedance composed of load impedance Rl1 and Rl2 is RL
  • the output impedance of differential signal output circuit 1 is Rs (in the two branches of the differential line
  • the output impedance on the road is Rs1, Rs2, the total output resistance Rs)
  • the common-mode impedance of the circuit in which L2_1 of the first filter module is connected in parallel with the second filter module is Z4 c
  • the first filter module is connected to the first common-mode signal
  • the attenuation of the first common-mode signal by the second filtering module is G1L2 c
  • the attenuation of the first common-mode signal by the device embodiment is G1L c
  • G1L c G1L1 c *G1L2 c ,
  • G1L2 c can be approximated as:
  • Z4 c can be approximated as: Z4 c ⁇ Z2 c .
  • the attenuation of the first common-mode signal is G1L c , which can be approximately considered as:
  • decibel (d B) is used as the unit of attenuation, there are:
  • the differential mode impedance of L1_1, L1_2 and L2_1 be Z1 d , Z3 d and Z2 d
  • the total impedance of the load composed of load impedance Rl1 and Rl2 to the differential mode signal is also RL
  • the impedance of the differential signal output circuit 1 to the differential mode signal also Rs
  • the differential mode impedance of the circuit in which L2_1 of the first filter module is connected in parallel with the second filter module is Z4 d
  • the attenuation of the differential mode signal by the first filter module is G1L1 d
  • the attenuation of the differential mode signal by the second filter module is G1L2 d
  • the attenuation of the differential mode signal by the whole device is G1L d
  • G1L d G1L1 d *G1L2 d ,
  • Z4 d can be approximated as:
  • G1L1 d can be approximated as:
  • G1L c can be approximated as:
  • decibel (dB) is used as the unit of attenuation, there are:
  • FIG. 3B2 is another effect analysis diagram of the actual application of the circuit shown in FIG. 3A .
  • the second common mode signal is transmitted from right to left.
  • the second common-mode signal is introduced from the rightmost cable 21 (or connector or wiring) or load, and successively passes through the third filter module (the circuit in the dotted line on the right in Figure 3B2) and the fourth filter module ( Figure 3B2
  • the common mode inductance L1_1 in the circuit inside the dotted line box on the left of ) reaches the terminals 1a, 1b, and finally reaches the differential signal output circuit 1 through the cable 11.
  • the third filtering module is composed of a common-mode inductor L1_2 and a differential-mode inductor L2_1, and the fourth filtering module is composed of a common-mode inductor L1_1 connected in series with device impedances Rs1 and Rs2.
  • decibel (d B) is used as the unit of attenuation, there are:
  • the first common mode signal is the noise generated by the differential signal transmission circuit (the differential signal transmission circuit 31 in FIG. 2 ) including the differential signal output circuit 1 in FIG. 3B1 or the external interference or ground plane noise coupled in through the cable 10
  • the second common mode signal is the noise generated by the load of the differential signal in Figure 3B2 or the external interference and ground plane noise coupled in through the cable 21
  • the embodiment of the filtering device is for the differential signal transmission circuit including the differential signal output circuit 1 (for the differential signal transmission circuit in Figure 2 Common mode signals such as the noise generated by the differential signal sending circuit 31), the load of the differential signal (which is the differential signal receiving circuit 33 in FIG. 2 ), noise coupled by cables, or ground plane noise all have a cascaded attenuation effect, The filtering effect is better.
  • This embodiment of the filter device also effectively reduces the external electromagnetic radiation of the cable by suppressing the common-mode signal generated by the differential signal transmission circuit (the differential signal transmission circuit 31 in FIG. 2 ) including the differential signal output circuit 1 .
  • a parallel differential-mode inductor constitutes a cascaded filter device, which performs two-stage attenuation on the common-mode signal generated by the differential signal transmission circuit. The attenuation effect is good, and the influence on the differential-mode signal is small.
  • the signal-to-noise ratio of the differential line signal is better improved; at the same time, the common mode signal generated by the differential line load is also attenuated by two stages, which protects the differential signal transmission circuit.
  • the common-mode input impedance of the input end of the first embodiment of the device is large, which will not cause excessive load of the differential signal sending circuit to generate heat and work abnormally. In addition, it can also effectively filter ground plane noise and common-mode signals coupled through cables, and reduce noise radiation to the outside by reducing common-mode signals on data cables.
  • the winding directions of the two coils in the differential mode inductors used are the same, and the common mode inductors and differential mode inductors are the same choke coils, both of which are the same as those in Figure 3C1.
  • the common mode inductor L1_1 in 3B1 is the same, which simplifies and standardizes the circuit components of the whole device.
  • the common-mode impedance of each common-mode inductor is the same as the differential-mode impedance of the differential-mode inductor, represented by Zc, and the differential-mode impedance of each common-mode inductor is the same as the common-mode impedance of the differential-mode inductor, expressed by Z d said.
  • FIG. 3C2 shows a numerical comparison relationship between the common-mode impedance Z c and the differential-mode impedance Z d of a single broadband common-mode inductor, and the absolute value of Z c is much greater than the absolute value of Z d .
  • the absolute value at the maximum value of Z d is close to RL and Rs, assuming that the absolute value at the maximum value of Z d is equal to RL, and RL is equal to Rs.
  • equations (4), (5) and (6) it can be obtained that within a broadband range, this embodiment has relatively large attenuation of the first common-mode signal and the second common-mode signal, and relatively small attenuation of the differential-mode signal.
  • FIG. 1B and FIG. 1C Comparing the differential filter devices disclosed in FIG. 1A , FIG. 1B and FIG. 1C , the filtering effect in FIG. 1B and FIG. 1C is better than that in FIG. 1A . Taking FIG. 1B and FIG. 1C as examples below, the filtering effects of this specific embodiment and the disclosed technology are compared.
  • the differential mode inductors in Fig. 1C and 1B are the same as this specific embodiment, using two coils wound to the same choke coil, that is, the same as the choke coil of the common mode inductor, and the connection method also adopts this embodiment. way of specific implementation.
  • FIG. 3C3 shows a measured filtering effect diagram of this specific embodiment
  • FIG. 3C4 shows an actual measured filtering effect diagram of FIG. 1B
  • FIG. 3C5 shows an actually measured filtering effect diagram of FIG. 1C . From the comparison of the effects shown in Fig. 3C3 and Fig. 3C4 or Fig. 3C5, the filtering effect of this specific embodiment is 20dB higher than that of the disclosed differential filter device 1B or 1C, and the filtering effect of this specific embodiment is verified from actual tests. good.
  • this specific implementation mode has two-stage attenuation for common-mode signals in both positive and negative directions, and has a good attenuation effect and a high working bandwidth.
  • the common-mode input impedance of the input end of this specific embodiment is large, which will not cause excessive load of the differential-mode signal sending device to generate heat and work abnormally.
  • Embodiment 2 of a filter device After Embodiment 1 of the filter device, several circuit combinations consisting of a common-mode inductor and a differential-mode inductor are sequentially connected to form a multi-stage cascaded filter for common-mode signals.
  • Fig. 4A shows the structure of Embodiment 2 of a filter device, which is formed by sequentially connecting N-1 common-mode inductors and N-1 differential-mode inductors after Embodiment 1 of the filter device.
  • the N-1 common-mode inductors are sequentially connected in series on the differential line, and are respectively numbered L1_3 to L1_N+1, wherein the two coils of each common-mode inductor are respectively connected in series on a branch of the differential line;
  • the N-1 The differential mode inductors are sequentially connected in parallel between the differential line and the ground, and are respectively numbered L2_2 to L2_N, wherein the two coils of each differential mode inductor are respectively connected between a branch of the differential line and the ground.
  • the two coils of each common-mode inductor in FIG. 4A have the same winding direction. If the two coils are both clockwise or counterclockwise, the direction of the common-mode signal current in the two coils is also the same. Clockwise or counterclockwise. When the two coils of each common mode inductor are wound in different directions, the direction of the common mode signal current is also different. If one of the two coils is wound in a clockwise direction and the other is in a counterclockwise direction, then the common mode of the two coils is One of the modulo signal current directions is clockwise, and the other is counterclockwise.
  • the two coils of the differential mode inductor in Figure 4A have different winding directions, if one of the two coils is wound in a clockwise direction and the other is counterclockwise, then the direction of the common-mode signal current in the two coils is Clockwise or both counterclockwise.
  • the two coils of the differential mode inductor have the same winding direction, one of the common mode signal current directions in the two coils is clockwise, and the other is counterclockwise.
  • the components of the second embodiment of the device are all passive devices.
  • the input and output terminals of the device are interchangeable, and the working principle is the same. The following descriptions assume that the input terminal is on the left side of the figure, and the output terminal is on the right side of the figure.
  • FIG. 4B1 is an analysis diagram of the actual application of the circuit shown in 4A (the case where the common mode signal is transmitted from left to right).
  • the first filter module B_i is composed of common mode inductor L1_i and differential mode inductor L2_i
  • the second filter module B is composed of common mode inductor L1_N+1 and load impedance Rl1, Rl2, the differential mode of each first filter module B_i
  • the inductance L2_i is connected in parallel with each filter module of the next stage, and the impedance after the parallel connection is Z4 ic .
  • the total impedance composed of load impedance Rl1 and Rl2 is RL
  • the output impedance of the differential signal output circuit 1 is Rs
  • the attenuation of the common-mode signal by each first filter module B_i is G2L1 ic
  • the second filter module B is G2L1 ic for the common-mode signal
  • the attenuation of the whole device is G2L2 c
  • the attenuation of the common mode signal by the whole device is G2L c
  • G2L2 c can be approximated as:
  • G2L1 ic can be approximated as:
  • the attenuation of the first common-mode signal is G2L c , which can be approximately considered as:
  • decibel (d B) is used as the unit of attenuation, there are:
  • the absolute value of Z1c is much greater than the absolute value of Z2c and RL, the absolute value of G2Lc is larger than the absolute value of G1Lc in the first embodiment of the filter device That is, the attenuation value for the first common-mode signal is increased by at least
  • the differential mode impedance of the circuit in which L2_i of each first filter module B_i is connected in parallel with the lower filter module is Z4 id
  • the attenuation of the differential mode signal by each first filter module B_i is G2L1 id
  • the second filter module B is of the differential mode signal.
  • the attenuation is G2L2 d
  • the attenuation of the differential mode signal by the whole device is G2L d
  • Z4 (N+1)d is equal to RL.
  • decibel (d B) is used as the unit of attenuation, there are:
  • the attenuation of the differential mode signal in the second embodiment of the device is controllable.
  • FIG. 4B2 is another effect analysis diagram of the actual application of the circuit shown in FIG. 4A.
  • the second common mode signal is transmitted from right to left.
  • RS1 and RS2 Rs1 and Rs2 combined as Rs.
  • the third filtering module B_i is composed of a common-mode inductor L1_N-i+2 and a differential-mode inductor L2_N-i+1, and the fourth filtering module is composed of a common-mode inductor L1_1 connected in series with device impedances Rs1 and Rs2.
  • the attenuation of the second common mode signal is G2R c, which can be approximately considered as:
  • decibel (d B) is used as the unit of attenuation, there are:
  • the absolute value of Z1 c is much greater than the absolute value of Z2 c and RS, the absolute value of G2Rc is greater than the absolute value of G1Rc in the first embodiment of the filter device That is, at least the attenuation of the second common-mode signal is increased
  • the differential signal transmission circuit is protected.
  • the second embodiment of the device utilizes at least three common-mode inductors in series and A multi-stage cascaded filtering device composed of two common-mode inductors connected in parallel with a differential-mode inductor, performs multi-stage attenuation on the common-mode signal sent from the differential signal transmission circuit, and the attenuation effect is further improved on the basis of the first embodiment of the filter device , and has little influence on the differential mode signal, and improves the signal-to-noise ratio of the differential line signal in a wide bandwidth; at the same time, it works on the common mode signal introduced from the load of the differential signal and introduced during the transmission process, Multi-stage attenuation is also performed, the attenuation effect is better, and the differential signal transmission circuit is protected.
  • the plane noise and the common-mode signal coupled on the cable can also be filtered in multiple stages to further improve the signal-to-noise ratio of the differential line signal, and the common-mode signal can be cascaded to further reduce the noise on the data cable. Noise radiates outward.
  • each common mode inductor and differential mode inductor are the same choke coils, both of which are the same as those in Fig.
  • the common mode inductor L1_1 in 4A is the same, which simplifies and standardizes the circuit components of the whole device.
  • the common-mode impedance of each common-mode inductor is the same as the differential-mode impedance of the differential-mode inductor, and continues to be represented by Zc
  • the differential-mode impedance of each common-mode inductor is the same as the common-mode impedance of the differential-mode inductor , continue to express with Z d .
  • the attenuation of the device in this embodiment to the differential mode signal is G2L d is:
  • the absolute value of Z c is much greater than the absolute value of Z d .
  • Embodiment 1 of the filtering device in this specific implementation mode the attenuation of the first common-mode signal and the second common-mode signal is increased.
  • the first embodiment of the filter device and the second embodiment of the filter device are two typical filter devices of the present application. In some embodiments, the first embodiment of the filter device or the second embodiment of the filter device are modified.
  • Example 1 is the same as Embodiment 2 of the filtering device, and various variants will be discussed below using Embodiment 2 of the filtering device.
  • FIG. 5A2 is a circuit structure of an example of Variation 2 of Embodiment 2 of the filtering device of the present application, in which two input terminals 1a and 1b of the filtering device are connected in series with capacitors C1a and C1b respectively.
  • FIG. 5A3 is a circuit structure of an example of Variation 3 of Embodiment 2 of the filtering device of the present application, wherein the two output terminals 2a and 2b of the filtering device are connected in series with capacitors C2a and C2b respectively.
  • a diode or a bidirectional diode is respectively connected between the two input ends of the filtering device and the ground, and is used for limiting the signal at the input end of the differential line while preventing static electricity.
  • Fig. 5B1 is the circuit structure of the fourth variation example of the second embodiment of the filter device of the present application, in which a bidirectional diode D1b and a bidirectional diode D1a are respectively connected between the two input terminals 1a and 1b of the device and the ground.
  • FIG. 5B2 is a circuit structure of an example of variation five of Embodiment 2 of the filter device of the present application, in which a bidirectional diode D2b and a bidirectional diode D2a are respectively connected between the two output terminals 2a and 2b of the device and the ground.
  • one of the two coils of a differential mode inductor is respectively connected between the two input terminals of the filter device and the ground, and is used for impedance of the first common mode signal at the input terminal of the differential line. match.
  • Fig. 5C1 is a circuit structure of an example of variation 6 of Embodiment 2 of the filter device of the present application, in which a coil of a differential mode inductor L2_0 is respectively connected between the two input terminals 1a and 1b of the device and the ground.
  • FIG. 5C2 is a circuit structure of an example of Variation 7 of Embodiment 2 of the filtering device of the present application, in which a coil of a differential mode inductor L2_N+1 is respectively connected between the two output terminals 2a and 2b of the filtering device and the ground.
  • the ground terminals of the differential mode inductors in the second embodiment of the filter device are combined and then grounded through capacitors to simplify the circuit.
  • Figure 5D4 is a variant of the second embodiment of the filter device of the present application.
  • the coil ground terminals of each differential mode inductor L2_i are combined into one node, and then connected to the node numbered 3_1 through the capacitor C3_1, and then connected to the ground.
  • FIG. 5E shows Variation 1 to Variation 7 of Embodiment 2 of the filtering device of the present application. Combined circuit structure.
  • the variation 8 or variation 10 of the filtering device embodiment of the present application is combined with at least one variation in the variation 2 to the variation 7, and the variation 9 or variation of the filtering device embodiment of the application is The eleventh variant is combined with at least one variant in the variant two to the seventh variant.
  • Embodiment 3 of a filtering device includes two common-mode inductors in series and two capacitors respectively connected between the two branches of the differential line between them and the ground, forming a secondary cascade connection for the common-mode signal Filtering, and make full use of the frequency characteristics of the combination of multiple inductors and capacitors, the filtering effect is better.
  • Fig. 6A shows the circuit structure of Embodiment 3 of a filter device, which includes common mode inductor L1_1, capacitor C3a, capacitor C3b and common mode inductor L1_2 connected in sequence, when the common mode inductor flows through the two coils of each common mode inductor The magnetic fluxes generated when the signals reinforce each other.
  • the two coils of the common mode inductor L1_1 are respectively connected in series with the input ends 1a and 1b of the filter device; the two coils of the common mode inductor L1_2 are respectively connected in series with the two coils of the common mode inductor L1_1 and the output ends 2a and 2b of the filter device Between; the capacitor C3a and the capacitor C3b are respectively connected between the two branches of the differential line between the two common mode inductors and the ground terminals 3a and 3b.
  • the two coils of each common-mode inductor in FIG. 6A have the same winding direction. If the two coils are both clockwise or counterclockwise, the direction of the common-mode signal current in the two coils is also Is clockwise or counterclockwise. When the two coils of each common mode inductor are wound in different directions, the direction of the common mode signal current is also different. If one of the two coils is wound clockwise and the other is counterclockwise, then the common mode of the two coils One of the signal current directions is clockwise, and the other is counterclockwise.
  • Embodiment 3 of the filtering device are all passive devices.
  • the input end and output end of the filtering device are interchangeable, and the working principle is the same. The following descriptions assume that the input end is on the left side of the figure, and the output end is on the right side of the figure. .
  • the filtering effect of the first common-mode signal propagating from left to right in Embodiment 3 of the filter device will be analyzed first, wherein the common-mode inductor L1_1, capacitor C3a and capacitor C3b form the first-stage filter module C, and the common-mode inductor L1_2 and The load of the device embodiment three constitutes the second-stage filtering module D.
  • the selection of the capacitance value and the inductance value should take into account the frequency characteristics of multiple inductance and capacitance combinations.
  • Figure 6B shows the attenuation of the first common-mode signal by the third embodiment of the filtering device based on the numerical calculation of the above example, and it can be seen from Figure 6B that at 500Mhz, the attenuation of the first common-mode signal by the third embodiment of the filtering device The value is already 65dB, at 1 Ghz it is already over 80dB.
  • Embodiment 3 of the filtering device is symmetrical, the filtering effect on the second common-mode signal propagating from right to left is the same as the filtering effect on the first common-mode signal.
  • the differential mode inductance values of L1_1 and L1_2 are both 0.02 ⁇ H; for example, the capacitance values of C3a and C3b are both 3pF ;
  • the load resistance of the filter device embodiment three is 50 ⁇ , and the output resistance of the upper drive circuit is also 50 ⁇ .
  • FIG. 6C shows the attenuation of the filter device embodiment three pairs of differential mode signals based on the calculation of the above values. From the figure 6C, it can be seen that the third embodiment of the device has very little influence on the differential mode signal.
  • Embodiment 3 of the filtering device are examples, and the actual use is designed according to specific scenarios.
  • Embodiment 3 of a filtering device is composed of two common-mode inductors connected in series and two capacitors respectively connected between the differential line between them and the ground, forming a two-dimensional filter for the common-mode signal. cascaded filtering, and make full use of the frequency characteristics of multiple inductors and capacitors to perform two-stage attenuation on the common-mode signal sent from the differential signal transmission circuit, which improves the differential line in a wide bandwidth.
  • the signal-to-noise ratio of the signal at the same time, it works on the common-mode signal introduced from the load of the differential signal and the transmission process, and also performs two-stage attenuation, which has a good attenuation effect and protects the differential signal transmission circuit.
  • the plane noise and the common-mode signal coupled on the cable can also be filtered twice to further improve the signal-to-noise ratio of the differential line signal, and the common-mode signal can be cascaded to further reduce the noise on the data cable. Noise radiates outward.
  • Embodiment 4 of a filter device after Embodiment 3 of the filter device, several identical circuit combinations are sequentially connected.
  • the circuit combination is composed of a common-mode inductor and two capacitors to form a multi-stage cascaded filter for common-mode signals.
  • FIG. 7 shows the structure of Embodiment 4 of the filter device, which is composed of N-1 common-mode inductors and 2(N-1) capacitors after Device Embodiment 3.
  • the N-1 common-mode inductors are sequentially connected in series on the differential line, and are respectively numbered L1_3 to L1_N+1, wherein the two coils of each common-mode inductor are respectively connected in series on a branch of the differential line; the 2(N- 1)
  • Two capacitors are connected to the differential line, respectively numbered as C3_3 to C3_2N (for unified numbering, capacitors C3a and C3b in Figure 6A correspond to C3_1 to C3_2 in this figure), where the difference between every two common mode inductors Connect a capacitor between each branch of the line and ground.
  • the two coils of each common-mode inductor in FIG. 7 have the same winding direction. If the two coils are both clockwise or counterclockwise, the direction of the common-mode signal current in the two coils is also Is clockwise or counterclockwise. When the two coils of each common mode inductor are wound in different directions, the direction of the common mode signal current is also different. If one of the two coils is wound clockwise and the other is counterclockwise, then the common mode of the two coils One of the signal current directions is clockwise, and the other is counterclockwise.
  • Embodiment 4 of the filtering device are all passive devices.
  • the input end and output end of the filtering device are interchangeable, and the working principle is the same. The following descriptions assume that the input end is on the left side of the figure, and the output end is on the right side of the figure. .
  • the secondary filtering module D implements N+1-level filtering for the first common-mode signal.
  • N-1 first-level filtering modules C are added; and due to the increase in inductance and capacitance, we There are more options to adjust the frequency characteristic of the combination of the inductor and the capacitor, and the filtering effect is further improved on the basis of the third embodiment of the filtering device.
  • Embodiment 4 of the filtering device is symmetrical, the filtering effect on the second common-mode signal propagating from right to left is the same as the filtering effect on the first common-mode signal, that is, the filtering effect is further improved on the basis of Embodiment 3 of the filtering device .
  • the filtering effect of the fourth embodiment of the filter device on the differential mode signal propagating from left to right will be analyzed below, wherein, although N-1 first-stage filter modules C are added, the first-stage filter module C has an effect on the differential-mode signal
  • the attenuation is small, and we can also adjust the parameter values of the inductors and capacitors to optimize the overall frequency characteristics of the combined circuit, so the fourth embodiment of the filter device has very little influence on the differential mode signal.
  • Embodiment 4 of a filter device is a filter device composed of at least three common-mode inductors in series and two capacitors connected between the differential line between every two adjacent common-mode inductors and the ground, Multi-stage attenuation is performed on the common-mode signal sent from the differential signal transmission circuit, the attenuation effect is further improved on the basis of the third embodiment of the filtering device, and the influence on the differential-mode signal is small, and it is better improved in a wider bandwidth The signal-to-noise ratio of the differential line signal is improved; at the same time, multi-stage attenuation is also performed on the common-mode signal introduced from the load of the differential signal and introduced during the transmission process, the attenuation effect is good, and the differential signal transmission circuit is protected.
  • the plane noise and the common-mode signal coupled on the cable can also be filtered in multiple stages to further improve the signal-to-noise ratio of the differential line signal, and the common-mode signal can be cascaded to further reduce the noise on the data cable. Noise radiates outward.
  • the third embodiment of the filtering device and the fourth embodiment of the filtering device are also two typical filtering devices of the present application. In some embodiments, the third embodiment of the filtering device or the fourth embodiment of the filtering device are modified. The third embodiment is the same as the fourth embodiment of the filtering device, and various variants will be discussed below with the fourth embodiment of the filtering device.
  • Variation 1 of Embodiment 4 of the filter device a combined circuit in which a resistor and a capacitor are connected in series is selected to replace each capacitor in Embodiment 4 of the filter device.
  • a capacitor or a combined circuit consisting of a resistor and a capacitor connected in series is connected between the two input terminals of the filter device and the ground, respectively, to achieve input impedance matching.
  • a capacitor or a combined circuit consisting of a resistor and a capacitor in series is connected between the two output terminals of the filter device and the ground, respectively, to achieve output impedance matching.
  • a diode or a bidirectional diode is respectively connected between the two input terminals of the filtering device and the ground to realize amplitude limiting and anti-static.
  • a diode or a bidirectional diode is respectively connected between the two output terminals of the filter device and the ground to realize amplitude limiting and anti-static.
  • FIG. 8 shows a combined circuit structure of Variation 1 to Variation 5 of Embodiment 4 of the filtering device of the present application.
  • Embodiment 5 of a filter device The common modes in Embodiment 1 of a filter device or a variant of Embodiment 1 of a filter device or Embodiment 2 of a filter device or a variant of Embodiment 2 of a filter device
  • the inductor is packaged in one device, and the other circuits remain unchanged.
  • Embodiment 6 of a filtering device and each common mode in Embodiment 3 of a filtering device or a variant of Embodiment 3 of a filtering device or Embodiment 4 of a filtering device or a variant of Embodiment 4 of a filtering device The inductor is packaged in one device, and the other circuits remain unchanged.
  • Fig. 11 shows a possible implementation of Embodiment 6 of a filtering device, in which the common mode inductors of Embodiment 3 of a filtering device are packaged into one device, and other circuits remain unchanged.
  • FIG. 9A1 to FIG. 9C2 Various embodiments of a device device of the present application will be introduced below with reference to FIG. 9A1 to FIG. 9C2 .
  • the present application also provides a device embodiment, which encapsulates the circuits of each filter device embodiment in a device to realize filtering of common mode signals, which includes device embodiment 1, device embodiment 2, device embodiment 3, and device implementation Example 4 and variants and variant combinations of each device embodiment.
  • the first embodiment of the device corresponds to the first embodiment of the filtering device.
  • FIG. 9A1 shows the internal circuit structure of the first embodiment of the device. packaged in one device.
  • the input terminals are 1a and 1b
  • the output terminals are 2a and 2b
  • the ground terminals are 3a and 3b.
  • the second embodiment of the device corresponds to the second embodiment of the filtering device.
  • the input terminals are 1a and 1b
  • the output terminals are 2a and 2b
  • the third embodiment of the device corresponds to the third embodiment of the filtering device.
  • FIG. 9B1 shows the internal circuit structure of the third embodiment of the device, which combines the common-mode inductors L1_1 and L1_2 of the third embodiment of the filtering device shown in FIG. C3b is packaged in one device.
  • the input terminals are 1a and 1b
  • the output terminals are 2a and 2b
  • the ground terminals are 3a and 3b.
  • the fourth embodiment of the device corresponds to the fourth embodiment of the filtering device.
  • the input terminals are 1a and 1b
  • the output terminals are 2a and 2b
  • each device embodiment is different from conventional differential filter devices: within the operating frequency range, between two input terminals and ground, and between two output terminals and ground are in a high-impedance state for common-mode signals.
  • the first variant and combination of the device embodiment respectively correspond to the first variant and combination of the filter device embodiment, and the various common-mode inductors, differential-mode inductors, various unidirectional diodes, Various capacitors and various resistors are packaged in one device, and the external connection method is the same as that of the first variant or combination of the device embodiment.
  • the variants and combinations of the second embodiment of the device correspond to the variants and combinations of the second embodiment of the filtering device respectively, and the various common-mode inductors, differential-mode inductors, various unidirectional diodes, Various capacitors and various resistors are packaged in one device, and the external connection method is the same as that of the second variant or combination of the device embodiment.
  • the three variants and combinations of the device embodiment correspond to the third variant and combination of the filter device embodiment respectively, and the various common-mode inductors, differential-mode inductors, various unidirectional diodes, Various capacitors and various resistors are packaged in one device, and the external connection method is the same as that of the third variant or combination of the device embodiment.
  • the fourth variation and combination of the device embodiment correspond to the fourth variation and combination of the filter device embodiment, and the various common-mode inductors, differential-mode inductors, various unidirectional and bi-directional diodes, Various capacitors and various resistors are packaged in one device, and the external connection method is the same as that of the fourth variant or combination of the device embodiment.
  • the second variant of the device embodiment is taken as an example below to describe the variant or combination of the device embodiment.
  • Variations 1 to 11 of Embodiment 2 of the device correspond to Variations 1 to 11 of Embodiment 2 of the filtering device
  • combinations of variants of Embodiment 2 of the device correspond to combinations of corresponding variants of Embodiment 2 of the filtering device.
  • Figure 9C1 shows the structural diagram of the combination of variants 1 to 7 of the second embodiment of the device, corresponding to the combination of variants 1 to 7 of the second embodiment of the filtering device.
  • various components are added inside the device : Grounding capacitors C2i-1 and C2i of each differential mode inductor L2_i, input capacitors C1a and C1b, output capacitors C2a and C3b, impedance matching differential mode inductors L2_0 and differential mode inductors L2_N+1, input limiting diodes D1a and D1b , output limiting diodes D2a and D2b.
  • the embodiments of the device all use passive components, and when it is a symmetrical circuit, the input end and the output end can be interchanged.
  • the present application also provides an embodiment of a transmission device for propagating a differential mode signal, which includes a differential cable and a first device connected at both ends of the differential cable.
  • the first device is any device embodiment of this application or a variant thereof.
  • embodiment or its variant combination the first device may also be any device embodiment or its variant or its variant combination.
  • the shielding layer of the differential cable may not be grounded, grounded through an inductor, or grounded through a magnetic bead.
  • FIG. 10 shows the structure of an application scenario of an embodiment of a transmission device, which adds two inductors 35 on the basis of FIG. 2 , and grounds through an inductor 35 at both ends of a differential cable 34 .
  • the differential cable 34, two filter circuits 32 and two inductors 35 within the virtual frame in Fig. 10 constitute an embodiment of a transmission device.
  • the shielding layer of the differential cable 34 is grounded mainly to provide a return path for the common-mode signal in the differential cable 34 .
  • the common-mode signal in the differential cable 34 can induce a current in the opposite direction in the shielding layer, so as to reduce external radiation after being superimposed with the common-mode signal.
  • the common-mode signal in the differential cable 34 is attenuated very little, then the main source of radiation on the differential cable 34 is the common-mode noise coupled from the ground wire to the shielding layer of the differential cable 34 .
  • the shielding layer of the differential cable 34 is isolated from the ground with the inductor 35 to reduce the common mode noise coupled from the ground wire to the shielding layer of the differential cable 34 .
  • the shielding layer of the differential cable 34 and the ground can also be isolated by not grounding or using magnetic beads or other filtering devices that filter out corresponding frequency bands.

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Abstract

本申请实施例提供了一种滤波装置，其包括至少两个共模电感和至少一个差模电感，共模电感和差模电感均为具有两个线圈的扼流圈，共模电感的两个线圈在流过共模信号时产生的磁通量互相增强，差模电感的两个线圈在流过共模信号时产生的磁通量互相抵消；各共模电感的一个线圈顺序串联在差分线路的一个支路上，另一个线圈按照所述顺序串联在差分线路的另一个支路上，在相邻的共模电感之间的差分线路的两个支路与地之间分别联接一个差模电感的两个线圈中的一个线圈。本申请实施例还相应地提供了滤波器件和传输装置。本申请实施例的滤波装置、滤波器件和传输装置通过级联滤波的方法降低了共模信号干扰。

Description

一种滤波装置、滤波器件和传输装置 技术领域
本申请涉及电子电路系统，主要涉及差分线路的滤波装置、滤波器件和传输装置。
背景技术
整个电子领域为了应对多功能化和高性能化的要求，数据的处理速度和传输速度都在不断上升，电子设备之间的通讯速率要求也进一步提升。随着串行总线技术的发展，其在高速接口中慢慢形成了现在的主导地位。串行总线技术应用在很多标准中，例如：通用串行总线、高速串行计算机扩展总线标准、以太网、车载以太网、低电压差分信号、高清多媒体接口。
尤其是随着汽车的设计中电子设备大量的增加，各种数据通讯、自动驾驶技术在汽车上的应用，视频设备、车载娱乐设备、辅助驾驶技术的不断发展，不同系统之间的通讯大量使用了串行数据总线。
在高速串行数据的传输中，一般采用差分传输方式。差分传输方式是指以相反相位的差分信号(也称差模信号)传输数据的通讯方式。接收装置根据两个差分信号之间的差值读取串行数据。差分信号有利于信号传输的进一步高速化。
差分信号有利于降低电磁干扰。因为传输差分信号的路径是并行的，而理想的差分信号的交流部分大小相等方向相反，所以他们向外辐射的电磁场大部分是相互抵消的，因而电磁辐射能量较低。而且，当有空间电磁能量传到差分传输路径的时候，由于差分信号线缆的平行排布的特性，噪声经常是以共模噪声(也称共模信号)的方式进入传输路径。在信号的接收电平容限范围内，差分信号接收器可以排除共模噪声干扰。因此差分信号传输数据对外部共模噪声有一定的抑制作用。
在实际的差分信号使用中，差分信号发送电路所发出信号中，由于各种各样的原因总是包含着共模噪声成分；而且对于差分接收电路，当共模噪声超过其共模噪声容限以后，会造成接收数据的丢失，甚至会造成接收电路的损坏。
在利用差分信号传输数据的装置中，为了进一步抑制共模噪声的不良影响，需要在电路中加入对共模噪声的滤波电路。滤波电路包括共模电感，也称共模扼流圈。对于差分信号发送电路，共模电感能减少信号传输中的共模电流。对于接收电路，共模电感将外界输入的共模噪声电平抑制在接收器允许的范围内。
已经公开的滤波器中应用了图1A、图1B，图1C中的电路。
图1A示出了公开的滤波电路一，该滤波电路是一个共模电感，共模电感的作用是加大线路中共模电流阻抗(本文中“阻抗”表示电阻、电容、电感等器件或信号线路限制电流通过的能力。这种限制电流通过的能力不仅仅是由器件或线路件本身电阻引起，也有可能是由于器件或线路自身的电感、电容以及其他等因素引起，或是由这些因素的组合引起。)，从而减小线路上的共模电流。这种电路的缺点是对共模电流的控制依赖于单个共模电感的共模阻抗。
图1B示出了公开的滤波电路二，该滤波电路中一个共模电感并联一个差模电感 (也叫差模扼流圈或常模扼流圈)。其中，共模电感的作用与图1A中一样，差模电感的作用是分流共模电流和对共模信号进行阻抗匹配。这个电路有以下缺点：
(1)当差模电感的共模阻抗大于信号线路的共模阻抗时，差模电感的对线路上共模信号的作用不明显。
(2)一些设计中把差模电感的共模阻抗设计成与信号线路中共模阻抗相等或者相近，用来吸收共模扼流圈反射的共模信号。这种设计导致滤波的频率范围过窄，同时虽然共模电感反射的共模信号被差模电感吸收，但是差分信号驱动电路或差分线缆引入的共模信号依然会沿着信号线路径到达共模电感。而且这部分共模信号衰减并不明显。
(3)当差模电感的共模阻抗远远小于信号线路中的共模阻抗时，可能会导致流过差分信号驱动电路的共模电流过大或共模信号发生负反射，从而导致信号驱动电路工作异常。
图1C示出了公开的滤波电路三，该滤波电路中在一个共模电感的左右两侧各并联一个差模电感，其中，各差模电感对共模扼流圈两侧的共模信号进行分流。这种电路的缺点是：
(1)包含图1B电路所包含的缺点。
(2)由于右边差模电感对共模信号的低阻抗特性，地平面上的噪声很容易以共模噪声的形式被耦合到信号线的线缆上。
发明内容
有鉴于此，本申请实施例提供了一种滤波装置、滤波器件和传输装置。滤波装置通过包含顺序连接的共模电感与差模电感组合的共模信号的滤波电路，在宽带范围内，对差模信号不会产生过大的衰减，对差模信号(为了便于对比，把差分信号表示为差模信号，把共模噪声称为共模信号)传递方向的共模信号实现多级级联的衰减，衰减效果好。同时对从接收端耦合进来的共模信号同样实现多级级联的衰减，保护差分信号发送端的装置。
第一方面，本申请实施例提供了一种滤波装置，用于过滤差分线路中共模信号，该滤波装置包括：至少两个共模电感和至少一个差模电感；共模电感为具有两个线圈的扼流圈，且每个共模电感的两个线圈在流过共模信号时产生的磁通量互相增强，其中，共模电感的一个线圈顺序串联在差分线路的一个支路上，各共模电感的另一个线圈按照顺序串联在差分线路的另一个支路上；差模电感为具有两个线圈的扼流圈，且每个差模电感的两个线圈在流过共模信号时产生的磁通量互相抵消，其中，在相邻的共模电感之间的差分线路的两个支路与地之间分别联接一个差模电感的两个线圈中的一个。
由上，利用至少两个串联的共模电感和每两个共模电感并联一个差模电感组成的多级级联的滤波装置，对从差分信号发送电路发出的共模信号进行多级衰减，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号的负载引入的和传输过程引入的共模信号起作用也进行多级衰减，衰减效果更好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行了多级滤 波，进一步提高差分线路信号的信噪比，还通过级联降低各共模信号进一步减少数据线缆上的噪声向外辐射。
在第一方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输入端与地之间连接的一个差模电感，其中，该差模电感的两个线圈分别联接在所述滤波装置的输入端的差分线路的两个支路与地之间。
由上，通过在滤波装置的输入端与地之间连接的一个差模电感，用于匹配滤波装置与差分信号输出电路之间的阻抗。
在第一方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输出端与地之间连接的一个差模电感，其中，该差模电感的两个线圈分别联接在滤波装置的输出端的差分线路的两个支路与地之间。
由上，通过在滤波装置的输出端与地之间连接的一个差模电感，用于匹配滤波装置与差分信号的负载线路之间的阻抗。
在第一方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输入端的差分线路的两个支路与地之间分别联接的一个二极管，该二极管可为单向或双向二极管。
由上，在该滤波装置的输入端的差分线路的两个支路与地之间分别联接的一个二极管，实现滤波装置的输入限幅和防静电。
在第一方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输出端的差分线路的两个支路与地之间分别联接的一个二极管，该二极管可为单向或双向二极管。
由上，在该滤波装置的输出端的差分线路的两个支路与地之间分别联接的一个二极管，实现滤波装置的输出限幅和防静电。
在第一方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输入端的差分线路的两个支路分别串联的一个第三电路，第三电路至少包括下列之一：电感、电阻、电容、二极管。第三电路的最优方案为电容。
由上，在该滤波装置的输入端的差分线路的两个支路分别串联的一个至少由电感、电阻、电容、二极管中之一组成的电路，对输入信号中直流信号进行匹配或隔离。
在第一方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输出端的差分线路的两个支路分别串联的所述第三电路。
由上，在该滤波装置的输出端的差分线路的两个支路分别串联的一个至少由电感、电阻、电容、二极管中之一组成的电路，对输出信号中直流信号进行匹配或隔离。
在第一方面一种可能的实施方式中，在各差模电感的两个线圈的接地端与地之间还联接的第四电路，第四电路至少包括下列之一：电感、电阻、电容、二极管。第四电路的最优方案为电容。
由上，在各差模电感的两个线圈的接地端与地之间串联的一个至少由电感、电阻、电容、二极管中之一组成的电路，实现滤波装置的与地之间的直流信号进行匹配或隔离，同时是实现上级差分信号输出电路的地与下级差分信号负载电路的地之间的匹配或隔离。
在第一方面一种可能的实施方式中，对若干个各差模电感的两个线圈的接地端进 行合并。
由上，通过若干个各差模电感的两个线圈的接地端进行合并，使滤波装置的电路简单。如果在合并后再通过第四电路接地，则减少第四电路的量，再使滤波装置的电路简单。
第二方面，本申请实施例提供了一种滤波装置，用于过滤差分线路中共模信号，该滤波装置包括：至少两个共模电感和至少一个第一电路，其中，共模电感为具有两个线圈的扼流圈，且每个共模电感的两个线圈在流过共模信号时产生的磁通量互相增强，第一电路包括两个第二电路，该第二电路为电容或电容与电阻的串联电路，其中，共模电感的一个线圈顺序串联在差分线路的一个支路上，各共模电感的另一个线圈按照顺序串联在差分线路的另一个支路上；在相邻的所述共模电感之间的所述差分线路的两个支路与地之间分别联接一个第二电路。
由上，利用至少两个串联的共模电感和每两个共模电感之间差分线路的支路与地之间联接的两个电容或由电容与电阻的串联电路而组成的多级级联的滤波装置，对从差分信号发送电路发出的共模信号进行多级并且具有组合效果的衰减，而且对差模信号影响小，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号的负载引入的和传输过程引入的共模信号起作用也进行多级并且具有组合效果的衰减，衰减效果好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行多级滤波，进一步提高差分线路信号的信噪比，还通过级联降低各共模信号进一步减少数据线缆上的噪声向外辐射。
在第二方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输入端的差分线路的两个支路与地之间分别联接的一个所述第二电路。
由上，通过在滤波装置的输入端的差分线路的两个支路与地之间分别联接的一个电容或电容与电阻的串联电路，实现滤波装置与差分信号输出电路及对应差分传输线路的阻抗匹配。
在第二方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输出端的所述差分线路的两个支路与地之间分别联接的一个所述第二电路。
由上，通过在滤波装置的输出端的差分线路的两个支路与地之间分别联接的一个电容或电容与电阻的串联电路，实现滤波装置与差分信号传输线缆或板卡差分走线或负载电路之间的阻抗匹配。
在第二方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输入端的差分线路的两个支路与地之间分别联接的一个二极管，该二极管为单向或双向二极管。
由上，在该滤波装置的输入端的差分线路的两个支路与地之间分别联接的一个二极管，实现滤波装置的输入限幅和防静电。
在第二方面一种可能的实施方式中，所述滤波装置还包括：在该滤波装置的输出端的所述差分线路的两个支路与地之间分别联接的一个二极管，该二极管为单向或双向二极管。
由上，在该滤波装置的输出端的差分线路的两个支路与地之间分别联接的一个二 极管，实现滤波装置的输出限幅和防静电。
第三方面，本申请实施例还提供一种滤波器件，包括本申请实施例的第一方面的所述滤波装置或本申请实施例第二方面的所述滤波装置。
由上，把本申请实施例第一方面的所述滤波装置或本申请实施例第二方面的所述滤波装置封装在一个器件里，生成对共模信号的多级级联的滤波装置，对从差分信号发送电路发出的共模信号进行多级衰减，而且对差模信号影响小，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号的负载引入的和传输过程引入的共模信号起作用也进行多级衰减，衰减效果好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行多级滤波，进一步提高差分线路信号的信噪比，还通过级联降低各共模信号进一步减少数据线缆上的噪声向外辐射。
在第三方面一种可能的实施方式中，当所述滤波器件包括本申请实施例的第一方面的所述滤波装置时，所述滤波器件包括本申请实施例的第一方面的所述滤波装置的任何可能的实施方式。
由上，把本申请实施例第一方面的所述滤波装置的任何可能的实施方式封装在一个器件，实现本申请实施例的第一方面的所述滤波装置的各可能的实施方式对应的功能。
在第三方面一种可能的实施方式中，当所述滤波器件包括本申请实施例的第二方面的所述滤波装置时，所述滤波器还包括本申请实施例的第二方面的所述滤波装置的任何可能的实施方式。
由上，把本申请实施例的第二方面的所述滤波装置的任何可能的实施方式封装在一个器件，实现本申请实施例的第二方面的所述滤波装置的各可能的实施方式对应的功能。
第四方面，本申请实施例还提供一种滤波装置，包括：封装本申请实施例的第一方面或第一方面任一可能的实施方式中的各共模电感的器件、和本申请实施例的第一方面或第一方面任一可能的实施方式中其他电路。
由上，本申请实施例的第四方面具有本申请实施例的第一方面或第一方面任一可能的实施方式的优点。
第五方面，本申请实施例还提供一种滤波装置，包括：封装本申请实施例的第二方面或第二方面任一可能的实施方式中的各共模电感的器件、和本申请实施例的第二方面或第二方面任一可能的实施方式中其他电路。
由上，本申请实施例的第五方面具有本申请实施例的第二方面或第二方面任一可能的实施方式的优点。
第六方面，本申请实施例还提供一种传输装置，包括：差分线缆；差分线缆两端连接下列装置或器件之一：
基于本申请实施例的第一方面或第一方面的任一可能实施方式中所述滤波装置；
基于本申请实施例的第二方面或第二方面的任一可能实施方式中所述滤波装置；
本申请实施例的第三方面或第三方面的任一可能实施方式中所述器件；
本申请实施例的第四方面所述滤波装置；
本申请实施例的第五方面所述滤波装置。
由上，传输装置包括对共模信号多级级联滤波的滤波装置或滤波器件，实现对从差分信号发送电路发出的共模信号进行多级衰减，而且对差模信号影响小，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号接收电路引入的和传输过程引入的共模信号起作用也进行多级衰减，衰减效果更好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行了多级滤波，提高差分线路信号的信噪比，还通过级联降低各数据线缆上的共模信号，减少噪声向外辐射。
在第六方面一种可能的实施方式中，在差分线缆两端的屏蔽线与地之间包括下面任一连接方式：不连接；通过电感连接；通过磁珠连接。
由上，差分线缆的屏蔽线与地之间：不连接；通过电感连接；通过磁珠连接，这些方式实现差分线缆的屏蔽线与地之间的隔离，当多级级联滤波的滤波装置或滤波器件降低差分线路中的共模信号时，通过上述隔离，降低地线耦合到差分线缆的屏蔽层的共模噪声。
附图说明
图1A为公开的滤波电路一的示意图；
图1B为公开的滤波电路二的示意图；
图1C为公开的滤波电路三的示意图；
图2为本申请各实施例的传统应用场景的结构示意图；
图3A为本申请的一种滤波装置实施例一的结构示意图；
图3B1为本申请的一种滤波装置实施例一的一种实际应用的效果分析示意图；
图3B2为本申请的一种滤波装置实施例一的另一种的实际应用的效果分析示意图；
图3C1为本申请的一种滤波装置实施例一的具体实施方式的结构示意图；
图3C2为一种共模电感的共模阻抗绝对值与差模阻抗绝对值随频率变化的示意图；
图3C3为本申请的一种滤波装置实施例一的具体实施方式的滤波效果示意图；
图3C4为公开的滤波电路二的滤波效果示意图；
图3C5为公开的滤波电路三的滤波效果示意图；
图4A为本申请的一种滤波装置实施例二的结构示意图；
图4B1为本申请的一种滤波装置实施例二的一种的实际应用的效果分析示意图；
图4B2为本申请的一种滤波装置实施例二的另一种的实际应用的效果分析示意图；
图4C为本申请的一种滤波装置实施例二的具体实施方式的结构示意图；
图5A1为本申请的一种滤波装置实施例二的变体一的结构示意图；
图5A2为本申请的一种滤波装置实施例二的变体二的结构示意图；
图5A3为本申请的一种滤波装置实施例二的变体三的结构示意图；
图5B1为本申请的一种滤波装置实施例二的变体四的结构示意图；
图5B2为本申请的一种滤波装置实施例二的变体五的结构示意图；
图5C1为本申请的一种滤波装置实施例二的变体六的结构示意图；
图5C2为本申请的一种滤波装置实施例二的变体七的结构示意图；
图5D1为本申请的一种滤波装置实施例二的变体八的结构示意图；
图5D2为本申请的一种滤波装置实施例二的变体九的结构示意图；
图5D3为本申请的一种滤波装置实施例二的变体十的结构示意图；
图5D4为本申请的一种滤波装置实施例二的变体十一的结构示意图；
图5E为本申请的一种滤波装置实施例二的变体一至变体七组合的电路结构示意图；
图6A为本申请的一种滤波装置实施例三的的电路结构示意图；
图6B为本申请的一种滤波装置实施例三对第一共模信号的衰减值示意图；
图6C为本申请的一种滤波装置实施例三对差模信号的衰减值示意图；
图7为本申请的一种滤波装置实施例四的的电路结构示意图；
图8为本申请的一种滤波装置实施例四变体一至变体五的组合的电路结构示意图；
图9A1为本申请的一种器件实施例一的内部电路结构示意图；
图9A2为本申请的一种器件实施例二的内部电路结构示意图；
图9B1为本申请的一种器件实施例三的内部电路结构示意图；
图9B2为本申请的一种器件实施例四的内部电路结构示意图；
图9C1为本申请的一种器件实施例二变体一至七组合的电路结构图；
图9C2为本申请的一种器件实施例二变体十一的电路结构示意图；
图10为本申请的一种传输装置实施例的应用场景的结构示意图；
图11为本申请的一种滤波装置实施例六的一个示例的结构示意图。
具体实施方式
在以下的描述中，涉及到“一些实施例”，其描述了所有可能实施例的子集，但是可以理解，“一些实施例”可以是所有可能实施例的相同子集或不同子集，并且可以在不冲突的情况下相互结合。
在以下的描述中，所涉及的术语“第一\第二\第三等”或模块A、模块B、模块C等，仅用于区别类似的对象，或用于区别不同的实施例，不代表针对对象的特定排序，可以理解地，在允许的情况下可以互换特定的顺序或先后次序，以使这里描述的本申请实施例能够以除了在这里图示或描述的以外的顺序实施。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。本文中所使用的术语只是为了描述本申请实施例的目的，不是旨在限制本申请。
下面结合图2至图11介绍本申请的各实施例。
首先结合图2介绍本申请各实施例的传统应用场景，图2示出了本申请各实施例的应用场景的结构，其包括：差分信号发送电路31、差分信号接收电路33、滤波电路32和差分线缆34，其中，差分线缆34带有屏蔽层，屏蔽层接地。
差分信号发送电路31发送差模信号，经过左边的滤波电路32过滤共模信号后进入线缆34；差模信号经过差分线缆34传输后被接收，经过右边的滤波电路32再次过滤共模信号后被差分信号接收电路33接收。
在一些实施例中，把差分线缆34替换成不带屏蔽层的线缆。
在一些实施例中，滤波电路32可以为元器件组成的滤波装置或滤波器件。
在一些实施例中，差分信号发送电路31可以为差分信号发送器件或差分信号发送设备，信号接收电路33可以为差分信号接收设备或差分信号接收器件。
在一些实施例中，差分信号发送电路31中包括差分信号输出电路。
在一些实施例中，在左边的滤波电路32后还部署差分信号驱动电路。
差分信号发送电路31可以产生共模信号，向差分信号接收电路33发送；差分信号接收电路33也会额外产生干扰的共模信号，通过差分线缆反向传播至差分信号发送电路31；差分线缆上也可以耦合进来共模信号，向差分信号发送电路31或差分信号接收电路33发送；地平面的噪声也会成为共模信号，向差分信号发送电路31或差分信号接收电路33发送。为了便于描述，对各共模信号按照其耦合进入滤波电路的传输方向进行分类，以滤波电路图2为例，把从滤波电路32输入端进来的向右传输的共模信号记录成为第一共模信号，把从滤波电路32输出端进来的向左传输的共模信号记录成为第二共模信号。本申请各实施例同时用于提高对差分线路中的第一共模信号和第二共模信号的滤波性能。
下面结合附图介绍本申请的一种滤波装置各实施例。
【一种滤波装置实施例一】
一种滤波装置实施例一采用两个串联的共模电感和二者之间的差分线路与地之间连接的一个差模电感组成的装置，对共模信号形成了二级级联滤波，滤波效果较好。
图3A示出了一种滤波装置实施例一的结构，其包括顺序连接的共模电感L1_1、差模电感L2_1和共模电感L1_2，每个共模电感两个线圈中共模信号产生的磁通量相互增强，差模电感两个线圈中共模信号产生的磁通量互相抵消。其中，共模电感L1_1的两个线圈分别串联在装置的输入端1a和1b；差模电感L2_1的两个线圈分别联接在L1_1与L1_2之间的差分线路的两个支路与接地端3a和3b之间；共模电感L1_2的两个线圈分别串联在共模电感L1_1的两个线圈与装置的输出端2a和2b之间。
共模电感L1_1和共模电感L1_2的共模阻抗绝对值(为了表述更直观和更方便，在本文中对电感、电容或包含电感、电容的器件的阻抗的模值，我们也叫做绝对值)均远大于差模电感L2_1的共模阻抗绝对值。差模电感L2_1的差模阻抗绝对值远大于共模电感L1_1和共模电感L1_2的差模阻抗绝对值。
示例地，图3A各共模电感的两个线圈绕向相同，设该两个线圈绕向均为顺时针方向或逆时针方向，则其两个线圈中的共模信号电流方向也均为顺时针方向或逆时针方向。当各共模电感的两个线圈绕向不同，其共模信号电流方向也不同，设该两个线圈绕向一个为顺时针方向，另一个为逆时针，则其两个线圈中的共模信号电流方向一个是顺时针方向，另外一个为逆时针方向。
示例地，图3A差模电感的两个线圈绕向不同，设该两个线圈绕向一个为顺时针方向，另一个为逆时针，则其两个线圈中的共模信号电流方向均为顺时针方向或均为逆时针方向。当差模电感的两个线圈绕向相同时，则其两个线圈中的共模信号电流方向一个是顺时针方向，另外一个为逆时针方向。
装置实施例二的各元器件都是无源器件，装置的输入端与输出端可以互换，而且工作原理相同，下面的描述均假设输入端在图的左边，输出端在图的右边。
图3B1是图3A所示的电路实际应用的效果分析图，第一共模信号从左到右传递。第一共模信号从最左侧的差分信号输出电路1发送出来，经过线缆10到达滤波装置实施例一的输入端1a和1b，然后先后经过滤波装置实施例一的第一滤波模块(图3B1中左边的虚线框内电路)和第二滤波模块(图3B1中右边的虚线框内电路)的共模电感L1_2到达滤波装置实施例一的输出端2a和2b，最后经过线缆20到达负载电路(其在差分线路的两个支路上的负载为Rl1、Rl2，组成总负载阻值RL)。
第一滤波模块由共模电感L1_1和差模电感L2_1组成，第二滤波模块由共模电感L1_2和负载阻抗Rl1、Rl2串联组成。其中，第一滤波模块的L2_1与第二滤波模块并联。
设L1_1、L1_2和L2_1的共模阻抗为Z1 c、Z3 c和Z2 c，负载阻抗Rl1、Rl2组成的总阻抗为RL，差分信号输出电路1的输出阻抗为Rs(在差分线路的两个支路上的输出阻抗为Rs1、Rs2，组成的总输出阻值Rs)，第一滤波模块的L2_1与第二滤波模块并联的电路的共模阻抗为Z4 c，第一滤波模块对第一共模信号的衰减为G1L1 c，第二滤波模块对第一共模信号的衰减为G1L2 c，装置实施例一对第一共模信号的衰减为G1L c，则有：
G1L c＝G1L1 c*G1L2 c，
其中，
Figure PCTCN2022111503-appb-000001
Figure PCTCN2022111503-appb-000002
Figure PCTCN2022111503-appb-000003
因为Z3 c的绝对值远大于RL，则G1L2 c可以近似为：
Figure PCTCN2022111503-appb-000004
又因为Z2 c的绝对值远大于RL，Z3 c的绝对值远大于Z2 c的绝对值，则Z4 c可以近似为：Z4 c≈Z2 c。
又因为Z1 c的绝对值远大于Rs和Z2 c，Z4 c的绝对值约等于Z2 c的绝对值，则GL1 c可以近似为：
Figure PCTCN2022111503-appb-000005
装置实施例一对第一共模信号的衰减为G1L c可以近似认为：
Figure PCTCN2022111503-appb-000006
当共模电感L1_1和共模电感L1_2为相同的共模电感时，Z1 c与Z3 c相同，则G1L c可以近似认为：
Figure PCTCN2022111503-appb-000007
如果用分贝(d B)作为衰减的单位，则有：
Figure PCTCN2022111503-appb-000008
因为Z1 c的绝对值远大于Z2 c的绝对值和RL，由上式可知，所以G1Lc非常小，即对第一共模信号衰减较大。需要注意的是在本申请各实施例中对数表示的衰减值为负值，其绝对值越大，则衰减越大。
设L1_1、L1_2和L2_1的差模阻抗为Z1 d、Z3 d和Z2 d，负载阻抗Rl1、Rl2组成负载对差模信号的总阻抗也为RL，差分信号输出电路1的对差模信号的阻抗也为Rs，第一滤波模块的L2_1与第二滤波模块并联的电路的差模阻抗为Z4 d，第一滤波模块对差模信号的衰减为G1L1 d，第二滤波模块对差模信号的衰减为G1L2 d,整个装置对差模信号的衰减为G1L d，则有：
G1L d＝G1L1 d*G1L2 d，
其中，
Figure PCTCN2022111503-appb-000009
Figure PCTCN2022111503-appb-000010
Figure PCTCN2022111503-appb-000011
因为Z2 d的绝对值远大于Z3 d的绝对值，则Z4 d可近似为：
Z4 d≈Z3 d+RL，
则G1L1 d可近似为：
Figure PCTCN2022111503-appb-000012
则G1L d可近似为
Figure PCTCN2022111503-appb-000013
当共模电感L1_1和共模电感L1_2为相同的共模电感时，Z1 d与Z3 d相同，则G1L c可以近似认为：
Figure PCTCN2022111503-appb-000014
如果用分贝(dB)作为衰减的单位，则有：
Figure PCTCN2022111503-appb-000015
又因为Z1 d的绝对值和Z3 d的绝对值的最大值与RL和Rs相当，G1L d接近于0，衰减 较小。
图3B2是图3A所示的电路实际应用的另一种效果分析图。其中，第二共模信号从右到左传递。第二共模信号从最右侧的线缆21(或接插件或走线)或负载引入，先后经过第三滤波模块(图3B2中右边的虚线框内电路)和第四滤波模块(图3B2中左边的虚线框内电路)中的共模电感L1_1，到达端子1a，1b，最后通过线缆11到达差分信号输出电路1。
第三滤波模块由共模电感L1_2和差模电感L2_1组成，第四滤波模块由共模电感L1_1和器件阻抗Rs1、Rs2串联组成。
把图3B2中第三滤波模块和第四滤波模块分别看作图3B1中的第一滤波模块和第二滤波模块，且负载阻抗为Rs，利用上述图3B1方法可以得到方法装置实施例一对第二共模信号的衰减为G1R c可以近似认为：
Figure PCTCN2022111503-appb-000016
如果用分贝(d B)作为衰减的单位，则有：
Figure PCTCN2022111503-appb-000017
因为Z1 c的绝对值远大于Z2 c的绝对值和Rs，所以G1Rc非常小，对第二共模信号衰减较大，保护了差分信号发送电路。
因为第一共模信号是图3B1中包含差分信号输出电路1的差分信号发送电路(为图2中差分信号发送电路31)产生的噪声或通过线缆10耦合进来外界干扰或地平面噪声，第二共模信号是图3B2差分信号的负载产生的噪声或通过线缆21耦合进来外界干扰及地平面噪声，本滤波装置实施例对包含差分信号输出电路1的差分信号发送电路(为图2中差分信号发送电路31)产生的噪声、差分信号的负载(为图2中差分信号接收电路33)产生的噪声、线缆耦合的噪声或地平面噪声等共模信号均具有级联的衰减作用，滤波效果较好。
本滤波装置实施例还通过抑制包含差分信号输出电路1的差分信号发送电路(为图2中差分信号发送电路31)产生的共模信号有效地减少线缆的对外电磁辐射。
综上，利用共模电感的共模阻抗高差模阻抗低的特点和差模电感的共模阻抗低差模阻抗高的特点，滤波装置实施例一的两个串联的共模电感和二者之间一个并联的差模电感组成了级联滤波装置，对差分信号发送电路产生的共模信号进行二级衰减，衰减效果好，而且对差模信号影响小，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对差分线路负载产生的共模信号也进行二级衰减，保护了差分信号发送电路。装置实施例一的输入端的共模输入阻抗大，不会造成差分信号发送电路负载过大而发热和工作异常。另外，还可以有效滤除地平面噪声和通过线缆上耦合的共模信号，还通过降低数据线缆上的共模信号减少噪声向外辐射。
【一种滤波装置实施例一的具体实施方式】
在本具体实施方式中，以图3C1中的装置为例，使用的差模电感中的两个线圈的绕向相同，且各共模电感与差模电感为相同的扼流圈，均与图3B1中的共模电感 L1_1相同，使整个装置的电路元器件简单化和标准化。
因此，在本具体实施方式中，各共模电感的共模阻抗与差模电感的差模阻抗相同，用Zc表示，各共模电感的差模阻抗与差模电感的共模阻抗相同，用Z d表示。
又同样设图3C1中的装置右边所接负载的负载阻抗为RL，左边输入差分信号的装置的阻抗为Rs。利用【一种滤波装置实施例一】中的方法，计算本具体实施方式中的装置对第一共模信号的衰减G1L c、对差模信号的衰减为G1L d和对第二共模信号的衰减G1R c，且各衰减均用dB为单位，可以得到类似式(1)、(2)和(3)，但把其中的各共模电感的共模阻抗与差模电感的差模阻抗用Z c表示，把其中各共模电感的差模阻抗与差模电感的共模阻抗用Z d表示，则可以得到本具体实施方式中的装置对第一共模信号的衰减G1L c为：
Figure PCTCN2022111503-appb-000018
本具体实施方式中的装置对差模信号的衰减为G1L d为：
Figure PCTCN2022111503-appb-000019
本具体实施方式中的装置对第二共模信号的衰减G1R c：
Figure PCTCN2022111503-appb-000020
示例地，图3C2示出了某单个宽带的共模电感的共模阻抗Z c和差模阻抗Z d的数值对比关系，Z c的绝对值远大于Z d的绝对值。Z d的最大值处绝对值与RL、Rs相近，假设Z d的最大值处绝对值等于RL，且RL等于Rs。代入式(4)、(5)和(6)可以得到，在宽带范围内本具体实施方式对第一共模信号和第二共模信号的衰减较大，对差模信号的衰减较小。
对比图1A、图1B和图1C中公开的差分滤波装置，图1B和图1C比图1A的滤波效果好。下面以图1B和图1C为例，对比本具体实施方式与公开技术的滤波效果。
为了便于对比，图1C图和1B中的各差模电感如本具体实施方式一样，使用两个线圈绕向相同的扼流圈，即与共模电感的扼流圈相同，其连接方式也采用本具体实施方式的方式。
图3C3示出了实测的本具体实施方式的滤波效果图，图3C4示出了实测的图1B的滤波效果图，图3C5示出了实测的图1C的滤波效果图。从图3C3与图3C4或图3C5示出的效果的对比，本具体实施方式的滤波效果比公开的差分滤波装置1B或1C要高20dB,从实际测试上验证了本具体实施方式的滤波效果较好。
综上，本具体实施方式具有对正反两个方向的共模信号均具有二级衰减，衰减效果好，而且工作带宽高。本具体实施方式的输入端的共模输入阻抗大，不会造成差模信号发送器件负载过大而发热和工作异常。
【一种滤波装置实施例二】
一种滤波装置实施例二在一种滤波装置实施例一之后再顺序连接若干个由一个共模电感和一个差模电感组成的电路组合，对共模信号形成多级的级联滤波。
图4A示出了一种滤波装置实施例二的结构，其在滤波装置实施例一之后再顺序 连接N-1个共模电感和N-1个差模电感组成。该N-1个共模电感顺序串联在差分线路上，分别编号为L1_3至L1_N+1，其中，每个共模电感的两个线圈分别串联在差分线路的一个支路上；该N-1个差模电感顺序并联在差分线路与地之间，分别编号为L2_2至L2_N，其中，每个差模电感的两个线圈分别联接在差分线路的一个支路与地之间。
示例地，图4A各共模电感的两个线圈绕向相同，设该两个线圈绕向均为顺时针方向或逆时针方向，则其两个线圈中的共模信号电流方向也均为是顺时针方向或逆时针方向。当各共模电感的两个线圈绕向不同，其共模信号电流方向也不同，设该两个线圈绕向一个为顺时针方向，另一个为逆时针方向，则其两个线圈中的共模信号电流方向一个是顺时针方向，另外一个为逆时针方向。
示例地，图4A差模电感的两个线圈绕向不同，设该两个线圈绕向一个为顺时针方向，另一个为逆时针方向，则其两个线圈中的共模信号电流方向均为顺时针方向或均为逆时针方向。当差模电感的两个线圈绕向相同时，则其两个线圈中的共模信号电流方向一个是顺时针方向，另外一个为逆时针方向。
装置实施例二的各元器件都是无源器件，装置的输入端与输出端可以互换，而且工作原理相同，下面的描述均假设输入端在图的左边，输出端在图的右边。
在实际应用中，各共模电感L1_i(i＝1,2,…,N+1)可以相同，也可以不同，各差模电感L2_i(i＝1,2,…,N)可以相同，也可以不同，但分析方法都是相同的，无论各共模电感L1_i相同或不同，以及无论各差模电感L2_i相同或不同，都是本申请的保护范围，
为了便于描述，设共模电感L1_i相同，其共模阻抗均为Z1 c，差模阻抗均为Z1 d；设差模电感L2_i相同，共模阻抗相同且为Z2 c，差模阻抗均为Z2 d。在宽带范围内，Z1 c的绝对值远大于Z2 c，Z2 d的绝对值远大于Z1 d的绝对值。
图4B1是4A所示的电路实际应用的效果分析图(共模信号从左到右传递的情况)。共模信号从最左侧差分信号输出电路1发送出来，经过线缆10到达端子1a和1b，经过装置实施例二滤波后从端子2a和2b向外发送，经过线缆20到达差分信号的负载，其中，先后经过各第一滤波模块B_i(i＝1,2,…,N)(图4B1中左边的N个虚线框内电路)、第二滤波模块B(图4B1中右边的虚线框内电路)。其中，第一滤波模块B_i都是由共模电感L1_i和差模电感L2_i组成，第二滤波模块B由共模电感L1_N+1和负载阻抗Rl1、Rl2组成，各第一滤波模块B_i的差模电感L2_i与各下一级的滤波模块并联，且并联后的阻抗为Z4 ic。
同样设负载阻抗Rl1、Rl2组成的总阻抗为RL，差分信号输出电路1的输出阻抗为Rs，各第一滤波模块B_i对共模信号的衰减为G2L1 ic，第二滤波模块B对共模信号的衰减为G2L2 c，整个装置对共模信号的衰减为G2L c，则有：
Figure PCTCN2022111503-appb-000021
其中，
Figure PCTCN2022111503-appb-000022
Figure PCTCN2022111503-appb-000023
Figure PCTCN2022111503-appb-000024
Figure PCTCN2022111503-appb-000025
其中，Z4 (N+1)c等于RL。
因为Z1 c的绝对值远大于RL，则G2L2 c可以近似为：
Figure PCTCN2022111503-appb-000026
又因为Z1 c的绝对值远大于RL，Z1 c的绝对值远大于Z2 c的绝对值，则可以近似为：
Z4 ic≈Z2 c,i＝1,2,…,N。
又因为Z1 c的绝对值远大于Z2 c和RS，Z4 ic的绝对值约等于Z2 c的绝对值，则G2L1 ic可以近似为：
Figure PCTCN2022111503-appb-000027
装置实施例二对第一共模信号的衰减为G2L c可以近似认为：
Figure PCTCN2022111503-appb-000028
如果用分贝(d B)作为衰减的单位，则有：
Figure PCTCN2022111503-appb-000029
因为Z1 c的绝对值远大于Z2 c的绝对值和RL，所以G2Lc的绝对值比滤波装置实施例一的G1Lc的绝对值大
Figure PCTCN2022111503-appb-000030
即对第一共模信号衰减值至少被增大
Figure PCTCN2022111503-appb-000031
设各第一滤波模块B_i的L2_i与下级滤波模块并联的电路的差模阻抗为Z4 id，各第一滤波模块B_i对差模信号的衰减为G2L1 id，第二滤波模块B对差模信号的衰减为G2L2 d,整个装置对差模信号的衰减为G2L d，则有：
Figure PCTCN2022111503-appb-000032
其中，
Figure PCTCN2022111503-appb-000033
Figure PCTCN2022111503-appb-000034
Figure PCTCN2022111503-appb-000035
Figure PCTCN2022111503-appb-000036
其中，Z4 (N+1)d等于RL。
因为Z2 d的绝对值远大于Z1 d和RL的绝对值，则可近似为：
Z4 id≈(N-i+1)*Z1 d+RL，i＝1,2,…,N。
则：可近似为
Figure PCTCN2022111503-appb-000037
如果用分贝(d B)作为衰减的单位，则有：
Figure PCTCN2022111503-appb-000038
因为RL、RS和Z1 d的绝对值相当，装置实施例二对差模信号的衰减可控。
图4B2是图4A所示的电路实际应用的另一种效果分析图。其中，第二共模信号从右到左传递。第二共模信号从最右侧的线缆(或接插件或走线)21或负载引入，先后经过各第三滤波模块B_i,i＝1,2,…,N(图4B2中右边的N个虚线框内电路)和第四滤波模块B(图4B2中左边的虚线框内电路)中的L1_1，到达端子1a，1b，最后通过线缆11到达差分信号输出电路1，其中差分信号输出电路1以器件阻抗RS1和RS2表达(Rs1和Rs2组合为Rs)。
第三滤波模块B_i由共模电感L1_N-i+2和差模电感L2_N-i+1组成，第四滤波模块由共模电感L1_1和器件阻抗Rs1、Rs2串联组成。
把图4B2中的第三滤波模块B_i看作为图4B1中的第一滤波模块B_i，把图4B2中的第四滤波模块看作为图4B1中的第二滤波模块B，利用上述图4B1方法可以得到方法装置实施例二对第二共模信号的衰减为G2R c可以近似认为：
Figure PCTCN2022111503-appb-000039
如果用分贝(d B)作为衰减的单位，则有：
Figure PCTCN2022111503-appb-000040
因为Z1 c的绝对值远大于Z2 c的绝对值和RS，所以G2Rc绝对值比滤波装置实施例一的G1Rc的绝对值增大
Figure PCTCN2022111503-appb-000041
即对第二共模信号至少衰减被增大
Figure PCTCN2022111503-appb-000042
保护了差分信号发送电路。
综上，利用共模电感的共模阻抗高、差模阻抗低的特点和差模电感的共模阻抗低、差模阻抗高的特点，装置实施例二利用至少三个串联的共模电感和每两个共模电感并联一个差模电感组成的多级级联的滤波装置，对从差分信号发送电路发出的共模信号进行多级衰减，衰减效果在滤波装置实施例一的基础上进一步提高，而且对差模信号影响小，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号的负载引入的和传输过程引入的共模信号起作用，也进行多级衰减，衰减效果更好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行了多级滤波，进一步提高差分线路信号的信噪比，还通过级联降低各共模信号进一步减少数据线缆上的噪声向外辐射。
【一种滤波装置实施例二的具体实施方式】
在本具体实施方式中，以图4C中的装置为例，使用的差模电感中的两个线圈的绕向相同，且各共模电感与差模电感为相同的扼流圈，均与图4A中的共模电感L1_1相同，使整个装置的电路元器件简单化和标准化。
因此，在本具体实施方式中，各共模电感的共模阻抗与差模电感的差模阻抗相同， 继续用Z c表示，各共模电感的差模阻抗与差模电感的共模阻抗相同，继续用Z d表示。
又同样设图4C中的装置右边所接负载的负载阻抗为RL，左边输入差分信号的装置的阻抗为Rs。利用【一种滤波装置实施例二】中的方法，计算本具体实施方式中的装置对第一共模信号的衰减G2L c、对差模信号的衰减为G2L d和对第二共模信号的衰减G2R c，且各衰减均用dB为单位，可以得到类似式(7)、(8)和(9)，但把其中的各共模电感的共模阻抗与差模电感的差模阻抗用Z c表示，把其中各共模电感的差模阻抗与差模电感的共模阻抗用Z d表示，则可以得到本具体实施方式中的装置对第一共模信号的衰减G2L c为：
Figure PCTCN2022111503-appb-000043
本具体实施方式中的装置对差模信号的衰减为G2L d为：
Figure PCTCN2022111503-appb-000044
本具体实施方式中的装置对第二共模信号的衰减G2R c：
Figure PCTCN2022111503-appb-000045
继续使用图3C2示例出的宽带的共模电感的共模阻抗Z c和宽带的共模电感的差模阻抗Z d的数值对比关系，Z c的绝对值远大于Z d的绝对值。本具体实施方式与滤波装置实施例一对比，对第一共模信号和第二共模型号的衰减均增加
Figure PCTCN2022111503-appb-000046
Figure PCTCN2022111503-appb-000047
【一种滤波装置实施例一和实施例二变体】
上述滤波装置实施例一和滤波装置实施例二是本申请的两种典型的滤波装置，在一些实施例对滤波装置实施例一或滤波装置实施例二进行变体，这些变体对滤波装置实施例一和滤波装置实施例二是相同的，下面以滤波装置实施例二讨论各种变体情况。
在滤波装置实施例二变体一中，对滤波装置实施例二中的各差模电感L2_i(i＝1,2,…,N)的两个线圈分别通过一组合电路接地，该组合电路可以由电阻、电感、电容或二极管组成，最优的方案为电容。图5A1是本申请的滤波装置实施例二变体一的示例的电路结构，其中各差模电感L2_i(i＝1,2,…,N)的两个线圈接分别通过电容C3_2i-1和C3_2i(i＝1,2,…,N)连接装置的接地端3_2i-1和3_2i，各接地端分别连接到地上。
在滤波装置实施例二变体二中，其中滤波装置的两个输入端分别串联一组合电路，用于隔离差分线路输入端的直流信号，该组合电路可以由电阻、电感、电容或二极管组成，最优的方案为电容。图5A2是本申请的滤波装置实施例二变体二的示例的电路结构，其中滤波装置的两个输入端1a和1b分别串联电容C1a和C1b。
在滤波装置实施例二变体三中，其中滤波装置的两个输出端分别串联一组合电路，用于隔离差分线路输出端的直流信号，该组合电路可以由电阻、电感、电容或二极管组成，最优的方案为电容。图5A3是本申请的滤波装置实施例二变体三的示例的电路结构，其中滤波装置的两个输出端2a和2b分别串联电容C2a和C2b。
在滤波装置实施例二变体四中，其中滤波装置的两个输入端与地之间分别联接一二极管或双向二极管，用于差分线路输入端的信号进行限幅，同时防静电。图5B1是本申请的滤波装置实施例二变体四示例的电路结构，其中装置的两个输入端1a和1b与地之间分别联接双向二极管D1b和双向二极管D1a。
在滤波装置实施例二变体五中，其中滤波装置的两个输出端与地之间分别联接一二极管或双向二极管，用于差分线路输出端的信号进行限幅，同时防静电。图5B2是本申请的滤波装置实施例二变体五的示例的电路结构，其中装置的两个输出端2a和2b与地之间分别联接双向二极管D2b和双向二极管D2a。
在滤波装置实施例二变体六中，其中滤波装置的两个输入端与地之间分别联接一差模电感的两个线圈之一，用于对差分线路输入端的第一共模信号进行阻抗匹配。图5C1是本申请的滤波装置实施例二变体六的示例的电路结构，其中装置的两个输入端1a和1b与地之间分别联接差模电感L2_0的一个线圈。
在滤波装置实施例二变体七中，其中滤波装置的两个输出端与地之间分别联接一差模电感的两个线圈之一，用于对差分线路的输出端的第二共模信号进行阻抗匹配。图5C2是本申请的滤波装置实施例二变体七示例的电路结构，其中滤波装置的两个输出端2a和2b与地之间分别联接差模电感L2_N+1的一个线圈。
在滤波装置实施例二变体八中，对滤波装置实施例二的各差模电感的接地端分别进行合并再分别接地，以简化电路，图5D1是本申请的滤波装置实施例二变体八的示例的电路结构图，对每个差模电感L2_i(i＝1,2,…,N)的两个线圈接地端合并为一个节点，编号分别为3_i，各接地端分别连接到地上。
在滤波装置实施例二变体九中，对滤波装置实施例二的各差模电感的接地端进行合并再接地，以简化电路，图5D2是本申请的滤波装置实施例二变体九的示例的电路结构图，对各差模电感L2_i(i＝1,2,…,N)的线圈接地端合并为一个节点，编号分别为3_1，再连接到地上。
在滤波装置实施例二变体十中，对滤波装置实施例二的各差模电感的接地端分别进行合并再通过电容分别接地，以简化电路，图5D3是本申请的滤波装置实施例二变体十的示例的电路结构图，对每个差模电感L2_i(i＝1,2,…,N)的两个线圈接地端合并为一个节点，各节点分别通过电容C3_i连接到编号为3_i的节点，再连接到地上。
在滤波装置实施例二变体十一中，对滤波装置实施例二的各差模电感的接地端进行合并再通过电容接地，以简化电路，图5D4是本申请的滤波装置实施例二变体十一的示例的电路结构图，对各差模电感L2_i(i＝1,2,…,N)的线圈接地端合并为一个节点，再通过电容C3_1连接到编号为3_1的节点上，再连接到地上。
在一些实施例中，把滤波装置实施例二的上述变体一至变体七进行相应的组合，包含其中任意的变体组合，图5E是本申请的滤波装置实施例二变体一至变体七组合的电路结构。
在一些实施例中，把本申请的滤波装置实施例变体八或变体十与变体二至变体七中至少一个变体进行组合，把本申请的滤波装置实施例变体九或变体十一与变体二至变体七中至少一个变体进行组合。
【一种滤波装置实施例三】
一种滤波装置实施例三包括两个串联的共模电感和在二者之间的差分线路的两个支路与地之间分别联接的两个电容，对共模信号形成了二级级联滤波，并且充分利用了多个电感和电容组合的频率特性，滤波效果较好。
图6A示出了一种滤波装置实施例三的电路结构，其包括顺序连接的共模电感L1_1、电容C3a、电容C3b和共模电感L1_2，当每个共模电感两个线圈中流过共模信号时产生的磁通量相互增强。其中，共模电感L1_1的两个线圈分别串联在滤波装置的输入端1a和1b；共模电感L1_2的两个线圈分别串联在共模电感L1_1的两个线圈与滤波装置的输出端2a和2b之间；电容C3a和电容C3b分别联接在两个共模电感之间的差分线路的两个支路与接地端3a和3b之间。
示例地，图6A中各共模电感的两个线圈绕向相同，设该两个线圈绕向均为顺时针方向或逆时针方向，则其两个线圈中的共模信号电流方向也均为是顺时针方向或逆时针方向。当各共模电感的两个线圈绕向不同，其共模信号电流方向也不同，设该两个线圈绕向一个为顺时针方向，另一个为逆时针，则其两个线圈中的共模信号电流方向一个是顺时针方向，另外一个为逆时针方向。
滤波装置实施例三的各元器件都是无源器件，滤波装置的输入端与输出端可以互换，而且工作原理相同，下面的描述均假设输入端在图的左边，输出端在图的右边。
下面先分析装滤波置实施例三对从左向右传播的第一共模信号的滤波效果，其中，共模电感L1_1、电容C3a和电容C3b组成第一级滤波模块C，共模电感L1_2和装置实施例三的负载组成第二级滤波模块D。装置中，电容值和电感值的选择要兼顾考虑多个电感和电容组合的频率特性。
示例地，设L1_1、L1_2参数相同，其共模电感值都是1μH；示例地，C3a和C3b参数相同，容值都是3pF；示例地，滤波装置实施例三的负载电阻为50Ω，上级驱动电路的输出电阻也为50Ω。图6B示出了基于上述示例的数值计算的滤波装置实施例三对第一共模信号的衰减，从图6B中可以看出在500Mhz时，滤波装置实施例三对第一共模信号的衰减值已经是65dB,在1个Ghz时已经超过80dB。
因为滤波装置实施例三是对称的，对从右向左传播的第二共模信号的滤波效果同对第一共模信号的滤波效果。
再分析滤波装置实施例三对从左向右传播的差模信号的滤波效果，示例地，再设L1_1、L1_2的差模电感值都是0.02μH；示例地，C3a和C3b容值都是3pF；示例地，滤波装置实施例三的负载电阻为50Ω，上级驱动电路的输出电阻也为50Ω，图6C示出了基于上述数值的计算的滤波装置实施例三对差模信号的衰减，从图6C可以看出装置实施例三对差模信号影响非常小。
滤波装置实施例三中各种参数设置是一种示例，实际使用根据具体场景进行设计。
综上，一种滤波装置实施例三通过两个串联的共模电感和在二者之间的差分线路与地之间分别联接的两个电容而组成的滤波装置，对共模信号形成了二级级联滤波， 并且充分利用了多个电感和电容组合的频率特性，对从差分信号发送电路发出的共模信号进行二级衰减，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号的负载引入的和传输过程引入的共模信号起作用，也进行二级衰减，衰减效果好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行了二级滤波，进一步提高差分线路信号的信噪比，还通过级联降低各共模信号进一步减少数据线缆上的噪声向外辐射。
【一种滤波装置实施例四】
一种滤波装置实施例四在滤波装置实施例三之后再顺序连接若干个相同的电路组合，该电路组合由一个共模电感和两个电容组成，对共模信号形成多级的级联滤波。
图7示出了滤波装置实施例四的结构，其在装置实施例三之后再连接N-1个共模电感和2(N-1)个电容组成。该N-1个共模电感顺序串联在差分线路上，分别编号为L1_3至L1_N+1，其中，每个共模电感的两个线圈分别串联在差分线路的一个支路上；该2(N-1)个电容联接在差分线路上，分别编号为C3_3至C3_2N(为了统一编号，图6A中电容C3a和C3b对应本图中的C3_1至C3_2)，其中，每两个共模电感之间的差分线路的每个支路与地之间联接一个电容。
示例地，图7中各共模电感的两个线圈绕向相同，设该两个线圈绕向均为顺时针方向或逆时针方向，则其两个线圈中的共模信号电流方向也均为是顺时针方向或逆时针方向。当各共模电感的两个线圈绕向不同，其共模信号电流方向也不同，设该两个线圈绕向一个为顺时针方向，另一个为逆时针，则其两个线圈中的共模信号电流方向一个是顺时针方向，另外一个为逆时针方向。
滤波装置实施例四的各元器件都是无源器件，滤波装置的输入端与输出端可以互换，而且工作原理相同，下面的描述均假设输入端在图的左边，输出端在图的右边。
下面先分析滤波装置实施例四对从左向右传播的第一共模信号的滤波效果，其中，共模电感L1_i(i＝1,2,…,N)、电容C3_2i-1(i＝1,2,…,N)和电容C3_2i(i＝1,2,…,N)组成第一级滤波模块C，共有N个第一级滤波模块C，一个共模电感L1_N+1和负载组成第二级滤波模块D，对第一共模信号实现N+1级的滤波，与滤波装置实施例三对比，增加了N-1个第一级滤模块C；并且由于电感和电容的增加，我们可以有更多的选择来调节电感和电容组合的频率特性，滤波效果在滤波装置实施例三的基础上进一步提高。
因为滤波装置实施例四是对称的，对从右向左传播的第二共模信号的滤波效果同对第一共模信号的滤波效果，即滤波效果在滤波装置实施例三的基础上进一步提高。
下面再分析滤波装置实施例四对从左向右传播的差模信号的滤波效果，其中，虽然增加了N-1个第一级滤波模块C，但第一级滤波模块C对差模信号的衰减较小，并且，我们也可以调节各电感和电容参数值，优化组合电路的整体频率特性，所以滤波装置实施例四对差模信号影响非常小。
综上，一种滤波装置实施例四通过至少三个串联的共模电感和在每两个相邻共模电感二者之间的差分线路与地之间联接的两个电容组成的滤波装置，对从差分信号发 送电路发出的共模信号进行多级衰减，衰减效果在滤波装置实施例三的基础上进一步提高，而且对差模信号影响小，在一个较宽的带宽内都较好地提高了差分线路信号的信噪比；同时对从差分信号的负载引入的和传输过程引入的共模信号起作用也进行多级衰减，衰减效果好，保护了差分信号发送电路。另外，还可以对平面噪声和通过线缆上耦合的共模信号也进行了多级滤波，进一步提高差分线路信号的信噪比，还通过级联降低各共模信号进一步减少数据线缆上的噪声向外辐射。
【一种滤波装置实施例三和装置实施例四的变体】
滤波装置实施例三和滤波装置实施例四也是本申请的两种典型的滤波装置，在一些实施例对滤波装置实施例三或滤波装置实施例四进行变体，这些变体对滤波装置实施例三和滤波装置实施例四是相同的，下面以滤波装置实施例四讨论各种变体情况。
在滤波装置实施例四变体一中，选择一个电阻和一个电容串联的组合电路代替滤波装置实施例四中各电容。
在滤波装置实施例四变体二中，在滤波装置的两个输入端与地之间分别联接一个电容或由一个电阻和一个电容串联的组合电路，实现输入阻抗匹配。
在滤波装置实施例四变体三中，在滤波装置的两个输出端与地之间分别联接一个电容或由一个电阻和一个电容串联的组合电路，实现输出阻抗匹配。
在滤波装置实施例四变体四中，在滤波装置的两个输入端与地之间分别联接一个二极管或双向二极管，实现限幅和防静电。
在滤波装置实施例四变体五中，在滤波装置的两个输出端与地之间分别联接一个二极管或双向二极管，实现限幅和防静电。
在一些实施例中，把上述各滤波装置实施例四的变体一至变体五进行相应的组合，图8示出了本申请的滤波装置实施例四变体一至变体五组合的电路结构。
【一种滤波装置实施例五】
一种滤波装置实施例五把一种滤波装置实施例一或一种滤波装置实施例一的变体或一种滤波装置实施例二或一种滤波装置实施例二的变体中的各共模电感封装一个器件里，其他电路保持不变。
【一种滤波装置实施例六】
一种滤波装置实施例六把一种滤波装置实施例三或一种滤波装置实施例三的变体或一种滤波装置实施例四或一种滤波装置实施例四的变体中的各共模电感封装一个器件里，其他电路保持不变。
图11示出了一种滤波装置实施例六的一个可能的实施方式，把一种滤波装置实施例三的各共模电感封装一个器件里，其他电路保持不变。
下面结合图9A1至图9C2介绍本申请的一种器件装置各实施例。
【器件实施例】
本申请还提供了器件实施例，把各滤波装置实施例的电路封装在一个器件里，实 现对共模信号的滤波，其包括器件实施例一、器件实施例二、器件实施例三、器件实施例四和各器件实施例的变体及变体组合。
器件实施例一对应于滤波装置实施例一，图9A1示出了器件实施例一的内部电路结构，其把图3A示出的滤波装置实施例一的共模电感L1_1和L1_2与差模电感L2_1封装在一个器件里。器件实施例一的输入端为1a和1b，输出端为2a和2b，接地端为3a和3b。
器件实施例一的优点同滤波装置实施例一，这里不再赘述。
器件实施例二对应于滤波装置实施例二，图9A2示出了器件实施例二的内部电路结构，其把图4A示出的滤波装置实施例二的各共模电感L1_i(i＝1,2,…,N+1)和差模电感L2_i(i＝1,2,…,N)封装在一个器件里。器件实施例二的输入端为1a和1b，输出端为2a和2b，有多个接地端，组成N组，分别为差模电感L2_i(i＝1,2,…,N)的线圈提供接地。
器件实施例二的优点同滤波装置实施例二，这里不再赘述。
器件实施例三对应于滤波装置实施例三，图9B1示出了器件实施例三的内部电路结构，其把图6A示出的滤波装置实施例三的共模电感L1_1和L1_2与电容C3a和电容C3b封装在一个器件里。器件实施例三的输入端为1a和1b，输出端为2a和2b，接地端为3a和3b。
器件实施例三的优点同滤波装置实施例三，这里不再赘述。
器件实施例四对应于滤波装置实施例四，图9B2示出了器件实施例四的内部电路结构，其把图7示出的滤波装置实施例四的各共模电感L1_i(i＝1,2,…,N+1)和2N个电容封装在一个器件里。器件实施例二的输入端为1a和1b，输出端为2a和2b，有多个接地端，组成N组，分别为各电容提供接地。
器件实施例四的优点同滤波装置实施例四，这里不再赘述。
各器件实施例不同于常规差分滤波器件的参数特征为：在其工作频率范围内，两个输入端与地之间、两个输出端与地之间对共模信号均为高阻状态。
在一些实施例中，还包括器件实施例的变体。
器件实施例一变体及组合，分别对应于滤波装置实施例一变体及组合，把滤波装置实施例一变体或组合中的各种共模电感、差模电感、各种单双向二极管、各种电容和各种电阻封装在一个器件里，对外连接方式与装置实施例一变体或组合对外连接方式相同。
器件实施例二变体及组合，分别对应于滤波装置实施例二变体及组合，把滤波装置实施例二变体或组合中的各种共模电感、差模电感、各种单双向二极管、各种电容和各种电阻封装在一个器件里，对外连接方式与装置实施例二变体或组合对外连接方式相同。
器件实施例三变体及组合，分别对应于滤波装置实施例三变体及组合，把滤波装置实施例三变体或组合中的各种共模电感、差模电感、各种单双向二极管、各种电容和各种电阻封装在一个器件里，对外连接方式与装置实施例三变体或组合对外连接方式相同。
器件实施例四变体及组合，分别对应于滤波装置实施例四变体及组合，把滤波装置实施例四变体或组合中的各种共模电感、差模电感、各种单双向二极管、各种电容和各种电阻封装在一个器件里，对外连接方式与装置实施例四变体或组合对外连接方式相同。
下面以器件实施例二变体为例，对器件实施例的变体或组合进行说明。器件实施例二变体一至十一对应于滤波装置实施例二变体一至十一，器件实施例二变体的组合对应滤波装置实施例二相应的变体的组合。
图9C1示出了器件实施例二变体一至七组合的示例的结构图，对应于滤波装置实施例二变体一至七组合，在器件实施例二的基础上，器件内部又增加了各元部件：各差模电感L2_i的接地电容C2i-1和C2i、输入电容C1a和C1b,输出电容C2a和C3b、阻抗匹配的差模电感L2_0及差模电感L2_N+1、输入限幅的二极管D1a和D1b，输出限幅的二极管D2a和D2b。
图9C2示出了器件实施例二变体十一的结构图，对应于滤波装置实施例二变体十一，对各差模电感L2_i(i＝1,2,…,N)的线圈接地端合并为一个节点，编号分别为3_1，再连接到地上。因此，整个器件实施例的接地端变为1个，简化对外连接方式。
本器件实施例均使用了无源部件，当其为对称电路时，输入端与输出端可以互换。
下面结合图10介绍本申请的一种传输装置实施例。
【传输装置实施例】
本申请还提供了传输装置实施例，用于传播差模信号，其包括差分线缆、差分线缆两端连接的第一装置，第一装置为一本申请的任一器件实施例或其变体或其变体组合，第一装置也可以是任一装置实施例或其变体或其变体组合。其中，差分线缆的屏蔽层可以不接地、通过电感接地、通过磁珠接地。
图10示出了一种传输装置实施例的应用场景的结构，其在图2的基础上增加了两个电感35，在差分线缆34的两端分别通过一个电感35接地。图10虚框内的差分线缆34、2个滤波电路32和2个电感35组成一个传输装置实施例。
公开技术中差分线缆34的屏蔽层接地，主要是为差分线缆34中的共模信号提供回流路径。差分线缆34中的共模信号可以在屏蔽层中感应出方向相反的电流，从而与共模信号叠加后，减少对外辐射。
当滤波电路32使用本申请的滤波装置任一实施例或其变体或其变体组合时，或当滤波电路32使用本申请的滤波器件任一实施例或其变体或其变体组合时，差分线缆34中的共模信号被衰减得非常小，那么差分线缆34上的主要辐射来源为地线耦合到差分线缆34的屏蔽层的共模噪声。此时把差分线缆34的屏蔽层和地之间用电感35隔离，降低地线耦合到差分线缆34的屏蔽层的共模噪声。
图10中差分线缆34的屏蔽层和地之间，还可以通过不接地或者用滤除对应频段的磁珠或其他滤波器件进行隔离。
注意，上述仅为本申请的较佳实施例及所运用技术原理。本领域技术人员会理解，本申请不限于这里所述特定实施例，对本领域技术人员来说能够进行各种明显的变 化、重新调整和替代而不会脱离本申请的保护范围。因此，虽然通过以上实施例对本申请进行了较为详细的说明，但是本申请不仅仅限于以上实施例，在不脱离本申请构思的情况下，还可以包括更多其他等效实施例，均属于本申请保护范畴。

Claims (10)

  1. 一种滤波装置，用于过滤差分线路中共模信号，其特征在于，包括:
    至少两个共模电感，所述共模电感为具有两个线圈的扼流圈，且每个所述共模电感的两个线圈在流过共模信号时产生的磁通量互相增强，其中，所述共模电感的一个线圈顺序串联在所述差分线路的一个支路上，各所述共模电感的另一个线圈按照所述顺序串联在所述差分线路的另一个支路上；
    至少一个差模电感，所述差模电感为具有两个线圈的扼流圈，所述差模电感的两个线圈在流过所述共模信号时产生的磁通量互相抵消，其中，在相邻的所述共模电感之间的所述差分线路的两个支路与地之间分别联接所述差模电感的一个线圈。
  2. 根据权利要求1所述滤波装置，其特征在于，还至少包括下列之一：
    在所述滤波装置的输入端与地之间连接的一个所述差模电感，其中，该所述差模电感的两个线圈分别联接在所述滤波装置的输入端的所述差分线路的两个支路与地之间，
    在所述滤波装置的输出端与地之间连接的一个所述差模电感，其中，该差模电感的两个线圈分别联接在所述滤波装置的输出端的所述差分线路的两个支路与地之间，
    在所述滤波装置的输入端的所述差分线路的两个支路与地之间分别联接的一个二极管，
    在所述滤波装置的输出端的所述差分线路的两个支路与地之间分别联接的一个二极管，
    在所述滤波装置的输入端的所述差分线路的两个支路分别串联的一个第三电路，所述第三电路至少包括下列之一：电感、电阻、电容、二极管，
    在所述滤波装置的输出端的所述差分线路的两个支路分别串联的一个所述第三电路。
  3. 根据权利要求2所述滤波装置，其特征在于，还包括：
    在各所述差模电感的两个线圈的接地端与地之间还联接的第四电路，所述第四电路至少包括下列之一：电感、电阻、电容、二极管。
  4. 一种滤波装置，用于过滤差分线路中共模信号，其特征在于，包括:
    至少两个共模电感，所述共模电感为具有两个线圈的扼流圈，且每个所述共模电感的两个线圈在流过共模信号时产生的磁通量互相增强，其中，所述共模电感的一个线圈顺序串联在所述差分线路的一个支路上，各所述共模电感的另一个线圈按照所述顺序串联在所述差分线路的另一个支路上；
    至少一个第一电路，所述第一电路包括两个第二电路，所述第二电路为电容或电容与电阻的串联电路，其中，在相邻的所述共模电感之间的所述差分线路的两个支路与地之间分别联接一个所述第二电路。
  5. 根据权利要求4所述滤波装置，其特征在于，还至少包括下列之一：
    在所述滤波装置的输入端的所述差分线路的两个支路与地之间分别联接的一个所述第二电路，
    在所述滤波装置的输出端的所述差分线路的两个支路与地之间分别联接的一个所述第二电路，
    在所述滤波装置的输入端的所述差分线路的两个支路与地之间分别联接的一个二极管，
    在所述滤波装置的输出端的所述差分线路的两个支路与地之间分别联接的一个二极管。
  6. 一种滤波器件，其特征在于，包括权利要求1或4所述滤波装置。
  7. 根据权利要求6所述滤波器件，其特征在于，
    当所述滤波器件包括权利要求1所述滤波装置时，还包括权利要求2或3所述滤波装置。
  8. 根据权利要求6所述滤波器件，其特征在于，
    当所述滤波器件包括权利要求4所述滤波装置时，还包括权利要求5所述滤波装置。
  9. 一种传输装置，其特征在于，包括：
    差分线缆；
    所述差分线缆两端连接基于权利要求1至3任一所述滤波装置或权利要求4至5任一所述滤波装置或权利要求6至8任一所述滤波器件。
  10. 根据权利要求9所述传输装置，其特征在于，在所述差分线缆的两端的屏蔽线与地之间包括下面任一连接方式：
    不连接；
    通过电感连接；
    通过磁珠连接。
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