Filter circuit, signal transmission circuit and electronic equipment

Abstract

The invention provides a filter circuit, a signal transmission circuit and electronic equipment. According to the filter circuit, the signal transmission line and the filter line are connected in parallel, and a resonant circuit structure is formed by using the capacitor on the signal transmission line and the inductor on the filter line, so that the filter circuit can realize efficient filtering at a specific resonant frequency, the loss of signals in the transmission process is reduced, and the signal transmission quality is improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a filtering circuit, a signal transmission circuit and an electronic device. Background Art

[0002] With the rapid development of electronic technology, high-speed transmission technology is needed in many fields such as communications, computers, consumer electronics, etc. to meet the requirements of high-speed signal transmission. High-speed transmission technology is a high-speed point-to-point serial channel transmission technology. Compared with traditional point-to-point transmission technology, high-speed point-to-point serial channel transmission technology can achieve higher transmission frequency and transmission rate.

[0003] However, when using high-speed point-to-point serial channel transmission technology to transmit signals at high speed, the signal will suffer from insertion loss during the high-speed transmission process, causing the signal strength to gradually weaken, seriously affecting the effective transmission distance and quality of the signal. Summary of the invention

[0004] In view of this, the present application provides a filtering circuit, a signal transmission circuit and an electronic device to improve the problem of serious signal quality attenuation during high-speed signal transmission.

[0005] The technical solution adopted by this application to solve the above technical problems is:

[0006] In a first aspect, an embodiment of the present application provides a filtering circuit, comprising at least one filtering unit, wherein the filtering unit comprises:

[0007] A signal transmission line, wherein a capacitor is connected to the signal transmission line;

[0008] At least one filter circuit is connected in parallel to the input end of the capacitor on the signal transmission circuit, an inductor is connected to the filter circuit, and one end of the inductor away from the signal transmission circuit is grounded;

[0009] Wherein, the filtering circuit satisfies the following formula:

[0010] f=1 / [2π√(L×C)];

[0011] f is the resonant frequency at which the filter circuit generates resonance, L is the equivalent inductance value of the inductor on at least one of the filter lines, and C is the equivalent capacitance value of the capacitor on at least one of the filter lines.

[0012] In some embodiments of the present application, one of the filter circuits is connected in parallel to the input end of the capacitor, and another of the filter circuits is connected in parallel to the output end of the capacitor.

[0013] In some embodiments of the present application, a plurality of the filter units are connected in series.

[0014] In some embodiments of the present application, the current value of the filter circuit is equal to the current value of the signal transmission circuit, and the current direction of the filter circuit is opposite to the current direction of the signal transmission circuit.

[0015] In some embodiments of the present application, the value range of the inductance is 0.1nH to 5nH, the value range of the capacitance is 1pF to 5pF, and the resonant frequency range of the filter circuit is 1GHZ to 6.3GHZ.

[0016] In some embodiments of the present application, when the resonant frequency range of the filter circuit is 3.25 GHZ to 6.25 GHZ, the capacitance value of the capacitor is 2 pF, and the inductance value of the inductor is 2 nH.

[0017] In a second aspect, an embodiment of the present application provides a signal transmission circuit, including:

[0018] A timing controller, used for sending a control signal;

[0019] The filter circuit as described in the first aspect, wherein the input end of the filter circuit is connected to the output end of the timing controller;

[0020] A signal receiver is connected to the output end of the filter circuit and is used to receive the control signal.

[0021] In some embodiments of the present application, the positive output terminal of the timing controller is connected to the positive input terminal of the signal receiver through one of the filter circuits; the negative output terminal of the timing controller is connected to the negative input terminal of the signal receiver through another of the filter circuits.

[0022] In some embodiments of the present application, the capacitance value and the inductance value in the filter circuit connected to the positive output terminal of the timing controller are respectively the same as the capacitance value and the inductance value in the filter circuit connected to the negative output terminal of the timing controller.

[0023] In a third aspect, an embodiment of the present application provides an electronic device, comprising the filtering circuit as described in the first aspect or the signal transmission circuit as described in the second aspect.

[0024] In summary, due to the adoption of the above technical solution, this application has at least the following beneficial effects:

[0025] The embodiments of the present application provide a filtering circuit, a signal transmission circuit and an electronic device, by connecting the signal transmission line and the filtering line in parallel, and using the capacitor on the signal transmission line and the inductor on the filtering line to form a resonant circuit structure, so that the filtering circuit can achieve efficient filtering at a specific resonant frequency, reduce the loss of the signal during transmission, and improve the quality of signal transmission. In detail, by reasonably designing the parameters of the inductor and the capacitor so that they satisfy the resonant frequency formula of f=1 / [2π√(L×C)], at the resonant frequency, the capacitive reactance of the capacitor and the inductive reactance of the inductor cancel each other, so that the energy loss of the signal when passing through the filtering unit is greatly reduced, thereby improving the signal transmission efficiency. And it presents a higher impedance to interference signals of other frequencies, thereby effectively filtering out clutter and improving the purity of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the structure of a filter circuit provided in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a signal transmission circuit provided in an embodiment of the present application.

[0028] Figure 3 A schematic diagram of the insertion loss simulation of the signal transmission circuit provided in the embodiment of the present application and the traditional signal transmission circuit;

[0029] Figure 4 A schematic diagram of input and output voltages of a signal transmission circuit provided in an embodiment of the present application;

[0030] Figure 5 A schematic diagram of input and output voltages of a conventional signal transmission circuit;

[0031] Figure 6 A schematic diagram of an eye diagram simulation of a signal transmission circuit provided in an embodiment of the present application;

[0032] Figure 7 This is a schematic diagram of the eye diagram simulation of a traditional signal transmission circuit.

[0033] Description of reference numerals:

[0034] 1. Filter circuit; 11. Signal transmission line; 111. Capacitor; 12. Filter line; 121. Inductor; 2. Timing controller; 3. Signal receiver. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0036] In the description of this application, it should be understood that the words "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0038] See also Figure 1 The embodiment of the present application provides a filter circuit 1, comprising at least one filter unit. The filter unit comprises a signal transmission line 11 and at least one filter line 12. A capacitor 111 is connected to the signal transmission line 11, the filter line 12 is connected in parallel to the input end of the capacitor 111 on the signal transmission line 11, an inductor 121 is connected to the filter line 12, and one end of the inductor 121 away from the signal transmission line 11 is grounded to form a resonant structure of the inductor 121 and the capacitor 111.

[0039] For example, when actually manufacturing a circuit board, the signal transmission line 11 can be made of copper foil on a printed circuit board, and the capacitor 111 and the inductor 121 are soldered at corresponding positions by surface mounting technology. One end of the capacitor 111 is connected to the signal transmission line 11, and the other end is suspended for connecting other components; one end of the inductor 121 is connected to the signal transmission line 11 where the input end of the capacitor 111 is located, and the other end is grounded.

[0040] Among them, the filter circuit 12 satisfies the following formula:

[0041] f=1 / [2π√(L×C)];

[0042] f is the resonant frequency of the filter circuit 1 generating resonance, L is the equivalent inductance 121 value of the inductor 121 on at least one filter line 12 , and C is the equivalent capacitance 111 value of the capacitor 111 on at least one filter line 12 .

[0043] When the circuit meets the resonant frequency formula, in the resonant state, the inductive reactance of the inductor 121 and the capacitive reactance of the capacitor 111 cancel each other out. At the resonant frequency f, the impedance of the circuit is minimum, and the signal can pass smoothly without being affected by the inductive reactance and the capacitive reactance. For signals of other frequencies, since the resonant condition is not met, they will be hindered by a large impedance, thereby achieving a filtering function. For example, when the inductor 121 is set to 2nH and the capacitor 111 is set to 2pF, according to the resonant frequency formula, the resonant frequency can be calculated to be 3.98GHZ, that is, near this frequency, the circuit has the smallest transmission loss for the signal and the strongest ability to suppress interference signals of other frequencies, which is conducive to reducing insertion loss and improving signal transmission quality.

[0044] The technical solution provided by the present application forms a resonant circuit structure by connecting the signal transmission line 11 and the filter line 12 in parallel, and using the capacitor 111 on the signal transmission line 11 and the inductor 121 on the filter line 12, so that the filter circuit 1 can achieve efficient filtering at a specific resonant frequency f, reduce the loss of the signal during transmission, and improve the quality of signal transmission. In detail, by reasonably designing the parameters of the inductor 121 and the capacitor 111, so that they meet the resonant frequency formula of f=1 / [2π√(L×C)], at the resonant frequency, the capacitive reactance of the capacitor 111 and the inductive reactance of the inductor 121 cancel each other, so that the energy loss of the signal when passing through the filter unit is greatly reduced, thereby improving the signal transmission efficiency. And it presents a higher impedance to interference signals of other frequencies, thereby effectively filtering out clutter and improving the purity of the signal.

[0045] In some embodiments, the value range of the inductor 121 is 0.1nH to 5nH, the value range of the capacitor 111 is 1pF to 5pF, and the resonant frequency range of the filter circuit 1 is 1GHZ to 6.3GHZ. Different values ​​of the inductor 121 and the capacitor 111 will change the resonant frequency, thereby adapting to different signal filtering requirements. In subsequent experiments, when the resonant frequency range of the filter circuit 1 is 3.25GHZ to 6.25GHZ, the inductor 121 is 2nH, and the capacitor 111 is 2pF. It can be obtained that when the resonant frequency rises from 3.25GHZ to 6.25GHZ, the filter circuit 1 provided in the present application is used in a signal transmission circuit. Compared with the traditional signal transmission circuit, the insertion loss is reduced by about 2.1dB, which will be described in detail in the subsequent experimental simulation process. In other embodiments, the value of the inductor 121 and the value of the capacitor 111 are mainly selected according to the frequency of the circuit in the actual situation, and are not limited here.

[0046] In some embodiments, two filter circuits 12 are respectively connected in parallel to the input end and the output end of the capacitor 111. When there are two filter circuits 12, they are respectively connected in parallel to the input end and the output end of the capacitor 111. Compared with one filter circuit 12 connected in parallel to the input end of the capacitor 111, the filtering effect can be further optimized, and the signal is resonantly processed from both ends of the capacitor 111, and the screening ability of the specific frequency signal and the suppression ability of the interference signal are enhanced. The two filter circuits 12 are equivalent to constructing two resonant circuits at both ends of the capacitor 111. For the signal of a specific frequency, the two resonant circuits work together, so that the signal can be transmitted more accurately in a resonant state when passing through the capacitor 111, reducing the distortion and loss of the signal. Assuming that the inductance 121 and the capacitor 111 of the two filter circuits 12 have the same parameters, at the resonant frequency, the inductive reactance and the capacitive reactance of the two filter circuits 12 cancel each other, so that the voltage drop at both ends of the capacitor 111 is mainly determined by the signal itself, rather than caused by the reactance characteristics of the capacitor 111. This reduces the loss of the signal during the energy storage and release process at the capacitor 111, further improving the signal transmission efficiency. At the same time, for interference signals of non-resonant frequency, the two filter lines 12 perform impedance matching on the two ends of the capacitor 111, making it more difficult for it to pass through the capacitor 111, thereby improving the filtering circuit 1's ability to filter out clutter.

[0047] In some embodiments, there are multiple filter units, and multiple filter units are connected in series. The filter unit can be a case where the inductor 121 in a filter line 12 is connected in parallel with the input end of the capacitor 111 in the signal transmission line 11, or it can be a case where two filter lines 12 are connected in parallel to the input end and output end of the capacitor 111 respectively. Multiple filter units are connected in series, and the signal passes through each filter unit in turn. Each filter unit can perform resonant filtering on a signal of a specific frequency. In a system that needs to filter multiple signals of different frequencies, different filter units can be designed to have different resonant frequencies. The first filter unit can filter out low-frequency interference signals, the second filter unit can optimize the processing of intermediate frequency signals, and the third filter unit can suppress high-frequency noise, etc. From the perspective of signal transmission, the series filter units can gradually purify the signal. The first filter unit first removes a part of the interference signal, so that the quality of the signal entering the second filter unit is improved, and so on. After passing through multiple filter units, the purity of the signal is greatly improved. Moreover, since each filter unit works based on the resonance principle, the loss of the signal at its respective resonant frequency is small, and the signal will not be excessively attenuated due to too many filtering links. From the perspective of the frequency response characteristics of the overall circuit, multiple filter units connected in series can construct more complex and accurate frequency selection characteristics to adapt to various complex signal environment requirements. In addition, if multiple filter units have the same parameters, that is, they filter the same frequency signal, then multiple filter units are equivalent to forming a multi-order filter structure, filtering the frequency signal multiple times, further reducing insertion loss and improving signal transmission efficiency and signal transmission quality.

[0048] In some embodiments, the current value of the filter circuit 12 is equal to the current value of the signal transmission circuit 11, and the current direction of the filter circuit 12 is opposite to the current direction of the signal transmission circuit 11. Based on Kirchhoff's current law of the circuit, in a parallel circuit, the total current flowing into the node is equal to the total current flowing out of the node. At the parallel node of the filter circuit 12 and the signal transmission circuit 11, part of the current of the signal transmission circuit 11 flows into the filter circuit 12, and part continues to be transmitted along the signal transmission circuit 11. Since the filter circuit 12 is grounded through the inductor 121 to form a resonant circuit, when the circuit is in a resonant state, energy is exchanged between the inductor 121 and the capacitor 111, so that the current in the filter circuit 12 cooperates with the current in the signal transmission circuit 11 to achieve optimized transmission of the signal. Exemplarily, at resonance, the current in the filter circuit 12 will store part of the energy in the signal transmission circuit 11 in the form of magnetic field energy in the inductor 121, and then feed it back to the signal transmission circuit 11 through the capacitor 111 in the form of electric field energy, thereby reducing the energy loss of the signal during transmission to the external circuit.

[0049] See also Figure 2 , an embodiment of the present application also provides a signal transmission circuit, including a timing controller 2, a signal receiver 3 and the filter circuit 1 described in any of the above embodiments. Among them, the timing controller 2 is used to send a control signal, the input end of the filter circuit 1 is connected to the output end of the timing controller 2, and the signal receiver 3 is connected to the output end of the filter circuit 1 for receiving the control signal. Exemplarily, in the actual circuit layout, the timing controller 2, the filter circuit 1 and the signal receiver 3 can be installed on the same PCB board and electrically connected through the traces on the PCB. The output pin of the timing controller 2 is connected to the signal input pin of the filter circuit 1 through a wire, and the output pin of the filter circuit 1 is then connected to the input pin of the signal receiver 3. By using the filter circuit 1 to optimize the transmission channel of the signal transmission circuit, the quality and transmission efficiency of the signal transmission are improved, and from a side view, it is also beneficial to reduce the cost of the circuit board. For example, when a traditional signal transmission circuit and the signal transmission circuit of the present application need to achieve the same signal transmission effect, the traditional signal transmission circuit needs to be manufactured using a high-speed board, while the signal transmission circuit of the present application has improved signal transmission effect due to the setting of the filter circuit 1 and does not rely on a high-speed board. Therefore, it can be manufactured using an ordinary board, thereby achieving the effect of reducing costs. The board cost can be reduced by more than 30%.

[0050] Furthermore, the positive output terminal of the timing controller 2 is connected to the positive input terminal of the signal receiver 3 through a filter circuit 1; the negative output terminal of the timing controller 2 is connected to the negative input terminal of the signal receiver 3 through another filter circuit 1, and the signal transmission circuit at this time is a differential signal transmission circuit. In differential signal transmission, the symmetry of the positive and negative signals is very important. That is, setting the filter circuit 1 in the positive and negative lines respectively is conducive to ensuring that the positive and negative signals are subjected to the same filtering treatment during the transmission process, reducing signal distortion and imbalance. For example, in high-speed data transmission, the differential signal can effectively resist common-mode noise interference, and the symmetrical filter circuit 1 can better maintain this anti-interference ability and improve the reliability and accuracy of signal transmission.

[0051] Furthermore, the capacitor 111 value and the inductor 121 value in the filter circuit 1 connected to the positive output end of the timing controller 2 are respectively the same as the capacitor 111 value and the inductor 121 value in the filter circuit 1 connected to the negative output end of the timing controller 2, which is more conducive to maintaining the differential characteristics of the signal, ensuring that the positive and negative signals receive the same filtering processing during transmission, and reducing signal distortion and imbalance.

[0052] Based on the structure of the signal transmission circuit, the following experimental simulation comparison of the signal transmission circuit is carried out:

[0053] First, the specific parameters are adjusted and determined. The frequency of the transmission circuit increases from 2GHZ to 20GHZ, the inductor 121 in the filter circuit 1 is set to 2nH, and the capacitor 111 is set to 2pF. Then, the insertion loss and channel impulse step response of the signal transmission circuit provided by the present application and the traditional signal transmission circuit are compared.

[0054] See also Figure 3 , Line A represents the change in insertion loss in the signal transmission circuit provided by the present application, and Line B represents the change in insertion loss in the traditional signal transmission circuit. It can be seen from the figure that when the frequency is 3.25GHZ, the insertion loss in the signal transmission circuit of the present application is -3.038dB, and the insertion loss in the traditional signal transmission circuit is -3.130dB. When the frequency is 6.25GHZ, the insertion loss in the signal transmission circuit of the present application is -4.341dB, and the insertion loss in the traditional signal transmission circuit is -6.496dB. It can be seen that when the frequency is 6.25GHZ, the insertion loss in the signal transmission circuit of the present application is reduced by more than 2.1dB.

[0055] See also Figure 4 and Figure 5 , Figure 4 A schematic diagram of input and output voltages of a signal transmission circuit provided in an embodiment of the present application, Figure 5 The schematic diagram of the input and output voltages of a traditional signal transmission circuit. It can be seen that the output voltage of the traditional signal transmission circuit is significantly lower than the output voltage of the signal transmission circuit of the present application, indicating that the signal transmission circuit of the present application has good channel impulse step response characteristics. When the input signal changes rapidly (such as a step change), the signal transmission circuit in the present application can process and transmit the signal quickly and stably, reducing signal distortion. When processing step signals, traditional circuits may cause signal distortion due to circuit delays, oscillations and other problems. This distortion will cause signal energy dispersion and ultimately reduce the output voltage.

[0056] See also Figure 6 and Figure 7 , Figure 6 The eye diagram simulation diagram of the signal transmission circuit provided in the embodiment of the present application is shown in FIG. Figure 7 This is a schematic diagram of eye diagram simulation of a traditional signal transmission circuit. It can be seen that under the same test conditions, the eye diagram height of the signal transmission circuit of the present application is approximately twice the eye diagram height of the traditional signal transmission circuit, which verifies that the signal transmission circuit of the present application has a higher signal amplitude than the traditional signal transmission circuit, reduces the attenuation of the signal during the transmission process, and improves the signal quality.

[0057] The embodiment of the present application also provides an electronic device, including the filter circuit 1 described in any of the aforementioned embodiments or the signal transmission circuit described in any of the aforementioned embodiments. In the electronic device, the filter circuit 1 or the signal transmission circuit can be integrated on the mainboard of the device and work in conjunction with other electronic components. For example, in a display device, the filter circuit 1 can filter the received and transmitted signals to improve the quality of the signals, and the signal transmission circuit is responsible for controlling the transmission path and timing of the signals. The filter circuit 1 can optimize the high-speed bus signals on the mainboard to improve the stability and speed of data transmission.

[0058] It should be noted that in order to simplify the description of the embodiments of the present application and thus help understand one or more embodiments, in the above description of the embodiments, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this method of expression does not mean that the features required by the object of the present application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

Claims

1. A filter circuit, characterized in that: The method comprises at least one filtering unit, wherein the filtering unit comprises: A signal transmission line, wherein a capacitor is connected to the signal transmission line; At least one filter circuit is connected in parallel to the input end of the capacitor on the signal transmission circuit, an inductor is connected to the filter circuit, and one end of the inductor away from the signal transmission circuit is grounded; Wherein, the filtering circuit satisfies the following formula: f=1 / [2π√(L×C)]; f is the resonant frequency at which the filter circuit generates resonance, L is the equivalent inductance value of the inductor on at least one of the filter lines, and C is the equivalent capacitance value of the capacitor on at least one of the filter lines.

2. The filter circuit according to claim 1, characterized in that: One of the filter lines is connected in parallel to the input end of the capacitor, and the other filter line is connected in parallel to the output end of the capacitor.

3. The filter circuit according to claim 1 or 2, characterized in that: A plurality of the filter units are connected in series.

4. The filter circuit according to claim 1 or 2, characterized in that: The current value of the filter circuit is equal to the current value of the signal transmission circuit, and the current direction of the filter circuit is opposite to the current direction of the signal transmission circuit.

5. The filter circuit according to claim 1 or 2, characterized in that: The value range of the inductance is 0.1nH to 5nH, the value range of the capacitance is 1pF to 5pF, and the resonant frequency range of the filter circuit is 1GHZ to 6.3GHZ.

6. The filter circuit according to claim 5, characterized in that: When the resonant frequency range of the filter circuit is 3.25 GHZ to 6.25 GHZ, the capacitance value of the capacitor is 2 pF, and the inductance value of the inductor is 2 nH.

7. A signal transmission circuit, characterized in that: include: A timing controller, used for sending a control signal; The filter circuit according to any one of claims 1 to 6, wherein the input end of the filter circuit is connected to the output end of the timing controller; A signal receiver is connected to the output end of the filter circuit and is used to receive the control signal.

8. The signal transmission circuit according to claim 7, characterized in that: The positive output terminal of the timing controller is connected to the positive input terminal of the signal receiver through one of the filter circuits; the negative output terminal of the timing controller is connected to the negative input terminal of the signal receiver through another of the filter circuits.

9. The signal transmission circuit according to claim 8, characterized in that: The capacitance value and the inductance value in the filter circuit connected to the positive output terminal of the timing controller are respectively the same as the capacitance value and the inductance value in the filter circuit connected to the negative output terminal of the timing controller.

10. An electronic device, characterized in that: The method comprises the filtering circuit according to any one of claims 1 to 6 or the signal transmission circuit according to any one of claims 7 to 9.

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