Protective radio frequency signal receiving circuit with high voltage isolation function
By using components such as current absorption tubes and varistors in the radio frequency signal receiving circuit, the problem of DC blocking capacitor damage caused by high voltage surges is solved, thereby improving the safety and reliability of the circuit and ensuring the safe use of the set-top box.
Patent Information
- Application Number
- CN202520206260.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2035-02-10
AI Technical Summary
In existing radio frequency signal receiving circuits, high-voltage surge currents or leakage voltages can be directly applied to DC blocking capacitors, causing them to be damaged or explode and burn, posing a safety hazard.
A first current absorption tube and a second current absorption tube (such as a TVS tube) are used to absorb high-voltage surge current, and a varistor and a PTC thermistor protect the DC blocking capacitor, forming dual protection against current and voltage to ensure that the capacitor is not damaged.
It effectively absorbs surge voltage, prevents damage to DC blocking capacitors, reduces the risk of circuit combustion, improves the safety and reliability of RF signal receiving circuits, and ensures the lifespan and safety performance of the set-top box.
Smart Images
Figure CN223772073U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of radio frequency signal transmission technology, and in particular to a protective radio frequency signal receiving circuit with high voltage isolation. Background Technology
[0002] Since 2000, China has gradually transitioned from analog to digital television. Cable digital television set-top boxes based on HFC coaxial cable transmission have seen particularly rapid development, and are still used by hundreds of millions of users. To fully utilize and improve the data transmission capacity of HFC coaxial cables, the backbone networks between cities primarily use fiber optic transmission. In urban areas, this is divided into headends or backends in residential communities. Through HFC network equipment such as photoelectric conversion workstations and various branch terminals, the signals are converted into coaxial signals before being delivered to the digital television set-top boxes in users' homes.
[0003] Because these HFC network devices use a centralized power supply method, the power supply for all devices within the same coaxial cable network comes from a single centralized power supply device, and then the voltage and current are transmitted through the coaxial cable. Unsafe voltages or currents from the same power supply device can easily crosstalk to the user's set-top box through the coaxial cable, posing a potential electrical safety issue and causing damage to the set-top box. Furthermore, if the user's coaxial cable network wiring is not up to standard, it is easy for external leakage voltages to be introduced into the set-top box through the coaxial cable, leading to damage.
[0004] The existing RF signal input module of the set-top box simply adds a DC blocking capacitor between the core wire and the ground wire. Although this achieves the purpose of isolating DC current, there is a problem: if the user's coaxial cable introduces high voltage, such as the high voltage generated by lightning, the high voltage surge current will pass through the core wire or ground wire of the coaxial cable and be directly applied to the DC blocking capacitor. If the power of multiple high voltage surges or currents exceeds the load of the capacitor, it can easily cause damage to the DC blocking capacitor. In extreme cases, it can cause the capacitor to explode and burn, causing safety problems. Utility Model Content
[0005] The purpose of this utility model is to address the problem in existing radio frequency signal receiving circuits where high voltage surge current or leakage voltage is directly applied to the DC blocking capacitor, causing the DC blocking capacitor to be easily damaged, explode, burn, and become unsafe. This utility model provides a protective radio frequency signal receiving circuit with high voltage isolation, including: a signal input module and a signal receiving module.
[0006] The first core wire of the signal input module is connected to the second core wire of the signal receiving module; a first DC blocking capacitor is provided at one end of the second core wire connected to the first core wire, and the other end serves as the radio frequency signal output terminal.
[0007] The first outer conductor of the signal input module is connected to the second outer conductor of the signal receiving module and the ground, forming a first grounding terminal; a second DC blocking capacitor is provided at one end of the second outer conductor connected to the first outer conductor, and the other end is connected to the set-top box ground, forming a second grounding terminal;
[0008] The first core wire is connected to the first ground terminal through a first current absorption tube; the radio frequency signal output terminal of the second core wire is connected to the second ground terminal through a second current absorption tube.
[0009] The protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, by setting a first current absorption tube and a second current absorption tube, which are low-capacitance, instantaneous high voltage surge current absorption tubes, will conduct when the voltage of the first core wire exceeds the selected specifications of the first or second current absorption tube. This will connect the current generated by the high voltage surge in the first core wire to the first grounding terminal, or connect the current generated by the high voltage surge in the second core wire to the second grounding terminal, thereby conducting the high voltage surge to the earth and the set-top box ground respectively. This achieves the function of absorbing surge voltage, preventing the high voltage surge voltage from being applied to the first DC blocking capacitor, thus protecting the first DC blocking capacitor from being damaged, reducing the unsafe factors of circuit explosion and combustion, and improving the safety of the radio frequency signal receiving circuit in transmitting electrical signals to the user.
[0010] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, a varistor is further provided between the second outer conductor and the second grounding terminal; the two ends of the varistor are respectively connected in parallel to the two ends of the second DC blocking capacitor.
[0011] As a preferred embodiment of this utility model, the varistor is connected between the first and second outer conductors of the signal. With the first outer conductor connected to the ground and the second outer conductor connected to the set-top box ground, when there is a high-voltage surge voltage between these two grounding terminals, such as a lightning strike, the voltage exceeds the selected specification voltage of the varistor. The varistor immediately conducts and discharges, thereby ensuring that the voltage across the second DC blocking capacitor does not exceed the designed limit voltage, avoiding damage or even explosion and combustion of the second DC blocking capacitor, and further improving the safety of the radio frequency signal receiving circuit in transmitting electrical signals to the user.
[0012] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, the rated voltage of the varistor is less than or equal to the selection voltage of the second DC blocking capacitor.
[0013] As a preferred embodiment of this utility model, it can achieve a better protection effect for the second DC blocking capacitor.
[0014] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, a first PTC thermistor is connected in series between the first core wire and the second core wire; and a second PTC thermistor is connected in series between the first outer conductor and the second outer conductor.
[0015] As a preferred embodiment of this utility model, by setting a first PTC thermistor and a second PTC thermistor, when the current input from the first core wire to the second core wire exceeds the selected current specification of the first PTC thermistor, or when the current input from the first outer conductor to the second outer conductor exceeds the selected current specification of the second PTC thermistor, after the temperature rises to a certain level, the first PTC thermistor and the second PTC thermistor will immediately increase in temperature, thereby reducing the current at the front end of the first DC blocking capacitor and the second DC blocking capacitor, preventing a large current from being input to the signal receiving module, and thus protecting the set-top box signal receiving circuit from being damaged or even burned.
[0016] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, the selection current of the first PTC thermistor and / or the second PTC thermistor is more than 1.5 times the actual maximum current value.
[0017] As a preferred embodiment of this utility model, the above-mentioned configuration can improve the matching degree between the PTC thermistor and the circuit, resulting in higher sensitivity and further enhancing protection performance.
[0018] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, the second DC blocking capacitor includes multiple capacitor units, and the multiple second DC blocking capacitors are connected in parallel with each other and have different capacitance values.
[0019] As a preferred embodiment of this utility model, by setting the second DC blocking capacitor to include multiple capacitor units connected in parallel with different capacitance values, shielding is achieved to allow various useful radio frequency signals to pass through while blocking DC voltage, thereby enhancing the applicability and anti-interference performance of the circuit.
[0020] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, the first current absorption tube and / or the second current absorption tube are TVS tubes.
[0021] As a preferred embodiment of this utility model, a TVS diode is used. The Chinese meaning of TVS diode is transient voltage suppressor diode, which can change the high impedance at both ends to low impedance in a very short time, absorb surge power of up to several kilowatts, and has high absorption capacity for surge voltage or current, thus enhancing protection performance.
[0022] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, the capacitance value of the first DC blocking capacitor and / or the second DC blocking capacitor is 0.001uF to 0.01uF; and the selection voltage range of the first DC blocking capacitor and / or the second DC blocking capacitor is 500V to 2000V.
[0023] As a preferred embodiment of this utility model, by setting the capacitance range of the first DC blocking capacitor and / or the second DC blocking capacitor, the circuit can achieve efficient and accurate transmission of radio frequency signals in set-top box signal reception, and has a better DC isolation effect. Furthermore, the higher the selected voltage range value, the better the damage resistance, but the space occupied and the cost of the device layout are also higher. This utility model, through the above-mentioned preferred setting of the voltage range, has a low cost and further improves economic efficiency.
[0024] Preferably, in the protective radio frequency signal receiving circuit with high voltage isolation described in this utility model, the selection voltage of the first current absorption tube is less than or equal to the selection voltage of the first DC blocking capacitor; the selection voltage of the second current absorption tube is less than or equal to the selection voltage of the first DC blocking capacitor.
[0025] As a preferred embodiment of this utility model, by setting the selection voltage of the first current absorption tube and the second current absorption tube to be the same as or slightly lower than that of the first DC blocking capacitor and the second DC blocking capacitor, a better protection effect can be achieved.
[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:
[0027] 1. When the voltage of the first core wire exceeds the selected specifications of the first or second current absorption tube, the first or second current absorption tube will conduct, connecting the current generated by the high voltage surge in the first core wire to the first grounding terminal, or connecting the current generated by the high voltage surge in the second core wire to the second grounding terminal, thereby conducting the high voltage surge to the earth and the set-top box ground respectively, thus achieving the function of absorbing surge voltage, preventing the high voltage surge voltage from being applied to the first DC blocking capacitor, protecting the first DC blocking capacitor from being damaged, reducing the unsafe factors of circuit explosion and combustion, and improving the safety of the radio frequency signal receiving circuit in transmitting electrical signals to the user;
[0028] 2. It not only achieves the function and performance requirements of effectively receiving radio frequency signals, but also effectively prevents damage to the set-top box or even combustion caused by lightning strikes, high voltage, high current leakage, etc. It has the characteristics of low cost, good performance and easy design. While ensuring that the set-top box meets the requirements of indicators, performance and cost, it improves the service life and safety performance of the set-top box. Attached Figure Description
[0029] Figure 1This is a connection diagram of this utility model;
[0030] Icons: 10, Earth; 11, First core wire; 12, First outer conductor; 13, First grounding terminal; 20, Set-top box ground; 21, Second core wire; 22, RF signal output terminal; 23, Second outer conductor; 24, Second grounding terminal. Detailed Implementation
[0031] The present invention will now be described in detail with reference to the accompanying drawings.
[0032] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.
[0033] Example 1:
[0034] like Figure 1 As shown, this utility model discloses a protective radio frequency signal receiving circuit with high voltage isolation, comprising: a signal input module and a signal receiving module; a first core wire 11 of the signal input module is connected to a second core wire 21 of the signal receiving module; a first DC blocking capacitor is provided at one end of the second core wire 21 connected to the first core wire 11, wherein, Figure 1 The first DC blocking capacitor shown is C1; the other end of the second core wire 21 serves as the radio frequency signal output terminal 22; the first outer conductor 12 of the signal input module is connected to the second outer conductor 23 of the signal receiving module and the ground 10 respectively, forming a first grounding terminal 13; a second DC blocking capacitor is provided at one end of the second outer conductor 23 connected to the first outer conductor 12, wherein the second DC blocking capacitor includes Figure 1 As shown in Figures C2 to Cn; the other end of the second outer conductor 23 is connected to the set-top box ground 20, forming the second grounding terminal 24; the first core wire 11 is connected to the first grounding terminal 13 through the first current absorption tube; the radio frequency signal output terminal 22 of the second core wire 21 is connected to the second grounding terminal 24 through the second current absorption tube, wherein the first current absorption tube is as follows: Figure 1 As shown in the diagram, Q1, the second flow absorption tube is as follows: Figure 1 Q2 as shown;
[0035] refer to Figure 1 As shown, the signal input module is Figure 1 The signal input section shown refers to the signal receiving module. Figure 1The signal receiving section is shown. The first core wire 11 or the second core wire 21 is understood as the inner conductor of the coaxial cable, mainly used to transmit the current of the radio frequency signal. The signal current mainly flows along the core wire, such as the transmission of RF signals. The first outer conductor 12 and the second outer conductor 23 mainly serve to shield and provide a return path. In terms of shielding, they can prevent external electromagnetic interference from entering the cable and also prevent the signal inside the cable from radiating into the external space. Specifically, the signal input module of this utility model is a coaxial cable, which is responsible for RF signal input; the signal output terminal of the signal receiving module is responsible for signal output.
[0036] In this invention, specifically, the first current absorption tube and / or the second current absorption tube are TVS diodes. A TVS diode, or transient voltage suppressor diode, can rapidly reduce its impedance when subjected to a high-energy instantaneous impact, while simultaneously absorbing a large current and clamping the voltage between its two ends to a predetermined value, thereby ensuring that subsequent circuit components are protected from damage caused by the high-energy transient impact.
[0037] In this invention, specifically, a varistor is also provided between the second outer conductor 23 and the second grounding terminal 24. The second grounding terminal 24 can be understood as one end connected to the set-top box ground 20. The varistor is as follows: Figure 1 As shown in the diagram, the two ends of the varistor are connected in parallel to the two ends of the second DC blocking capacitor. More specifically, the rated voltage of the varistor is less than or equal to the selection voltage of the second DC blocking capacitor. (Reference) Figure 1 As shown, RN is a varistor, for example, a varistor with a voltage rating of ZOV. The varistor is connected in series between the ground 10 of the signal input module and the set-top box ground 20 of the signal receiving module. For example, one pin of RN is connected to the ground wire of the signal input module, and the other pin is connected to the ground wire of the signal receiving module. When there is a high voltage surge between the ground 10 and the set-top box ground 20, such as a lightning strike, the voltage exceeds the selected specification voltage of RN. RN immediately conducts and discharges, thereby ensuring that the voltage across the second DC blocking capacitor does not exceed the designed limit voltage, avoiding damage or even explosion and combustion of the second DC blocking capacitor.
[0038] Specifically, a first PTC thermistor is connected in series between the first core wire 11 and the second core wire 21; the first PTC thermistor is as follows: Figure 1 As shown in RP1; a second PTC thermistor is connected in series between the first outer conductor 12 and the second outer conductor 23; the second PTC thermistor is as follows: Figure 1RP2 is shown. It should be noted that the first PTC thermistor and the second PTC thermistor are respectively understood as semiconductor resistors with a positive temperature coefficient. When the temperature exceeds a certain threshold, the resistance value will increase sharply. For example, when the current in the core wire or the outer conductor ground wire exceeds the selected specification current of RP1 or RP2, the temperature of RP1 or RP2 will rise. After the temperature rises to a certain level, the resistance of RP1 or RP2 will immediately increase, reducing the current and realizing overcurrent protection and other functions.
[0039] Specifically, the selection current of the first PTC thermistor and / or the second PTC thermistor is more than 1.5 times the actual maximum current value; it should be noted that the actual maximum current value is understood as the maximum current value of the radio frequency signal receiving circuit of this utility model under actual operating conditions, which can be obtained according to the actual operating conditions.
[0040] Specifically, the second DC blocking capacitor includes multiple capacitor units, such as capacitor units C2, C3...Cn. Multiple second DC blocking capacitors are connected in parallel with each other and have different capacitance values, where n represents the (n-1)th capacitor unit. The number of n can be selected according to the signal frequency of the actual circuit.
[0041] Specifically, the capacitance value of the first DC blocking capacitor and / or the second DC blocking capacitor is 0.001uF to 0.01uF; the selection voltage range of the first DC blocking capacitor and / or the second DC blocking capacitor is 500V to 2000V.
[0042] Specifically, the selection voltage of the first current absorption tube is less than or equal to the selection voltage of the first DC blocking capacitor; the selection voltage of the second current absorption tube is less than or equal to the selection voltage of the first DC blocking capacitor. It should be noted that the terms "first" and "second" in this invention are used for clarity of description only and are not explained with specific numerical values.
[0043] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A protective radio frequency signal receiving circuit with high voltage isolation, characterized by, The utility model relates to a signal input module and signal receiving module, and a signal transmission method thereof. The first core wire (11) of the signal input module is connected to the second core wire (21) of the signal receiving module; one end of the second core wire (21) connected to the first core wire (11) is provided with a first direct-current blocking capacitor, and the other end serves as a radio frequency signal output end (22). The first outer conductor (12) of the signal input module is connected to the second outer conductor (23) and the ground (10) of the signal receiving module respectively to form a first grounding end (13); one end of the second outer conductor (23) connected to the first outer conductor (12) is provided with a second direct-current blocking capacitor, and the other end is connected to a set-top box ground (20) to form a second grounding end (24). The first core wire (11) is connected to the first grounding end (13) through a first current absorption tube; the radio frequency signal output end (22) of the second core wire (21) is connected to the second grounding end (24) through a second current absorption tube. A pressure-sensitive resistor is further arranged between the second outer conductor (23) and the second grounding end (24); the two ends of the pressure-sensitive resistor are connected to the two ends of the second direct-current blocking capacitor respectively.
2. The shielded radio frequency signal receiving circuit with isolation of high voltage according to claim 1, characterized in that, The specification voltage of the pressure-sensitive resistor is less than or equal to the selected voltage of the second direct-current blocking capacitor.
3. The shielded radio frequency signal receiving circuit with isolation of high voltage according to claim 2, characterized in that, A first PTC thermistor is connected in series between the first core wire (11) and the second core wire (21); a second PTC thermistor is connected in series between the first outer conductor (12) and the second outer conductor (23).
4. The shielded RF signal receiving circuit according to any one of claims 1 to 3, wherein The selected current of the first PTC thermistor and / or the second PTC thermistor is more than 1.5 times of the actual maximum current value.
5. The shielded radio frequency signal receiving circuit with isolation of high voltage according to claim 4, characterized in that, The second direct-current blocking capacitor comprises a plurality of capacitor units, and the plurality of second direct-current blocking capacitors are connected in parallel and have different capacitances.
6. The shielded radio frequency signal receiving circuit with high voltage isolation according to claim 1, wherein, The first current absorption tube and / or the second current absorption tube is a TVS tube.
7. The shielded radio frequency signal receiving circuit with high voltage isolation according to claim 1, wherein, The capacitance value of the first direct-current blocking capacitor and / or the second direct-current blocking capacitor is 0.001uF-0.01uF; the selected voltage range of the first direct-current blocking capacitor and / or the second direct-current blocking capacitor is 500V-2000V.
8. The shielded radio frequency signal receiving circuit with high voltage isolation according to claim 1, wherein, The selected voltage of the first current absorption tube is less than or equal to the selected voltage of the first direct-current blocking capacitor; the selected voltage of the second current absorption tube is less than or equal to the selected voltage of the first direct-current blocking capacitor.
9. The shielded radio frequency signal receiving circuit with high voltage isolation according to claim 1, wherein,