CN109379543B - Digital television receiving equipment and radio frequency signal processing device thereof - Google Patents
Digital television receiving equipment and radio frequency signal processing device thereof Download PDFInfo
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- CN109379543B CN109379543B CN201811109515.XA CN201811109515A CN109379543B CN 109379543 B CN109379543 B CN 109379543B CN 201811109515 A CN201811109515 A CN 201811109515A CN 109379543 B CN109379543 B CN 109379543B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/41—Structure of client; Structure of client peripherals
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0237—High frequency adaptations
- H05K1/0245—Lay-out of balanced signal pairs, e.g. differential lines or twisted lines
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Abstract
The invention provides a digital television receiving device and a radio frequency signal processing device thereof, wherein the device comprises a printed circuit board, a first receiving circuit and a second receiving circuit, wherein an isolation channel is arranged on the printed circuit board to form a first area and a second area which are isolated from each other; a first common ground is formed in the first area, and a second common ground is formed in the second area; the first common ground and the second common ground are coupled through at least one ground isolation capacitor; the radio frequency terminal is arranged in the first area and is electrically connected with the first common ground; the input end of the single-end-to-differential conversion module is electrically connected with the output end of the radio frequency terminal, is arranged in the first area and is electrically connected with a first common ground; and the tuner is electrically connected with the output end of the single-end to differential module, is arranged in the second area and is electrically connected with a second common ground. The invention improves the anti-interference capability of the radio frequency signal and improves the transmission quality of the radio frequency signal.
Description
Technical Field
The present invention relates to the field of digital television technologies, and in particular, to a radio frequency signal processing apparatus and a digital television receiving device having the same.
Background
Digital signal receiving equipment such as a television, a set top box and the like receives cable television signals through an antenna, and the antenna is directly exposed to the external environment and can be influenced by thunder and lightning and the like; in addition, in order to eliminate the dangers such as spontaneous combustion and fire of the liquid crystal television caused by potential difference between the ground of the antenna and the ground of the main board, the antenna in the television is required to be isolated by an isolator in the national safety standard, and the isolation between the external antenna and the internal circuit of the main board of the television is realized.
The existing implementation scheme is that an external isolator is adopted, the isolator is plugged on a mainboard, and signals and the ground are isolated. However, the scheme of the external isolator has high cost, increases the transmission breakpoints of the radio frequency signals, affects the transmission quality of the radio frequency signals, and increases the length of the circuit board by the external isolator, which is not beneficial to miniaturization.
Another available implementation scheme is to integrate the function of an antenna isolator on a motherboard, and form the isolator by arranging elements such as an isolation capacitor on the motherboard to isolate the antenna ground from the motherboard ground. An external radio frequency signal is received by a radio frequency terminal, passes through circuits such as an isolator, a filter and the like, and is converted into a differential signal through a signal conversion circuit to enter a Tuner chip (Tuner IC). In the process of the radio frequency terminal passing through the isolator and the filter to the signal conversion circuit, the radio frequency signal is transmitted in a single end way, the single end signal transmission path is long, and is inevitably coupled with other signal lines on the mainboard, and is interfered by other high frequency signals on the mainboard, such as DDR (memory), Vbyone (image transmission digital interface), I2S (Inter-IC Sound, integrated circuit built-in audio bus) signals and the like, so that the electrical performance indexes (such as the minimum receiving level of digital television DTMB/DVB-C and the like) of the Tuner (Tuner) are influenced.
With the progress of the times, the integrated functions of a System On Chip (SOC) of a main board are more and more, the frequencies of a main frequency, a Double Data Rate (DDR) and the like are higher and higher, and the influence of high-frequency signals on a main board on the interference and indexes of Tuner becomes more and more obvious, and the main effects are as follows: 1. the Tuner is arranged close to the DDR, the higher the DDR frequency is, the more serious the electromagnetic interference (EMI) is, and the larger the interference on the Tuner is; 2. more and more components are integrated on the mainboard, crosstalk is generated between the radio-frequency signal single-end transmission part and some adjacent components, and the influence on the radio-frequency signal single-end transmission part is also generated; 3. for the multilayer mainboard with the common ground wire, the isolator, the filter, the signal conversion circuit, the Tuner and other components on the mainboard are all connected with the common ground of the mainboard, and common impedance coupling is formed among the components, so that the sensitivity of receiving signals of the Tuner is reduced if a certain layer is interfered.
In order to improve the anti-interference performance of the radio frequency signal, in the existing implementation scheme, modules such as electrostatic discharge and anti-electromagnetic interference are added to a single-end transmission part of the radio frequency signal, a shielding cover is added to a main board to suppress radiation interference, and grounding foam is added to the back of the main board to reduce capacitive crosstalk.
In view of the above, a new solution to the problem of Tuner interference is needed.
Disclosure of Invention
The invention aims to provide a radio frequency signal processing device and digital signal receiving equipment with the same, and solves the problem that radio frequency signals are easily interfered in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme:
according to an aspect of the present invention, there is provided a radio frequency signal processing apparatus comprising: the printed circuit board is provided with an isolation channel to form a first area and a second area which are isolated from each other, and the first area is surrounded by the isolation channel; a first common ground is formed in the first region, and a second common ground is formed in the second region; the first common ground and the second common ground are coupled by at least one ground isolation capacitance; the radio frequency terminal is used for receiving an external single-ended radio frequency signal, is arranged in the first area, and is electrically connected with the first common ground; the single-ended-to-differential module is arranged in the first area, is electrically connected with the first common ground, has an input end electrically connected with the output end of the radio frequency terminal, and is used for converting a single-ended radio frequency signal into a differential radio frequency signal; and the tuner is arranged in the second area, is electrically connected with the second common ground, has an input end electrically connected with the output end of the single-ended to differential module, and is used for receiving and processing differential radio-frequency signals.
Optionally, the ground isolation capacitor is disposed across the isolation trench, and two ends of the ground isolation capacitor are electrically connected to the first common ground and the second common ground, respectively.
Optionally, a core isolation capacitor is further disposed between the input end of the single-ended to differential module and the output end of the radio frequency terminal, and the core isolation capacitor is installed in the first region.
Optionally, the single-ended to differential module is a balun; the third pin of the balun is connected with the core wire isolation capacitor, the fourth pin of the balun is connected with a first common ground, and the first pin and the second pin of the balun are used as output ends of the single-ended differential-to-differential module to output differential signals.
Optionally, a blocking module is further disposed between the output end of the single-ended to differential module and the input end of the tuner; the output end of the blocking module is positioned in the second area.
Optionally, the first region is further provided with an impedance matching module, and the impedance matching module is electrically connected to the input end and the output end of the single-ended to differential conversion module, respectively, and is electrically connected to the first common ground.
Optionally, the impedance matching module includes a blocking capacitor, a resistor, and an inductor; one end of the blocking capacitor is connected with the input end of the single-end differential conversion module, and the other end of the blocking capacitor is connected with the first common ground; the resistor is connected with the output end of the single-end to differential module; one end of the inductor is connected with the output end of the single-ended to differential conversion module, and the other end of the inductor is connected with the first common ground.
Optionally, the isolation channel has a straight-line segment facing the tuner; the ground isolation capacitors are distributed on the straight line section part in two groups, and an interval is formed between the two groups of ground isolation capacitors; the blocking module is installed in the gap.
Optionally, in the ground isolation capacitors in each group, the capacitance of the ground isolation capacitor arranged closer to the blocking module is greater than or equal to the capacitance of another ground isolation capacitor adjacent to the ground isolation capacitor.
According to another aspect of the present invention, the present invention also provides a digital signal receiving apparatus comprising any one of the radio frequency signal processing devices described above.
According to the technical scheme, the invention has at least the following advantages and positive effects:
in the radio frequency signal processing device, after an external radio frequency signal is received by the radio frequency terminal, the external radio frequency signal is transmitted to the single-ended to differential module through the single-ended wiring, converted into a differential signal through the single-ended to differential module, and transmitted to the tuner for further processing in the form of the differential wiring. In the device, an isolation trench is provided on a printed circuit board to form a first region and a second region isolated from each other. The radio frequency terminal and the single-ended to differential module are mounted in a first region surrounded by the isolation channel, and a reference voltage is provided by a first common ground in the first region. And the second region is provided for mounting of the tuner and devices for subsequent processing of the radio frequency signal and the reference voltage is provided by a second common ground within the second region.
The first common ground is a high-voltage ground and is connected to a cable television network ground wire. The second common ground is a low-voltage ground of the main board and is connected with a power grid ground wire. The first common ground and the second common ground are physically separated through the separation channel, so that the dangers of spontaneous combustion, fire and the like of the liquid crystal display television, which are possibly caused by potential difference between the power grid ground wire and the cable television power grid ground wire, can be eliminated. By coupling the ground isolation capacitors on the isolation channels, on one hand, high-frequency noise in the second common ground can be prevented from directly flowing into the first common ground, so that the interference of high-frequency signals in the second area on the single-end routing part of radio frequency signals in the first area is eliminated; on the other hand, the problem of signal impedance discontinuity caused by sudden change of the radio frequency signal when the radio frequency signal is transmitted from the first area to the second area is reduced, and loss generated in the signal transmission process is reduced. In addition, the anti-interference capability of the single-ended routing part can be improved through ground isolation;
in the Tuner electrically connected with the second public ground and the subsequent processing process, the radio frequency signals adopt differential wiring, and the characteristic of strong anti-interference capability of the differential wiring is utilized, so that the resistance to the interference of Tuner caused by more and more main SOC integrated functions, higher and higher frequencies of main frequency, DDR and the like, high-frequency signals on the main board and the like is enhanced. In addition, modules such as electrostatic discharge and anti-electromagnetic interference are not required to be added, shielding cases are not required to be added on the mainboard to inhibit radiation interference, and structures such as grounding foam are added on the back of the mainboard. According to the technical scheme of the invention, the problem that the radio frequency signal is easily interfered by other high-frequency signals is effectively solved, and the transmission quality of the radio frequency signal is improved.
Drawings
Fig. 1 is a schematic block diagram of an alternative embodiment of the radio frequency signal processing apparatus of the present invention.
Fig. 2 is a schematic structural diagram of an alternative embodiment of the rf signal processing apparatus of the present invention.
Fig. 3 is a schematic circuit diagram of an alternative embodiment of the rf signal processing apparatus of the present invention.
The reference numerals are explained below: 1. a printed circuit board; 11. a first region; 111. a first common ground; 12. a second region; 121. a second common ground; 13. isolating the channel; 131. a first straight line segment; 132. a second straight line segment; 133. an arc segment; 2. an isolation unit; 3. a radio frequency terminal; 4. a signal conversion unit; 41. a single-end to differential module; 42. an impedance matching module; 43. a blocking module; 5. a tuner.
Detailed Description
Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive.
The invention provides a radio frequency signal processing device and digital signal receiving equipment with the same. The digital signal receiving device may be a television, a set-top box, etc. The radio frequency signal processing device is optionally integrated on the mainboard of the digital signal receiving equipment.
Briefly introduce the television rf signal processing principle:
the cable television network radio frequency signal received by the antenna is a high frequency signal, and the television SOC processing signal is an intermediate frequency signal, so that a Tuner chip (Tuner) is arranged to convert the high frequency signal into the intermediate frequency signal. The radio frequency signal is transmitted to the circuit board through the radio frequency terminal, and the radio frequency signal is a single-ended signal. Since the Tuner chip needs to input two-terminal signals (differential signals), a single-terminal to differential module (such as a balun circuit) is disposed between the rf terminal and the Tuner chip. The signal that the radio frequency terminal received is the high frequency signal, passes through isolator circuit module, single-ended commentaries on classics differential module, gets into the Tuner chip, and the Tuner chip exports intermediate frequency signal to SOC and demodulates under SOC's control, shows.
In order to eliminate the dangers of spontaneous combustion, fire and the like of the liquid crystal display television caused by potential difference between the power grid ground wire and the cable television power grid ground wire, an isolation channel is arranged on the circuit board to physically isolate the radio frequency signal input ground from the main board ground. The two isolated areas have reference grounds respectively, namely a high-frequency signal in front of the isolator refers to a high-voltage ground, and a high-frequency differential signal and an intermediate-frequency signal behind the isolator refer to a low-voltage ground. In the transmission process of signals, due to the fact that jump of the signals can be brought by the existence of the isolation channel, signal impedance is discontinuous, and large loss is generated in the transmission process of the signals, therefore, capacitors are placed on the isolation channel, effective transmission of useful signals in the frequency range of 40M to 855M is guaranteed, and loss is controlled within 2 dB.
In addition, the radio frequency signal entering the Tuner chip is a modulated multiplex signal of a plurality of frequency bands, the SOC and the Tuner chip can jointly generate a local oscillation signal according to the current frequency point requirement, the local oscillation signal is mixed with the input signal, so that a target signal of a matched channel can be selected from the multiplex signal, and the target signal is demodulated and displayed through the SOC.
The invention scheme is described in detail below with reference to the accompanying drawings:
referring to fig. 1, in an alternative embodiment of the present invention, the rf signal processing apparatus generally includes an rf terminal 3, an isolation unit 2, a signal conversion unit 4, and a tuner 5. The processing procedure of the radio frequency signal in the radio frequency signal processing device is roughly as follows: the high-frequency radio-frequency signal of the cable television network received by the antenna is input into the radio-frequency terminal 3, then the direct current and low-frequency signals are filtered by the isolation unit 2, the single-end to differential conversion, impedance matching and the like are carried out by the signal conversion unit 4, the differential radio-frequency signal is output by the signal conversion unit 4, and finally, the tuner 5 receives the differential radio-frequency signal and processes the differential radio-frequency signal into an intermediate-frequency signal to be output for a system chip of the digital signal receiving equipment to process and display the intermediate-frequency signal for a user to watch.
The transmission process of the radio frequency signal from the radio frequency terminal 3 to the signal conversion unit 4 through the isolation unit 2 is single-ended wire transmission, and the transmission process from the signal conversion unit 4 to the subsequent processing through the tuner 5 is differential wire transmission. It is worth noting that the signal transmitted by the single-ended trace is more easily interfered by the outside than the signal transmitted by the differential trace.
Specifically, fig. 2 is a schematic structural diagram of an alternative embodiment of the radio frequency signal processing apparatus of the present invention, fig. 3 is a schematic circuit diagram of the alternative embodiment of the radio frequency signal processing apparatus of the present invention, and referring to fig. 2 and fig. 3, the radio frequency signal processing apparatus is integrated on a printed circuit board 1, and an isolation unit 2, a radio frequency terminal 3, a signal conversion unit 4 and a tuner 5 are respectively mounted on the printed circuit board 1, wherein the isolation unit 2 includes a ground isolation capacitor, and the signal conversion unit 4 includes a single-ended differential module 41. The printed circuit board 1 is also used as a main board of the digital signal receiving device, and is used for mounting various functional devices such as a system chip (not shown), a memory (not shown) and the like, so as to realize related necessary functions of the digital signal receiving device.
As shown in fig. 2, in particular, the surface of the printed circuit board 1 is provided with an isolation trench 13, the surface of the printed circuit board 1 is divided into a first area 11 and a second area 12 which are isolated by the isolation trench 13, the first area 11 is surrounded by the isolation trench 13, and the second area 12 is located outside the isolation trench 13. The first region 11 is optionally located near a corner of the printed circuit board 1, and the area of the first region 11 is much smaller than the area of the second region 12. The second area 12 is provided with an interface (not shown) for installing the tuner 5, meanwhile, various functional devices such as a system chip (not shown) and a memory (not shown) are all installed in the second area 12, and a corresponding line (not shown) is arranged in the second area 12 to meet the electrical connection requirement among the devices. A second common ground 121 is formed in the second region 12, and the second common ground 121 is a low-voltage ground of the main board. The tuner 5 is electrically connected to the second common ground 121, and an input end of the tuner is electrically connected to an output end of the single-ended to differential module, and is configured to receive and process a differential radio frequency signal.
The first region 11 is provided with an interface (not shown) for mounting the rf terminal 3, the isolation unit 2, and the signal conversion unit 4, and a corresponding line (not shown) is formed to electrically connect the devices. The first area 11 is also formed with a first common ground 111, and the first common ground 111 is a high voltage ground and is connected to a cable television network ground. The high voltage is easily affected by external environment such as lightning, high voltage, etc. The rf terminal 3 is configured to receive an external single-ended rf signal and transmit the rf signal to the printed circuit board 1, where the rf signal is a single-ended signal, and the rf terminal 3 is electrically connected to the first common ground 111. The single-ended to differential module in the signal conversion unit 4 is electrically connected to the first common ground 111, and an input end of the single-ended to differential module is electrically connected to an output end of the rf terminal 3 for converting the single-ended rf signal into a differential rf signal.
Optionally, the voltage of the first common ground 111 is generally higher than the voltage of the second common ground 121. Wherein the first common ground 111 and the second common ground 121 are coupled through at least one ground isolation capacitor.
The isolation channel 13 is formed by removing a copper layer from the surface of the printed circuit board 1. The isolation channel 13 is contoured in a closed shape such that the first common ground 111 is physically isolated from the second common ground 121. The width of the isolation channel 13 is designed according to the requirement of the medium isolation level of the printed circuit board 1, for example, when the isolation voltage is required to be 800V, the width of the isolation channel 13 can be designed to be 1.5 mm. The dielectric isolation degrees of different printed circuit boards 1 are different, and the width of the isolation channel 13 is reasonably set according to actual requirements.
In this embodiment, the isolation channel 13 has a D-shaped contour, and includes a first straight line segment 131, two second straight line segments 132 vertically connected to two ends of the first straight line segment 131, and an arc segment 133 connected to the other ends of the two second straight line segments 132. The first straight segment 131 faces the interface in the second area 12 for the tuner 5 to be mounted, and the arc segment 133 faces the outer edge of the printed circuit board 1. The rf terminal 3 is mounted in the first region 11 at a position close to the arc segment 133 of the isolation channel 13. The ground of the rf terminal 3 is electrically connected to the first common ground 111, and the output end of the rf terminal 3 is electrically connected to a corresponding interface (not labeled) in the first region 11.
Optionally, referring to fig. 3, the isolation unit 2 includes ground isolation capacitors C1, C2, C3, C4, C5, C6 and a core isolation capacitor C7, so as to implement ground isolation and signal isolation.
The ground isolation capacitors C1-C6 are connected in parallel, and one end of each ground isolation capacitor C1-C6 is electrically connected with the first common ground 111, and the other end is electrically connected with the second common ground 121. The ground isolation capacitors C1-C6 are all high-voltage capacitors, have withstand voltage of not less than 1000V, and are used for coupling the first common ground 111 and the second common ground 121, so that the potential hazards of spontaneous combustion, fire and the like of digital signal receiving equipment, which are possibly caused by potential difference between the ground wires of the cable television network and the power grid, are eliminated. The capacitance of each of the local isolation capacitors C1-C6 is selected according to the requirements, and is optionally 4.7nF, 10nF, etc. According to practical situations, the number of the ground isolation capacitors C1-C6 can be increased or decreased as appropriate.
Referring to fig. 2, in the present embodiment, the ground isolation capacitors C1-C6 are all connected across the first straight line segment 131 of the isolation channel 13 and are arranged along the extending direction of the first straight line segment 131. The 6 ground isolation capacitors 131 are divided into two groups of three. The two sets of ground isolation capacitors are disposed on opposite sides of the midpoint of the first straight line segment 131 and have a spacing 1311. Two groups of ground isolation capacitors are symmetrically distributed, and three ground isolation capacitors of each group are equidistantly distributed. In the three ground isolation capacitors in each group, two ground isolation capacitors arranged adjacently may have the same capacitance, or the capacitance of the ground isolation capacitor closer to the midpoint of the first straight line segment 131 is larger than that of the other ground isolation capacitor. Namely: the ground isolation capacitor near the midpoint of the first straight line segment 131 has a larger capacitance value, and the ground isolation capacitor near the end of the first straight line segment 131 has a smaller capacitance value, so that the attenuation of the signal in the useful frequency band range is more uniform.
The core isolation capacitor C7 is also a high voltage capacitor with a withstand voltage of 3000V. One end of a core wire isolation capacitor C7 is electrically connected with the output end of the radio frequency terminal 3, a core wire isolation capacitor C7 is used for isolating the radio frequency signal of the radio frequency terminal 3, the capacitance of the core wire isolation capacitor C7 is smaller than that of the ground isolation capacitors C1-C6, the capacitance can be selected to be 470pF, the core wire isolation capacitor C7 is in a high-resistance state for direct current and low-frequency signals in the radio frequency signal, the direct current signal is prevented from damaging a chip, only a signal with higher frequency is allowed to pass, effective transmission of useful radio frequency signals of 40 MHz-1000 MHz is guaranteed, and the requirement that the signal loss of a frequency band of 40 MHz-1000 MHz is smaller than 2dB is met.
The signal conversion unit 4 converts the radio frequency signal transmitted by the radio frequency terminal 3 from a single-ended signal to a differential signal and outputs the differential signal to the second area 12, and the anti-interference capability of the radio frequency signal is improved by utilizing the advantage that the differential signal can resist external electromagnetic interference. Referring to fig. 3, in the present embodiment, the signal conversion unit 4 includes a single-ended to differential module 41.
The single-ended to differential module 41 realizes the function of converting a single-ended signal to a differential signal. In this embodiment, the single-ended to differential module 41 is composed of a balun L1, and the balun L1 converts an input single-ended signal into a differential signal and outputs the differential signal. A third pin of the balun L1 is used as an input end, is connected to the other end of the core isolation capacitor C7, is electrically connected to the output end of the radio frequency terminal 3 through the core isolation capacitor C7, and receives the single-ended radio frequency signal output by the radio frequency terminal 3; the fourth pin of the balun L1 is connected to the first common ground 111; the first pin and the second pin of the balun L1 are used as signal output terminals, and both output signals outwards, i.e. constitute differential signals.
The single-ended routing part is formed from the output end of the radio frequency terminal 3 to the input end of the balun L1, the radio frequency terminal 3 and the balun L1 are both electrically connected with the first common ground 111, the single-ended routing part is electrically isolated from the second common ground 121, a common coupling channel is not arranged between the single-ended routing part and a high-frequency signal source in the second area 12, the conducted interference of the high-frequency signal in the second area 12 to the single-ended routing part is avoided, the anti-interference capability is enhanced, and the transmission quality of the radio frequency signal is improved. Meanwhile, the input end of the balun L1 is directly electrically connected with the output end of the radio frequency terminal 3 through the core wire isolation capacitor C7, and the single-ended wiring part is shorter, so that the possibility of interference is reduced. In addition, the single-ended routing portion is located in the first area 11, and through the isolation of the isolation communication 13, the radiation interference of components (such as more and more main board SOC integration functions, higher and more main frequencies, DDR frequencies, and other high-frequency signals on the main board) in the second area 12 can be reduced, and the anti-interference capability of the single-ended routing portion is further improved.
In this embodiment, a balun L1 is used to realize the function of converting a single end into a differential end, and a balun L1 has a balanced characteristic of differential routing, which is beneficial to realizing impedance matching. Modules such as electrostatic discharge and anti-electromagnetic interference are not needed to be added, shielding covers are not needed to be added on the mainboard to inhibit radiation interference, and structures such as grounding foam are added on the back of the mainboard, so that the circuit structure is simple.
Optionally, in other embodiments, the single-ended signal may also be converted by building a circuit with components such as a resistor, a capacitor, and an inductor.
Optionally, the signal conversion unit 4 further includes an impedance matching module 42, and the impedance matching module 42 includes a first dc blocking capacitor C8, a resistor R1, and an inductor L3. One end of the first dc blocking capacitor C8 is connected to the third pin of the balun L1, and the other end of the first dc blocking capacitor C8 is connected to the first common ground 111. One end of the resistor R1 is connected to a first pin of the balun L1, and the other end of the resistor R1 is connected to a second pin of the balun L1. One end of the inductor L3 is connected to the second pin of the balun L1, and the other end of the inductor L3 is connected to the first common ground 111. The first direct current blocking capacitor C8 is connected to the input end of the balun L1 and grounded, the resistor R1 and the inductor L3 are connected to the output end of the balun L1 and grounded, and the impedance value of the balun L1 is adjusted to be consistent with the characteristic impedance of the transmission line of the input end and the output end respectively, so that impedance matching is formed at the input end and the output end, reflection on the transmission line in the signal transmission process is reduced, and transmission loss is reduced.
Optionally, the signal converting unit 4 further includes a dc blocking module 43, where the dc blocking module 43 includes a second dc blocking capacitor C10 and a third dc blocking capacitor C11, one end of the second dc blocking capacitor C10 is connected to the first pin of the balun L1, and one end of the third dc blocking capacitor C11 is connected to the second pin of the balun L1. The other end of the second dc blocking capacitor C10 and the other end of the third dc blocking capacitor C11, which serve as the output end of the signal conversion unit 4, are electrically connected to the input end of the tuner 5, so as to transmit the rf differential signal to the tuner 5. The second blocking capacitor C10 and the third blocking capacitor C11 have the voltage resistance of not less than 1000V, form two-stage blocking with the first blocking capacitor C8, have the high voltage resistance capability, improve the anti-static capability, do not need to additionally arrange an anti-static unit in the radio frequency signal processing device, and simplify the circuit structure.
Referring to fig. 2, in the embodiment, the positions of the second dc blocking capacitor C10 and the third dc blocking capacitor C11 on the printed circuit board 1 are located in the space 1311 between the two sets of ground isolation capacitors, and the other end of the second dc blocking capacitor C10 and the other end of the third dc blocking capacitor C11 extend out of the first straight line 131 of the isolation channel 13 and are located in the second region 12, so as to facilitate connection with the tuner 5.
Based on the above embodiments, the technical solution of the present invention has at least the following advantages:
the first common ground and the second common ground are physically separated through the separation channel, so that the dangers of spontaneous combustion, fire and the like of the liquid crystal display television caused by potential difference between the power grid ground wire and the cable television power grid ground wire can be eliminated. By coupling the ground isolation capacitors on the isolation channels, on one hand, high-frequency noise in the second common ground can be prevented from directly flowing into the first common ground, so that the interference of high-frequency signals in the second area on the single-end routing part of radio frequency signals in the first area is eliminated; on the other hand, the problem of signal impedance discontinuity caused by sudden change of the radio frequency signal when the radio frequency signal is transmitted from the first area to the second area is reduced, and loss generated in the signal transmission process is reduced. In addition, the anti-interference capability of the single-ended routing part can be improved through ground isolation;
in the Tuner electrically connected with the second public ground and the subsequent processing process, the radio frequency signals adopt differential wiring, and the characteristic of strong anti-interference capability of the differential wiring is utilized, so that the resistance to the interference of Tuner caused by more and more main SOC integrated functions, higher and higher frequencies of main frequency, DDR and the like, high-frequency signals on the main board and the like is enhanced. In addition, modules such as electrostatic discharge and anti-electromagnetic interference are not required to be added, shielding cases are not required to be added on the mainboard to inhibit radiation interference, and structures such as grounding foam are added on the back of the mainboard. According to the technical scheme of the invention, the problem that the radio frequency signal is easily interfered by other high-frequency signals is effectively solved, and the transmission quality of the radio frequency signal is improved.
The embodiment of the present invention further provides a digital signal receiving apparatus, which includes any one of the foregoing radio frequency signal processing devices, and please refer to the foregoing embodiment for specific description, which will not be repeated herein. When the radio frequency signal processing device is applied to digital signal receiving equipment, the printed circuit board is used as a mainboard of the digital signal receiving equipment, the second common ground is used as a mainboard low-voltage ground, the tuner, the system chip, other functional devices and the like are electrically connected with the second common ground, and through the isolation of the isolation channel and the coupling of the ground isolation capacitor, a high-frequency signal cannot interfere with a single-ended wiring part which is electrically connected with the first common ground, so that the anti-interference capability of the digital signal receiving equipment is improved, and the equipment can stably run.
While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.
Claims (10)
1. A radio frequency signal processing apparatus, comprising:
the printed circuit board is provided with an isolation channel to form a first area and a second area which are isolated from each other, and the first area is surrounded by the isolation channel; a first common ground is formed in the first region, and a second common ground is formed in the second region; the first common ground and the second common ground are coupled by at least one ground isolation capacitance;
the radio frequency terminal is used for receiving an external single-ended radio frequency signal, is arranged in the first area, and is electrically connected with the first common ground;
the single-ended-to-differential module is arranged in the first area, is electrically connected with the first common ground, has an input end electrically connected with the output end of the radio frequency terminal, and is used for converting a single-ended radio frequency signal into a differential radio frequency signal;
and the tuner is arranged in the second area, is electrically connected with the second common ground, has an input end electrically connected with the output end of the single-ended to differential module, and is used for receiving and processing differential radio-frequency signals.
2. The radio frequency signal processing device according to claim 1, wherein the ground isolation capacitor is disposed across the isolation trench, and both ends of the ground isolation capacitor are electrically connected to the first common ground and the second common ground, respectively.
3. The radio frequency signal processing device according to claim 1, wherein a core isolation capacitor is further disposed between the input terminal of the single-ended-to-differential module and the output terminal of the radio frequency terminal, and the core isolation capacitor is installed in the first region.
4. The radio frequency signal processing device according to claim 3, wherein the single-ended to differential module is a balun; the third pin of the balun is connected with the core wire isolation capacitor, the fourth pin of the balun is connected with a first common ground, and the first pin and the second pin of the balun are used as output ends of the single-ended differential-to-differential module to output differential signals.
5. The radio frequency signal processing device according to any one of claims 1 to 4, wherein a dc blocking module is further disposed between the output terminal of the single-ended to differential conversion module and the input terminal of the tuner; the output end of the blocking module is positioned in the second area.
6. The radio frequency signal processing device according to claim 5, wherein the first region is further provided with an impedance matching module, and the impedance matching module is electrically connected to the input terminal and the output terminal of the single-ended to differential conversion module, respectively, and electrically connected to the first common ground.
7. The radio frequency signal processing device according to claim 6, wherein the impedance matching module comprises a dc blocking capacitor, a resistor and an inductor; one end of the blocking capacitor is connected with the input end of the single-end differential conversion module, and the other end of the blocking capacitor is connected with the first common ground; the resistor is connected with the output end of the single-end to differential module; one end of the inductor is connected with the output end of the single-ended to differential conversion module, and the other end of the inductor is connected with the first common ground.
8. The radio frequency signal processing device according to claim 5, wherein the isolation channel has a straight-line section facing the tuner; the ground isolation capacitors are distributed on the straight line section part in two groups, and an interval is formed between the two groups of ground isolation capacitors; the blocking module is installed in the gap.
9. The apparatus according to claim 8, wherein a capacitance of a ground isolation capacitor disposed closer to the dc blocking module among the plurality of ground isolation capacitors in each group is greater than or equal to a capacitance of another ground isolation capacitor adjacent thereto.
10. A digital television receiving device comprising a radio frequency signal processing apparatus as claimed in any one of claims 1 to 9.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811109515.XA CN109379543B (en) | 2018-09-21 | 2018-09-21 | Digital television receiving equipment and radio frequency signal processing device thereof |
| PCT/CN2019/091291 WO2020057190A1 (en) | 2018-09-21 | 2019-06-14 | Digital television receiver and radio frequency signal processing device thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201811109515.XA CN109379543B (en) | 2018-09-21 | 2018-09-21 | Digital television receiving equipment and radio frequency signal processing device thereof |
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| CN109379543A CN109379543A (en) | 2019-02-22 |
| CN109379543B true CN109379543B (en) | 2021-03-23 |
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| WO (1) | WO2020057190A1 (en) |
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| CN109379543B (en) * | 2018-09-21 | 2021-03-23 | 海信视像科技股份有限公司 | Digital television receiving equipment and radio frequency signal processing device thereof |
| CN112153812B (en) * | 2019-06-28 | 2022-09-13 | 深圳迈瑞生物医疗电子股份有限公司 | Circuit board and AED equipment |
| CN113365005B (en) * | 2020-03-06 | 2023-06-09 | 格科微电子（上海）有限公司 | Implementation method of image sensor column processing module blocking capacitor |
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| CN101820508A (en) * | 2009-02-26 | 2010-09-01 | 上海融创名睿微电子有限公司 | Radio frequency front end circuit of single-ended transfer difference of digital mobile television receiver tuner |
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| Publication number | Publication date |
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| CN109379543A (en) | 2019-02-22 |
| WO2020057190A1 (en) | 2020-03-26 |
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Address after: 266000, No. 218, Bay Road, Qingdao economic and Technological Development Zone, Shandong Applicant after: Hisense Visual Technology Co., Ltd. Address before: 266555 Qingdao economic and Technological Development Zone, Shandong, Hong Kong Road, No. 218 Applicant before: QINGDAO HISENSE ELECTRONICS Co.,Ltd. |
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