Signal amplification filter circuit supporting four paths of TUNERs

Abstract

The utility model relates to the technical field of set top boxes, in particular to a signal amplification filter circuit supporting four paths of TUNERs, which is applied to the set top box and utilizes the characteristics of a first-stage common-mode anti-interference circuit, a first second-stage common-mode anti-interference circuit and a second second-stage common-mode anti-interference circuit. Signals amplified by an LAN signal amplification circuit are decomposed into two paths of signals, the two paths of signals are decomposed into four paths of signals through a first secondary common-mode anti-interference circuit and a second secondary common-mode anti-interference circuit, and every two paths of signals are converted into four paths of signals through the action of the first secondary common-mode anti-interference circuit and the second secondary common-mode anti-interference circuit. The four TUNER radio frequency signal input ends only need one LAN signal amplification circuit, so that the problem of mutual interference when multiple TUNER radio frequency signal input ends work at the same time is solved; therefore, the signal receiving stability of the product is improved. And meanwhile, the layout space of PCB elements in the set top box is also reduced, so that the product can be miniaturized.

Description

Technical Field

[0001] The utility model relates to the technical field of set-top boxes, in particular to a signal amplifying and filtering circuit supporting 4-channel TUNERs. Background Art

[0002] As users' demands for set-top boxes become higher and higher, many set-top boxes on the market have built-in multi-channel TUNER; the emergence of multi-channel TUNER set-top boxes solves the problem that users can watch programs at the current frequency while recording programs at different frequencies. Multi-channel TUNER set-top boxes usually require that each TUNER front end must have an independent signal amplifier to solve the problem of receiving stable signals and not interfering with each other when multiple TUNERs work at the same time. Utility Model Content

[0003] The utility model solves the defects and shortcomings of the prior art and provides a signal amplification and filtering circuit supporting 4-channel TUNER without mutual interference of signals.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is a signal amplification and filtering circuit supporting 4-way TUNER, and the signal amplification and filtering circuit is applied to a set-top box, including a radio frequency signal input pin, an FM filtering circuit, a WIFI filtering circuit, a LAN signal amplification circuit, a primary common-mode anti-interference circuit, a first secondary common-mode anti-interference circuit, a second secondary common-mode anti-interference circuit, a first TUNER radio frequency signal input terminal, a second TUNER radio frequency signal input terminal, a third TUNER radio frequency signal input terminal and a fourth TUNER radio frequency signal input terminal, the radio frequency signal input pin is used to transmit an external antenna signal to the FM filtering circuit, and the output terminal of the FM filtering circuit is connected to the WIFI The input end of the WIFI filter circuit is electrically connected, the output end of the WIFI filter circuit is electrically connected to the input end of the LAN signal amplifying circuit, the output end of the LAN signal amplifying circuit is electrically connected to the output end of the first common-mode anti-interference circuit, the output end of the first common-mode anti-interference circuit is electrically connected to the input ends of the first and second common-mode anti-interference circuits, respectively, the output ends of the first and second common-mode anti-interference circuits are electrically connected to the first TUNER RF signal input end and the second TUNER RF signal input end, respectively, the output ends of the second and second common-mode anti-interference circuits are electrically connected to the third TUNER RF signal input end and the fourth TUNER RF signal input end, respectively.

[0005] Furthermore, the FM filter circuit includes a first inductor, a second inductor, a third inductor, a first capacitor, a second capacitor and a third capacitor; the first inductor, the second inductor and the third capacitor are connected in series, one end of which is connected to the RF signal input pin, and the other end is grounded; one end of the first capacitor is connected to the RF signal input pin, and the other end is connected to the common end of the first inductor and the second inductor; the second capacitor and the third inductor are connected in parallel, one end of which is connected to the common end of the first inductor and the second inductor, and the other end is connected to the WIFI filter circuit.

[0006] Furthermore, the WIFI filter circuit includes a fourth inductor, a fifth inductor and a fourth capacitor; the fourth inductor, the fifth inductor and the fourth capacitor are connected in series, one end is connected to the common end of the second capacitor and the third inductor, and the other end is grounded.

[0007] Furthermore; the LAN signal amplification circuit includes a radio frequency amplifier, a sixth inductor, a seventh inductor, a fifth capacitor, a sixth capacitor, a first resistor and a power supply circuit; the second pin of the radio frequency amplifier is electrically connected to the power supply circuit; one end of the seventh inductor is electrically connected to the first pin of the radio frequency amplifier, and the other end is electrically connected to the power supply circuit; one end of the sixth inductor is connected to the common end of the fourth inductor and the fifth inductor, and the other end is connected to the sixth pin of the radio frequency amplifier; the fifth pin of the radio frequency amplifier is grounded; one end of the sixth capacitor is connected to the fourth pin of the radio frequency amplifier, and the other end is grounded; one end of the first resistor is connected to the fourth pin of the radio frequency amplifier, and the other end is connected to the GPIO interface.

[0008] Furthermore, the first-level common-mode anti-interference circuit includes a first common-mode inductor, a seventh capacitor, an eighth inductor and a second resistor; the second end of the first common-mode inductor is connected to the fifth capacitor; one end of the seventh capacitor is grounded, and the other end is connected to the second end of the first common-mode inductor; the fourth end of the first common-mode inductor is connected to the fifth capacitor; the second resistor and the eighth inductor are connected in series, one end is connected to the third end of the first common-mode inductor, and the other end is connected to the first end of the first common-mode inductor.

[0009] Further; the first secondary common-mode anti-interference circuit includes a second common-mode inductor, an eighth capacitor, a third resistor, a ninth inductor, a fourth resistor and a fifth resistor; the fourth end of the second common-mode inductor is connected to the third end of the first common-mode inductor; the second end of the second common-mode inductor is connected to the third end of the first common-mode inductor; one end of the eighth capacitor is grounded, and the other end is connected to the common end of the second end and the fourth end of the second common-mode inductor; the third end of the second common-mode inductor is connected to the first TUNER RF signal input end; the first end of the second common-mode inductor is connected to the second TUNER RF signal input end; the third resistor and the ninth inductor are connected in series, one end is connected to the third end of the second common-mode inductor, and the other end is connected to the first end of the common-mode inductor; one end of the fourth resistor is grounded, and the other end is connected to the first TUNER RF signal input end; one end of the fifth resistor is grounded, and the other end is connected to the second TUNER RF signal input end.

[0010] Further; the second secondary common-mode anti-interference circuit includes a third common-mode inductor, a ninth capacitor, a sixth resistor, a tenth inductor, a seventh resistor and an eighth resistor; the fourth end of the third common-mode inductor is connected to the third end of the first common-mode inductor; the second end of the third common-mode inductor is connected to the third end of the first common-mode inductor; one end of the ninth capacitor is grounded, and the other end is connected to the common end of the second end and the fourth end of the third common-mode inductor; the third end of the third common-mode inductor is connected to the third TUNER RF signal input end; the first end of the third common-mode inductor is connected to the fourth TUNER RF signal input end; the sixth resistor and the tenth inductor are connected in series, one end is connected to the third end of the third common-mode inductor, and the other end is connected to the first end of the common-mode inductor; one end of the seventh resistor is grounded, and the other end is connected to the third TUNER RF signal input end; one end of the eighth resistor is grounded, and the other end is connected to the fourth TUNER RF signal input end.

[0011] Furthermore, the model of the RF amplifier is BGU7045.

[0012] Beneficial effects of the utility model:

[0013] The utility model provides a signal amplification and filtering circuit supporting 4-way TUNER. The circuit utilizes the characteristics of the first-level common-mode anti-interference circuit, the first-level and second-level common-mode anti-interference circuit, and the second-level common-mode anti-interference circuit to decompose the signal amplified by one LAN signal amplification circuit into two signals, and then decompose the two signals into four signals through the first-level and second-level common-mode anti-interference circuits and the second-level common-mode anti-interference circuits. Moreover, the first-level and second-level common-mode anti-interference circuits and the second-level common-mode anti-interference circuits are used between each two signals. Only one LAN signal amplification circuit is needed for the 4-way TUNER radio frequency signal input terminals, which solves the problem of mutual interference when multiple TUNER radio frequency signal input terminals work at the same time; thereby improving the stability of the signal reception of the product. At the same time, the layout space of PCB components in the set-top box is reduced, so that the product can be made more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a module diagram of a signal amplification and filtering circuit supporting 4-channel TUNER in the utility model;

[0015] Figure 2 The utility model is a circuit schematic diagram of a signal amplification and filtering circuit supporting 4-channel TUNER. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0018] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0019] The utility model provides a signal amplifying and filtering circuit supporting 4-channel TUNER.

[0020] In the embodiment of the present utility model, Figure 1-2 As shown, a signal amplification and filtering circuit supporting 4-way TUNER is applied to a set-top box, including a radio frequency signal input pin, an FM filtering circuit, a WIFI filtering circuit, a LAN signal amplification circuit, a primary common-mode anti-interference circuit, a first secondary common-mode anti-interference circuit, a second secondary common-mode anti-interference circuit, a first TUNER radio frequency signal input terminal, a second TUNER radio frequency signal input terminal, a third TUNER radio frequency signal input terminal and a fourth TUNER radio frequency signal input terminal, the radio frequency signal input pin is used to transmit an external antenna signal to the FM filtering circuit, and the output terminal of the FM filtering circuit is connected to the input terminal of the WIFI filtering circuit. The input end of the WIFI filter circuit is electrically connected to the input end of the LAN signal amplifying circuit, the output end of the LAN signal amplifying circuit is electrically connected to the output end of the first common-mode anti-interference circuit, the output end of the first common-mode anti-interference circuit is electrically connected to the input ends of the first and second common-mode anti-interference circuits, respectively, the output ends of the first and second common-mode anti-interference circuits are electrically connected to the first TUNER RF signal input end and the second TUNER RF signal input end, respectively, the output ends of the second and second common-mode anti-interference circuits are electrically connected to the third TUNER RF signal input end and the fourth TUNER RF signal input end, respectively.

[0021] In this embodiment, the FM filter circuit includes a first inductor, a second inductor, a third inductor, a first capacitor, a second capacitor and a third capacitor; the first inductor, the second inductor and the third capacitor are connected in series, one end of which is connected to the RF signal input pin, and the other end is grounded; one end of the first capacitor is connected to the RF signal input pin, and the other end is connected to the common end of the first inductor and the second inductor; the second capacitor and the third inductor are connected in parallel, one end is connected to the common end of the first inductor and the second inductor, and the other end is connected to the WIFI filter circuit.

[0022] In this embodiment, the WIFI filter circuit includes a fourth inductor, a fifth inductor and a fourth capacitor; the fourth inductor, the fifth inductor and the fourth capacitor are connected in series, one end of which is connected to the common end of the second capacitor and the third inductor, and the other end is grounded.

[0023] In this embodiment, the LAN signal amplifying circuit includes a radio frequency amplifier, a sixth inductor, a seventh inductor, a fifth capacitor, a sixth capacitor, a first resistor and a power supply circuit; the second pin of the radio frequency amplifier is electrically connected to the power supply circuit; one end of the seventh inductor is electrically connected to the first pin of the radio frequency amplifier, and the other end is electrically connected to the power supply circuit; one end of the sixth inductor is connected to the common end of the fourth inductor and the fifth inductor, and the other end is connected to the sixth pin of the radio frequency amplifier; the fifth pin of the radio frequency amplifier is grounded; one end of the sixth capacitor is connected to the fourth pin of the radio frequency amplifier, and the other end is grounded; one end of the first resistor is connected to the fourth pin of the radio frequency amplifier, and the other end is connected to the GPIO interface.

[0024] In this embodiment, the first-level common-mode anti-interference circuit includes a first common-mode inductor, a seventh capacitor, an eighth inductor and a second resistor; the second end of the first common-mode inductor is connected to the fifth capacitor; one end of the seventh capacitor is grounded, and the other end is connected to the second end of the first common-mode inductor; the fourth end of the first common-mode inductor is connected to the fifth capacitor; the second resistor and the eighth inductor are connected in series, one end is connected to the third end of the first common-mode inductor, and the other end is connected to the first end of the first common-mode inductor.

[0025] In this embodiment, the first and second common-mode anti-interference circuit includes a second common-mode inductor, an eighth capacitor, a third resistor, a ninth inductor, a fourth resistor and a fifth resistor; the fourth end of the second common-mode inductor is connected to the third end of the first common-mode inductor; the second end of the second common-mode inductor is connected to the third end of the first common-mode inductor; one end of the eighth capacitor is grounded, and the other end is connected to the common end of the second end and the fourth end of the second common-mode inductor; the third end of the second common-mode inductor is connected to the first TUNER RF signal input end; the first end of the second common-mode inductor is connected to the second TUNER RF signal input end; the third resistor and the ninth inductor are connected in series, one end is connected to the third end of the second common-mode inductor, and the other end is connected to the first end of the common-mode inductor; one end of the fourth resistor is grounded, and the other end is connected to the first TUNER RF signal input end; one end of the fifth resistor is grounded, and the other end is connected to the second TUNER RF signal input end.

[0026] In this embodiment, the second secondary common-mode anti-interference circuit includes a third common-mode inductor, a ninth capacitor, a sixth resistor, a tenth inductor, a seventh resistor and an eighth resistor; the fourth end of the third common-mode inductor is connected to the third end of the first common-mode inductor; the second end of the third common-mode inductor is connected to the third end of the first common-mode inductor; one end of the ninth capacitor is grounded, and the other end is connected to the common end of the second end and the fourth end of the third common-mode inductor; the third end of the third common-mode inductor is connected to the third TUNER RF signal input end; the first end of the third common-mode inductor is connected to the fourth TUNER RF signal input end; the sixth resistor and the tenth inductor are connected in series, one end is connected to the third end of the third common-mode inductor, and the other end is connected to the first end of the common-mode inductor; one end of the seventh resistor is grounded, and the other end is connected to the third TUNER RF signal input end; one end of the eighth resistor is grounded, and the other end is connected to the fourth TUNER RF signal input end.

[0027] In this embodiment, the model of the RF amplifier is BGU7045.

[0028] It should be noted that in the present application, the model of the RF amplifier may also be other models.

[0029] Specifically, an antenna is externally connected to one end of the RF signal input pin, and the external antenna signal is input from the RF signal input pin RF_IN. The input external antenna signal passes through the FM filter circuit to filter out FM interference signals; and passes through the WiFi filter circuit again to filter out WiFi interference signals; after the external antenna signal input from the front end passes through the FM filter circuit and the WiFi filter circuit to filter out useless signals, what remains is the useful signal required by the set-top box TUNER, and the useful signal enters the LNA signal amplifier circuit for amplification. The signal amplified by the LNA signal amplifier circuit is coupled to the first-level common-mode anti-interference circuit through the fifth capacitor 10C65, and after passing through the first-level common-mode anti-interference circuit, two TUNER RF signals are separated, namely signal A and signal B; similarly, signals A and B respectively enter the first and second common-mode anti-interference circuits and the second and second common-mode anti-interference circuits and separate 4 RF signals C, D, E, and F, and the 4 RF signals enter the 4 TUNERs respectively. This circuit makes full use of the characteristics of common-mode inductors to decompose the signal amplified by one LNA signal amplifier circuit into two signals, and the two signals into four signals. In addition, the interference between each two signals can be offset by the second common-mode inductor, the third common-mode inductor and their peripheral circuits.

[0030] This circuit solves the mutual interference problem when a single-channel signal amplifier supports multiple-channel TUNERs working simultaneously.

[0031] In the existing common 4-channel TUNER set-top box products, there are usually 4 LNA low-noise signal amplification circuits (that is, each TUNER corresponds to one RF amplifier to avoid mutual interference between the 4 TUNERs working at the same time). In this circuit, the 4 TUNERs only need one RF amplifier to solve the mutual interference problem between the 4 TUNERs working at the same time; thus improving the stability of the signal reception of the set-top box, while also reducing the PCB component layout space in the set-top box, which can make the product more compact.

[0032] The above description is only a preferred embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the utility model concept, or directly / indirectly used in other related technical fields are included in the patent protection scope of the utility model.

Claims

1. A signal amplifying and filtering circuit supporting 4-channel TUNER, the signal amplifying and filtering circuit is applied to a set-top box, characterized in that: The invention comprises a radio frequency signal input pin, an FM filter circuit, a WIFI filter circuit, a LAN signal amplifying circuit, a primary common mode anti-interference circuit, a first secondary common mode anti-interference circuit, a second secondary common mode anti-interference circuit, a first TUNER radio frequency signal input terminal, a second TUNER radio frequency signal input terminal, a third TUNER radio frequency signal input terminal and a fourth TUNER radio frequency signal input terminal, wherein the radio frequency signal input pin is used to transmit an external antenna signal to the FM filter circuit, the output terminal of the FM filter circuit is electrically connected to the input terminal of the WIFI filter circuit, and the output terminal of the WIFI filter circuit is electrically connected to the input terminal of the WIFI filter circuit. The input end of the LAN signal amplifying circuit is electrically connected, the output end of the LAN signal amplifying circuit is electrically connected to the output end of the first-level common-mode anti-interference circuit, the output end of the first-level common-mode anti-interference circuit is electrically connected to the input ends of the first-level common-mode anti-interference circuit and the second-level common-mode anti-interference circuit respectively, the output end of the first-level common-mode anti-interference circuit is electrically connected to the first TUNER RF signal input end and the second TUNER RF signal input end respectively, and the output end of the second-level common-mode anti-interference circuit is electrically connected to the third TUNER RF signal input end and the fourth TUNER RF signal input end respectively.

2. The signal amplification and filtering circuit supporting 4-channel TUNER as claimed in claim 1, characterized in that: The FM filter circuit includes a first inductor, a second inductor, a third inductor, a first capacitor, a second capacitor and a third capacitor; the first inductor, the second inductor and the third capacitor are connected in series, one end of which is connected to the RF signal input pin, and the other end is grounded; one end of the first capacitor is connected to the RF signal input pin, and the other end is connected to the common end of the first inductor and the second inductor; the second capacitor and the third inductor are connected in parallel, one end of which is connected to the common end of the first inductor and the second inductor, and the other end is connected to the WIFI filter circuit.

3. The signal amplification and filtering circuit supporting 4-channel TUNER as claimed in claim 2, characterized in that: The WIFI filter circuit includes a fourth inductor, a fifth inductor and a fourth capacitor; the fourth inductor, the fifth inductor and the fourth capacitor are connected in series, one end of which is connected to the common end of the second capacitor and the third inductor, and the other end is grounded.

4. The signal amplifying and filtering circuit supporting 4-channel TUNER as claimed in claim 3, characterized in that: The LAN signal amplification circuit includes a radio frequency amplifier, a sixth inductor, a seventh inductor, a fifth capacitor, a sixth capacitor, a first resistor and a power supply circuit; the second pin of the radio frequency amplifier is electrically connected to the power supply circuit; one end of the seventh inductor is electrically connected to the first pin of the radio frequency amplifier, and the other end is electrically connected to the power supply circuit; one end of the sixth inductor is connected to the common end of the fourth inductor and the fifth inductor, and the other end is connected to the sixth pin of the radio frequency amplifier; the fifth pin of the radio frequency amplifier is grounded; one end of the sixth capacitor is connected to the fourth pin of the radio frequency amplifier, and the other end is grounded; one end of the first resistor is connected to the fourth pin of the radio frequency amplifier, and the other end is connected to the GPIO interface.

5. The signal amplifying and filtering circuit supporting 4-channel TUNER as claimed in claim 4, characterized in that: The first-level common-mode anti-interference circuit includes a first common-mode inductor, a seventh capacitor, an eighth inductor and a second resistor; the second end of the first common-mode inductor is connected to the fifth capacitor; one end of the seventh capacitor is grounded, and the other end is connected to the second end of the first common-mode inductor; the fourth end of the first common-mode inductor is connected to the fifth capacitor; the second resistor and the eighth inductor are connected in series, one end is connected to the third end of the first common-mode inductor, and the other end is connected to the first end of the first common-mode inductor.

6. The signal amplifying and filtering circuit supporting 4-channel TUNER as claimed in claim 5, characterized in that: The first and second level common mode anti-interference circuit includes a second common mode inductor, an eighth capacitor, a third resistor, a ninth inductor, a fourth resistor and a fifth resistor; the fourth end of the second common mode inductor is connected to the third end of the first common mode inductor; the second end of the second common mode inductor is connected to the third end of the first common mode inductor; one end of the eighth capacitor is grounded, and the other end is connected to the common end of the second end and the fourth end of the second common mode inductor; the third end of the second common mode inductor is connected to the first TUNER RF signal input end; the first end of the second common mode inductor is connected to the second TUNER RF signal input end; the third resistor and the ninth inductor are connected in series, one end is connected to the third end of the second common mode inductor, and the other end is connected to the first end of the common mode inductor; one end of the fourth resistor is grounded, and the other end is connected to the first TUNER RF signal input end; one end of the fifth resistor is grounded, and the other end is connected to the second TUNER RF signal input end.

7. The signal amplifying and filtering circuit supporting 4-channel TUNER as claimed in claim 6, characterized in that: The second secondary common-mode anti-interference circuit includes a third common-mode inductor, a ninth capacitor, a sixth resistor, a tenth inductor, a seventh resistor and an eighth resistor; the fourth end of the third common-mode inductor is connected to the third end of the first common-mode inductor; the second end of the third common-mode inductor is connected to the third end of the first common-mode inductor; one end of the ninth capacitor is grounded, and the other end is connected to the common end of the second end and the fourth end of the third common-mode inductor; the third end of the third common-mode inductor is connected to the third TUNER RF signal input end; the first end of the third common-mode inductor is connected to the fourth TUNER RF signal input end; the sixth resistor and the tenth inductor are connected in series, one end is connected to the third end of the third common-mode inductor, and the other end is connected to the first end of the common-mode inductor; one end of the seventh resistor is grounded, and the other end is connected to the third TUNER RF signal input end; one end of the eighth resistor is grounded, and the other end is connected to the fourth TUNER RF signal input end.

8. The signal amplifying and filtering circuit supporting 4-channel TUNER as claimed in claim 4, characterized in that: The model of the radio frequency amplifier is BGU7045.

Images