CN108632654B - Signal switching circuit and front-end circuit - Google Patents
Signal switching circuit and front-end circuit Download PDFInfo
- Publication number
- CN108632654B CN108632654B CN201710177629.7A CN201710177629A CN108632654B CN 108632654 B CN108632654 B CN 108632654B CN 201710177629 A CN201710177629 A CN 201710177629A CN 108632654 B CN108632654 B CN 108632654B
- Authority
- CN
- China
- Prior art keywords
- electrically connected
- capacitor
- circuit
- resistor
- inductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- H04N21/426—Internal components of the client ; Characteristics thereof
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/222—Studio circuitry; Studio devices; Studio equipment
- H04N5/262—Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
- H04N5/268—Signal distribution or switching
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Electronic Switches (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
A signal switching circuit for switching a radio frequency signal to different channels, the signal switching circuit comprising: the first capacitor, the first inductor, the first branch circuit and the second branch circuit. The first end of the first capacitor is used as an input end. The first end of the first inductor is electrically connected with the first end of the first capacitor, and the second end of the first inductor is electrically connected with the ground terminal. The first branch circuit is electrically connected with the second end of the first capacitor and is used for conducting the input end and the first output end. The second branch circuit is electrically connected with the second end of the first capacitor and used for conducting the input end and the second output end. The invention also discloses a front-end circuit. The signal switching circuit and the front-end circuit provided by the invention replace a special separator by a circuit consisting of a resistor, an inductor and a capacitor so as to realize the separation and output of input signals, thereby saving the development cost.
Description
Technical Field
The present invention relates to signal processing circuits, and more particularly, to a signal switching circuit and a front-end circuit.
Background
In a front-end circuit of a Set-Top Box (Set Top Box), a switching circuit switching signal needs to be constructed, so that signals in the front-end circuit can be switched to different circuits for transmission in different time periods. At present, a switching device special for switching signals is needed, however, the unit price of the controller is higher, so that the development cost of the set-top box is higher.
Disclosure of Invention
Accordingly, there is a need for a signal switching circuit and a front-end circuit to reduce the development cost.
A signal switching circuit provided in an embodiment of the present invention is configured to switch a radio frequency signal to different channels, and the signal switching circuit includes: the first capacitor, the first inductor, the first branch circuit and the second branch circuit.
The first end of the first capacitor is used as an input end. The first end of the first inductor is electrically connected with the first end of the first capacitor, and the second end of the first inductor is electrically connected with the ground terminal. The first branch circuit is electrically connected with the second end of the first capacitor and is used for conducting the input end and the first output end. The second branch circuit is electrically connected with the second end of the first capacitor and used for conducting the input end and the second output end.
Preferably, the first branch comprises: the circuit comprises a first resistor, a second resistor, an N-channel JFET (Junction Field Effect Transistor), a second inductor and a direct current power supply. The grid electrode of the N-channel JFET is electrically connected with the first end of the first resistor, the drain electrode of the N-channel JFET is electrically connected with the second end of the first capacitor and the first end of the second resistor, and the source electrode of the N-channel JFET serves as a first output end. The first end of the second inductor is electrically connected with the second end of the second resistor. The positive pole of the direct current power supply is electrically connected with the second end of the first resistor and the second end of the second inductor, and the negative pole of the direct current power supply is electrically connected with the grounding end.
Preferably, when the dc power supply is powered off and does not supply power, the drain is conducted with the source, the input end is conducted with the first output end, and the radio frequency signal is output from the first branch; when the direct current power supply is electrified and supplies power, the drain electrode and the source electrode are not conducted, and the radio frequency signal is output from the second branch circuit.
Preferably, the second branch comprises: the diode, the second capacitor, the third resistor, the third inductor and the fourth inductor. The anode of the diode is electrically connected with the second end of the first capacitor. The first end of the second capacitor is electrically connected with the cathode of the diode, and the second end of the second capacitor is used as a second output end. The first end of the third resistor is electrically connected with the cathode of the diode. The third inductor is electrically connected between the second end of the third resistor and ground. The fourth inductor is electrically connected between the second end of the second capacitor and ground.
The present invention also provides a front-end circuit, including: a duplexer, a low noise amplifier, a first System-on-a-Chip (SOC), a second System-on-a-Chip (SOC), and the signal switching circuit. The low noise amplifier is electrically connected with the duplexer, the first system on chip is used for processing high-definition digital signals, and the second system on chip is electrically connected with the first system on chip and is used for modulating, demodulating and mixing radio-frequency signals
The signal switching circuit and the front-end circuit realize the separation and output of the input signals by replacing a special separator through a circuit consisting of the resistor, the inductor and the capacitor, thereby saving the development cost.
Drawings
Fig. 1 is an architecture diagram of a front-end circuit according to an embodiment of the present invention.
Fig. 2 is a circuit diagram of a signal switching circuit according to an embodiment of the invention.
Fig. 3 is a scattering parameter measurement diagram of an embodiment of the signal switching circuit of the present invention.
Fig. 4 is a scattering parameter measurement diagram of an embodiment of the signal switching circuit of the present invention.
Fig. 5 is an isolation measurement diagram of a signal switching circuit according to an embodiment of the invention.
Description of the main elements
Change-over switch S
First system on a sheet S1
Second System-on-chip S2
Signal access terminal IN
Input terminal IN1
Duplexer Dip
Low noise amplifier LNA
Signal switching circuit SW
Output terminal OUT
First output terminal OUT1
Second output terminal OUT2
DC power supply V
First branch B1
Second branch B2
First capacitor C1
Second capacitance C2
First inductance L1
Second inductance L2
Third inductance L3
Fourth inductance L4
First resistor R1
Second resistor R2
Third resistor R3
Diode D
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
Referring to fig. 1, fig. 1 is a schematic diagram of a front-end circuit according to a first embodiment of the present invention. In the present embodiment, the front-end circuit is used for signal processing, and includes a duplexer Dip, a low noise amplifier LNA, a System-on-a-Chip (SOC) S1, a System-on-Chip (SOC) S2, and a signal switching circuit SW.
The duplexer Dip isolates the transmitting signal from the receiving signal, and ensures that both the receiving channel and the transmitting channel can work normally at the same time, so that when the receiving signal is input to the front-end circuit from the signal access terminal IN, the transmitting signal of the duplexer Dip is not interfered. The low noise amplifier LNA is used for amplifying the received weak radio frequency signal and reducing the interference of the noise of the amplifier to the radio frequency signal as much as possible so as to improve the signal to noise ratio of the output signal. The first system on chip S1 integrates a full-band capture technology and a video service technology, can process high-definition digital signals, and can be mainly applied to data processing of a high-definition digital cable set-top box. The first system on chip S2 is a chip conforming to the DOCSIS (Data Over Cable Interface Specifications) 2.0 standard, and is mainly used for processing radio frequency signals such as modulation, demodulation, and frequency mixing, and the bandwidth can reach 1 hertz (GHz). In this embodiment, a chip of model number BCM7584 may be used as the first system on chip S1, and a chip of model number BCM3308 may be used as the first system on chip S2. The signal switching circuit SW is mainly used for switching the rf signal to different signal processing paths.
The rf signal is input to the front-end circuit from the signal input terminal IN, and by switching of the signal switching circuit SW, the rf signal can reach the output terminal OUT through the first path formed by the duplexer Dip, the low noise amplifier LNA and the signal switching circuit SW which are electrically connected IN sequence, or the rf signal can reach the output terminal OUT through the second path formed by the duplexer Dip, the low noise amplifier LNA, the signal switching circuit SW and the first system on a chip S1 which are electrically connected IN sequence. And in the process of transmitting the radio frequency signal in the second path, the first system on chip S1 and the first system on chip S2 perform data communication and data processing on the radio frequency signal, and then transmit the signal to the output terminal OUT through the first system on chip S1 to output the processed signal. Or after the first system on chip S1 and the first system on chip S2 perform data communication and data processing on the rf signals, the signals are uploaded to the signal input terminal IN through the first system on chip S2 and the duplexer Dip, so as to transmit the processed signals.
Referring to fig. 2, fig. 2 is a circuit diagram of a signal switching circuit SW according to an embodiment of the present invention.
In this embodiment, the signal switching circuit SW includes a first inductor L1, a first capacitor C1, a first branch B1 and a second branch B2.
A first terminal of the first capacitor C1, serving as an input terminal IN1, is electrically connected to the first branch B1 and the second branch B2 through the first capacitor C1. The input terminal IN1 is electrically connected to the LNA, and the input terminal IN1 is connected to the ground through the first inductor L1, where the ground described herein may refer to the ground of a specific circuit or product, and may also refer to the common ground, which is not limited herein.
The first branch B1 includes a switch S, a first resistor R1, a second resistor R2, a second inductor L2, and a dc power source V. In the present embodiment, the switch S is an N-channel JFET (Junction Field Effect Transistor). In other embodiments, the switch S may also use other switching elements to perform the switching function, such as other types of fets as the switch. In this embodiment, the gate of the switch S (i.e., the N-channel JFET) is electrically connected to the first terminal of the first resistor R1, the drain of the N-channel JFET is electrically connected to the second terminal of the first capacitor C1 and the first terminal of the second resistor R2, and the source of the N-channel JFET is used as the first output terminal OUT1 of the signal switching circuit SW. The second terminal of the second resistor R2 is electrically connected to the first terminal of the second inductor L2, and the second terminal of the first resistor R1 and the second terminal of the second inductor L2 are both electrically connected to the positive terminal of the dc power source V. The negative pole of the dc power supply V is grounded.
The second branch B2 includes a diode D, a second capacitor C2, a third resistor R3, a third inductor L3, and a fourth inductor L4. The anode of the diode D is electrically connected to the second terminal of the first capacitor C1, and the cathode of the diode D is electrically connected to the first terminal of the second capacitor C2 and the first terminal of the third resistor R3. A second terminal of the third resistor R3 is connected to ground through a third inductor L3. The second terminal of the second capacitor C2 serves as the second output terminal OUT2 of the signal switching circuit SW, and the second terminal of the second capacitor C2 is grounded through the fourth inductor L4.
In this embodiment, the rf signal enters the signal switching circuit SW, and is filtered and the like before outputting the processed signal. The switching action of the signal switching circuit SW is directly controlled by the direct current power supply V, so that the corresponding conduction of the first branch and the second branch can be controlled by the change-over switch, and the radio frequency signals can be output from different branches. When the dc power supply V is powered off and is not supplying power, the gate of the N-channel JFET is at a low level, the drain of the N-channel JFET is conducted with the source of the N-channel JFET, the first output terminal OUT1 of the signal switching circuit SW is conducted with the input terminal IN1, and the rf signal is directly transmitted from the input terminal IN1 to the first output terminal OUT 1. When the dc power source V is powered on, the gate of the N-channel JFET is at a high level, the drain of the N-channel JFET is not conducted with the source of the N-channel JFET, and the rf signal is output from the second branch B2, i.e., transmitted to the second output terminal OUT2 through the diode D and the second capacitor C2.
In the first embodiment of the front-end circuit, the first output terminal OUT1 of the signal switching circuit SW is directly electrically connected to the output terminal OUT of the front-end circuit, and the second output terminal OUT2 of the signal switching circuit SW is electrically connected to the first system-on-chip S1. When the direct current power supply V is powered off and does not supply power, the radio frequency signal reaches the output end OUT of the front-end circuit through a first path formed by a duplexer Dip, a low noise amplifier LNA and a signal switching circuit SW which are electrically connected in sequence. When the dc power source V is powered on, the rf signal is transmitted to the first system on chip S1 and the first system on chip S2 through the second path for data communication and data processing.
Fig. 3 is a scattering parameter measurement diagram of the signal switching circuit SW according to an embodiment of the present invention.
Fig. 4 is a scattering parameter measurement diagram of the signal switching circuit SW according to an embodiment of the present invention.
Fig. 5 is an isolation measurement diagram of the signal switching circuit SW according to an embodiment of the invention.
IN the embodiment of fig. 3, the dc power supply V is powered off, the gate of the N-channel JFET is low, the drain of the N-channel JFET is turned on, the source of the N-channel JFET is turned on, and the first output terminal OUT1 of the signal switching circuit SW is turned on with the input terminal IN 1. At this time, the scattering parameters of the input terminal IN1 of the signal switching circuit SW and the first output terminal OUT1 of the signal switching circuit SW are as shown IN fig. 3. It can be seen that the scattering parameters S11 and S22 are both less than-10 dB and the scattering parameters S12 and S21 are also close to 0dB at most frequency points below 1 GHz.
IN the embodiment of fig. 4, the dc power source V is powered on, the gate of the N-channel JFET is high, the drain of the N-channel JFET is not conductive with the source of the N-channel JFET, and the rf signal is transmitted from the input terminal IN1 of the signal switching circuit SW to the second output terminal OUT 2. At this time, the scattering parameters of the input terminal IN1 of the signal switching circuit SW and the second output terminal OUT2 of the signal switching circuit SW are as shown IN fig. 4. It can be seen that the scattering parameters S11 and S22 are both less than-10 dB and the scattering parameters S12 and S21 are also close to 0dB at most frequency points below 1 GHz. The performance meets the relevant requirements.
In the embodiment of fig. 5, the isolation between the two output terminals of the signal switching circuit SW is less than-18 dB, and the isolation is very low, which meets the requirement.
The signal switching circuit SW and the front-end circuit provided by the invention have better performance, and the signal switching circuit SW formed by the N-channel JFET and the resistor, the inductor and the capacitor replaces a switching device specially used for switching signals, so that the switching output of input signals is realized, and the development cost is saved.
It is understood that various other changes and modifications may be made by those skilled in the art based on the technical idea of the present invention, and all such changes and modifications should fall within the protective scope of the claims of the present invention.
Claims (3)
1. A signal switching circuit for switching a radio frequency signal to different channels, the signal switching circuit comprising:
a first capacitor, a first end of which is used as an input end;
a first end of the first inductor is electrically connected with the first end of the first capacitor, and a second end of the first inductor is electrically connected with a ground end;
the first branch circuit is electrically connected with the second end of the first capacitor; and
the second branch circuit is electrically connected with the second end of the first capacitor;
wherein the first branch further comprises:
a first resistor;
a second resistor;
the first end of the second inductor is electrically connected with one end of the second resistor; and
the positive electrode of the direct current power supply is electrically connected with the second end of the first resistor and the second end of the second inductor, and the negative electrode of the direct current power supply is electrically connected with the ground terminal; and
a switch for controlling the conduction of the first branch and the second branch to output the radio frequency signal from different branches, wherein the switch is an N-channel JFET (Junction Field Effect Transistor), a gate of the switch is electrically connected to a first end of the first resistor, a drain of the switch is electrically connected to a second end of the first capacitor and another end of the second resistor, and a source of the switch is used as a first output end;
when the direct current power supply is powered off and does not supply power, the drain electrode is conducted with the source electrode, the input end is conducted with the first output end, and the radio-frequency signal is output from the first branch circuit; when the direct current power supply is powered on, the drain electrode is not conducted with the source electrode, and the radio frequency signal is output from the second branch circuit.
2. The signal switching circuit of claim 1, wherein the second branch comprises:
a diode, the anode of which is electrically connected with the second end of the first capacitor;
a second capacitor, wherein the first end of the second capacitor is electrically connected with the cathode of the diode, and the second end of the second capacitor is used as a second output end;
a third resistor, a first end of which is electrically connected with the cathode of the diode;
a third inductor electrically connected between a second end of the third resistor and ground; and
a fourth inductor electrically connected between the second end of the second capacitor and ground.
3. A front-end circuit, comprising:
a duplexer;
the low-noise amplifier is electrically connected with the duplexer;
a first System-on-a-Chip (SOC) for processing high-definition digital signals;
a second System-on-a-Chip (SOC) electrically connected to the first SOC, for modulating, demodulating and mixing the rf signal; and
the signal switching circuit of any one of claims 1 and 2, configured to switch the radio frequency signal to different channels.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710177629.7A CN108632654B (en) | 2017-03-23 | 2017-03-23 | Signal switching circuit and front-end circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710177629.7A CN108632654B (en) | 2017-03-23 | 2017-03-23 | Signal switching circuit and front-end circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108632654A CN108632654A (en) | 2018-10-09 |
| CN108632654B true CN108632654B (en) | 2021-10-22 |
Family
ID=63706409
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710177629.7A Active CN108632654B (en) | 2017-03-23 | 2017-03-23 | Signal switching circuit and front-end circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108632654B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1294617A (en) * | 1971-05-10 | 1972-11-01 | Matsushita Electronics Corp | Synchronising signal separating circuit |
| US5347245A (en) * | 1993-11-05 | 1994-09-13 | Bark Lee Yee | CATV signal splitter |
| CN1806435A (en) * | 2003-10-31 | 2006-07-19 | 三洋电机株式会社 | Analog/digital-compatible front-end module |
| CN101141551A (en) * | 2006-09-08 | 2008-03-12 | 深圳市同洲电子股份有限公司 | Digital bidirectional set up box |
| CN105472275A (en) * | 2014-09-09 | 2016-04-06 | 国基电子（上海）有限公司 | Signal separation circuit and front-end circuit |
-
2017
- 2017-03-23 CN CN201710177629.7A patent/CN108632654B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1294617A (en) * | 1971-05-10 | 1972-11-01 | Matsushita Electronics Corp | Synchronising signal separating circuit |
| US5347245A (en) * | 1993-11-05 | 1994-09-13 | Bark Lee Yee | CATV signal splitter |
| CN1806435A (en) * | 2003-10-31 | 2006-07-19 | 三洋电机株式会社 | Analog/digital-compatible front-end module |
| CN101141551A (en) * | 2006-09-08 | 2008-03-12 | 深圳市同洲电子股份有限公司 | Digital bidirectional set up box |
| CN105472275A (en) * | 2014-09-09 | 2016-04-06 | 国基电子（上海）有限公司 | Signal separation circuit and front-end circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108632654A (en) | 2018-10-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104969479B (en) | The RF front-end modules of LNA bypass mode insertion loss are reduced using single-pole three-throw switch | |
| CN108063627B (en) | Radio frequency receiving and transmitting switch | |
| US8253485B2 (en) | Power amplifier | |
| US9031517B2 (en) | Transmit-receive front end | |
| EP2847869B1 (en) | A transceiver with an integrated rx/tx configurable passive network | |
| US10153803B2 (en) | Receiving circuit, wireless communication module, and wireless communication device | |
| CN214626968U (en) | Radio frequency device | |
| CN113992234B (en) | Circuit for vehicle V2X device, vehicle V2X device and vehicle | |
| CN103973280A (en) | High frequency semiconductor switch and wireless device | |
| CN111865283B (en) | High power radio frequency switch with low leakage current and low insertion loss | |
| KR20120098543A (en) | High-frequency switching assembly, transmitter and method | |
| CN106470026A (en) | A kind of radio-frequency switch circuit and radio frequency link | |
| US9413415B2 (en) | High frequency module | |
| CN104935317A (en) | CMOS SOI radio frequency switch structure capable of realizing low insertion loss and low harmonic | |
| US8948714B2 (en) | Low noise converter of satellite broadcasting receiver | |
| CN108306623A (en) | Low-noise amplifier | |
| CN108632654B (en) | Signal switching circuit and front-end circuit | |
| CN103138684B (en) | Amplifying circuit and the radio communication device comprising this amplifying circuit | |
| CN103595385A (en) | Radio frequency switch circuit of III-V group MOSFET device | |
| CN115102566B (en) | Wireless communication system and signal transceiver thereof | |
| CN202268461U (en) | Multi-frequency combiner and intelligent signal gating circuit thereof | |
| CN212694057U (en) | Positioning circuit and positioning device | |
| CN112649816A (en) | Positioning circuit and positioning device | |
| CN203057075U (en) | Low-noise amplifier | |
| KR101481031B1 (en) | Device of Tuner for isolating Input and Switching System for comprising thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |