A system for resolving ENDC combinational coexistence interference using Chebyshev circuits

Abstract

This invention discloses a system for resolving ENDC combination coexistence interference using a Chebyshev circuit, comprising: an LTE system for outputting signals; a power amplifier for amplifying signals and connected to the LTE system; a Chebyshev circuit for suppressing second harmonic signal strength and connected to the power amplifier; a duplexer for isolating transmitted and received signals to ensure simultaneous normal operation of both transmission and reception, connected to the Chebyshev circuit; a switch for controlling on / off operation and connected to the duplexer; a tripplexer for isolating transmitted and received signals to ensure simultaneous normal operation of both transmission and reception, connected to the switch; an antenna interface for connecting an antenna and connected to the tripplexer; and a receiving module for receiving signals and connected to the tripplexer. The beneficial effect of this invention is that it can suppress second harmonics through a custom Chebyshev circuit, solving the problem of second harmonic interference on the sensitivity of the receiving module.

Description

Technical Field

[0001] This invention relates to the field of harmonic suppression technology, and in particular to a system for solving ENDC combined coexistence interference using Chebyshev circuits. Background Technology

[0002] Currently, the 5G radio frequency (RF) front-end is the most important part of realizing 5G communication. The RF front-end mainly consists of power amplifiers, RF transceivers, antenna switches, duplexers, and RF filters. With the continuous increase in 5G frequency bands, the market demand for 5G RF filters is also growing.

[0003] In existing technologies, low-pass filters are used to suppress the second harmonic of LTE B3. However, low-pass filters have large package sizes and high prices, which are not conducive to layout and will increase the cost of devices. They also have the problem of not being able to flexibly suppress the interference of the second harmonic on the receiving module. Summary of the Invention

[0004] To address the shortcomings of existing technologies in flexibly suppressing the interference of second harmonics on the receiving module, this invention proposes a system that utilizes a Chebyshev circuit to solve the interference of ENDC combination coexistence. This system can suppress second harmonics through a custom Chebyshev circuit, thus solving the problem of second harmonic interference on the sensitivity of the receiving module.

[0005] The following is the technical solution of the present invention: a system for solving ENDC combinational coexistence interference using Chebyshev circuits, comprising:

[0006] LTE system, used for outputting signals;

[0007] Power amplifier, used to amplify signals and connect to LTE systems;

[0008] Chebyshev circuits are used to suppress the intensity of second harmonic signals and are connected to power amplifiers.

[0009] A duplexer is used to isolate transmitted and received signals, ensuring that both transmission and reception can work normally at the same time. It is connected to a Chebyshev circuit.

[0010] A switch is used to control opening and closing, and connects to a duplexer;

[0011] A tripod is used to isolate the transmitted and received signals, ensuring that both transmission and reception can work normally at the same time, and it connects to a switch;

[0012] Antenna interface, used to connect the antenna and the tripod;

[0013] The receiving module is used to receive signals and connect to the tripod.

[0014] In this solution, the signal output by the LTE system is amplified by the power amplifier, and the second harmonic is also amplified by the power amplifier. After passing through the duplexer, the second harmonic passes through the switch and then to the tripeller. Since the LTE system and the receiving module work simultaneously, the receiving module's reception also passes through the tripeller. The antenna interface is connected to the antenna. At this time, the second harmonic signal of the LTE system will interfere with the receiving module's reception, thereby affecting the receiving module's reception performance. A Chebyshev circuit is set between the power amplifier and the duplexer. The Chebyshev circuit suppresses the second harmonic of the LTE system at the output of the power amplifier, thus solving the problem of interference of the second harmonic of the LTE system on the receiving module's receiving sensitivity.

[0015] Preferably, the Chebyshev circuit has one or more components, and the multiple Chebyshev circuits are connected in series or in parallel.

[0016] In this scheme, there can be one or more Chebyshev circuits. Multiple Chebyshev circuits can be connected in series, in parallel, or in a combination of series and parallel. The purpose is to better solve the problem of interference of the second harmonic of the LTE system on the receiving sensitivity of the receiving module.

[0017] Preferably, the Chebyshev circuit consists of an LC low-pass filter circuit, a resonant circuit, and an inductor, with the resonant circuit connected in parallel to the LC low-pass filter circuit and the inductor connected in series with the LC low-pass filter circuit.

[0018] In this scheme, the Chebyshev circuit consists of an LC low-pass filter circuit, a resonant circuit, and an inductor. When only the LC low-pass filter circuit is used, the harmonic suppression is insufficient and the insertion loss is relatively large. By adding a resonant circuit to the LC low-pass filter circuit, the harmonics are improved and suppressed to above 25dB. However, the passband does not converge and the insertion loss is still relatively large. By adding an inductor to the resonant circuit, the interference intensity is reduced to 30dB. The Chebyshev circuit can replace the dedicated filter, reducing costs, and at the same time, it can solve the problem of second harmonic interference on the receiving module's receiving sensitivity.

[0019] Preferably, there are one or more resonant circuits, with only one series inductor. The resonant circuit is composed of an inductor and a capacitor connected in series, and the inductor of the resonant circuit is connected in parallel with the inductor of the LC low-pass filter circuit.

[0020] In this scheme, there can be one or more resonant circuits. The inductors of multiple resonant circuits are connected in parallel with the inductors of the LC low-pass filter circuit. The purpose is to better solve the problem of interference from the second harmonic of the LTE system on the receiving module's receiving sensitivity. There is only one series inductor, which further improves the interference strength.

[0021] Preferably, the applicable frequency band range is adjusted based on the number of Chebyshev circuits, the number of resonant circuits, or the component values ​​of the Chebyshev circuits, with the applicable frequency band range being 1.4 GHz to 10 GHz.

[0022] In this scheme, the applicable frequency band range can be changed by adjusting the number of Chebyshev circuits, the number of resonant circuits, or the component values ​​of the Chebyshev circuits. Without changing the connection method and components, the applicable frequency band can be changed by adjusting the number, or the applicable frequency band can be changed by directly adjusting the component values. The applicable frequency band range is from 1.4GHz to 10GHz.

[0023] Preferably, the receiving module is one or more of a SAW filter, an LTCC filter, and an IPD filter.

[0024] The beneficial effects of this invention are: by adding a Chebyshev circuit after the power amplifier output, the problem of excessive harmonic signal strength in a certain frequency band interfering with other frequency bands and causing performance degradation in the interfered frequency band can be solved; the Chebyshev circuit can replace a dedicated filter, reducing costs; the component values ​​of the Chebyshev circuit are adjustable, not limited to a certain frequency band, and have a wide range of applications, with an applicable frequency range from 1.4GHz to 10GHz; in addition to adjusting the component values, several Chebyshev circuits can also be used in series or parallel to adjust the suppression effect of secondary filtering. Attached Figure Description

[0025] Figure 1 This invention presents a schematic diagram of a system for resolving ENDC combinational coexistence interference using Chebyshev circuits.

[0026] Figure 2 This invention provides a Chebyshev circuit diagram for a system that utilizes a Chebyshev circuit to resolve ENDC combinational coexistence interference.

[0027] Figure 3 The present invention provides a Smith chart of a system that utilizes Chebyshev circuits to resolve ENDC combinational coexistence interference.

[0028] Figure 4 The present invention provides a first suppression variation diagram of a system for resolving ENDC combinational coexistence interference using Chebyshev circuits.

[0029] Figure 5 The present invention provides a second suppression variation diagram for a system that utilizes Chebyshev circuits to resolve ENDC combinational coexistence interference.

[0030] In the diagram: 1. LTE system; 2. Power amplifier; 3. Chebyshev circuit; 4. Duplexer; 5. Switch; 6. Triplexer; 7. Antenna interface; 8. Receiver module. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0032] Example: Figure 1 As shown, a system for resolving ENDC combinational coexistence interference using Chebyshev circuits includes:

[0033] LTE system 1, used for outputting signals;

[0034] Power amplifier 2, used to amplify the signal, is connected to LTE system 1;

[0035] Chebyshev circuit 3 is used to suppress the intensity of the second harmonic signal and is connected to power amplifier 2;

[0036] The duplexer 4 is used to isolate the transmitted and received signals, ensuring that both the receiving and transmitting signals can work normally at the same time, and is connected to the Chebyshev circuit 3;

[0037] Switch 5 is used to control opening and closing, and is connected to duplexer 4;

[0038] The tripod 6 is used to isolate the transmitted and received signals, ensuring that both the receiving and transmitting signals can work normally at the same time, and is connected to switch 5;

[0039] Antenna interface 7 is used to connect the antenna and connect the tripod 6;

[0040] Receiver module 8 is used to receive signals and is connected to tripod 6.

[0041] The LTE system 1 is LTE B3. The receiver module 8 can be a surface acoustic wave (SAW) filter or an n77 / 78 filter. The n77 / 78 filter can be an LTCC (Low Temperature Co-fired Ceramic) filter or an IPD (Integrated Passive Devices) filter.

[0042] There can be one or more Chebyshev circuits 3. Multiple Chebyshev circuits 3 can be connected in series, in parallel, or in a combination of series and parallel. The purpose is to better solve the problem of interference of the second harmonic of LTE system 1 on the receiving sensitivity of receiving module 8.

[0043] After the signal output from LTE B3 is amplified by power amplifier 2, the second harmonic is also amplified by power amplifier 2. The second harmonic then passes through duplexer 4, then switch 5, and finally triplexer 6. Since LTE B3 and n77 / 78 operate simultaneously in the ENDC (EUTRA NRDual-Connectivity) combination DC_3A_n77A or DC_3A_n78A, the reception of n77 / 78 also passes through triplexer 6, and the antenna is connected to the antenna via antenna interface 7. At this time, the second harmonic signal of LTE B3 will interfere with the reception of n77 / 78, thus affecting the reception performance of n77 / 78. The 3rd Generation Partnership Project (3GPP) protocol requires the single-channel reception sensitivity of n77 / 78 to be less than -80.8 dBm. The second harmonic signal strength of LTE B3 is -73 dBm, causing 7 dB interference to n77 / 78. The interference intensity to n77 / 78 is shown in Table 1.

[0044] Table 1 shows the intensity of interference to n77 / 78 without using Chebyshev circuit 3.

[0045] Interference intensity of n77 / 78 Power Amplifier 2 Output -12dbm Duplexer 4 suppression 40db Switch 5 Suppression 1db Tri-function 6-degree isolation 20db Harmonic effects -73dbm

[0046] The signal output by LTE B3 is amplified by power amplifier 2, and the interference intensity is -12dBm. After being suppressed by duplexer 4, the interference intensity is 40dB. After being suppressed by switch 5, the interference intensity is 1dB. After being isolated by tripplexer 6, the interference intensity is 20dB. The final harmonic effect is -73dBm.

[0047] In this scheme, in order to reduce the interference of LTE B3 second harmonic on the n77 / 78 received signal, a Chebyshev circuit 3 is added after the output of power amplifier 2 to suppress the strength of LTE B3 second harmonic signal, thereby eliminating the interference factors on the n77 / 78 received signal.

[0048] like Figure 2 As shown, Chebyshev circuit 3 consists of an LC low-pass filter circuit, a resonant circuit, and an inductor. The resonant circuit is connected in parallel with the LC low-pass filter circuit, and the inductor is connected in series with the LC low-pass filter circuit. There are one or more resonant circuits, and only one series inductor.

[0049] Inductor L3 is connected to diode Z2. Inductors L2 and L1 are connected to inductor L3. Inductors L2 and L1 are connected in parallel. Capacitor C1 is connected to inductor L1. Capacitor C2 is connected to inductor L2. Diode Z1 and capacitor C1 are connected in parallel to inductor L1.

[0050] Capacitor C1 is 1pF, capacitor C2 is 1.5pF, inductor L1 is 5.1H, inductor L2 is 1.5H, and inductor L3 is 3H.

[0051] LC low-pass filter circuit: Composed of inductor L1, capacitor C1, and diodes Z2 and Z1, with inductor L1 and capacitor C1 connected in series. When using only the LC low-pass filter circuit, harmonic suppression is insufficient, and insertion loss is relatively large.

[0052] Based on the LC low-pass filter circuit, a parallel resonant circuit is added: inductor L2 and capacitor C2 are added, with inductor L2 connected in parallel with inductor L1. After adding the parallel resonant circuit, the harmonics are improved, suppressed to above 25dB, but the passband does not converge, and the insertion loss is relatively large. There can be one or multiple resonant circuits. Connecting the inductors of multiple resonant circuits in parallel with the inductor of the LC low-pass filter circuit aims to better address the interference problem of the second harmonic of LTE system 1 on the receiving sensitivity of receiver module 8. The series inductor is singular, further increasing the interference strength.

[0053] Based on the addition of a parallel resonant circuit, a series inductor is added: a series inductor L3 is added, and inductor L3 is connected in series with inductors L1 and L2.

[0054] like Figure 3 As shown in the Smith chart, adding a series inductor can tune the passband frequency to the 50-ohm convergence point. After passing through the complete filter circuit, the change in the 3.5GHz signal strength is as follows: Figure 4 and Figure 5 As shown.

[0055] Adding Chebyshev circuit 3 throughout the entire circuit network reduces the second harmonic distortion (DHD) at n77 / 78 to -103 dBm, meeting the 3GPP requirement that the single-channel receiver sensitivity of n77 / 78 be less than -80.8 dBm. The attenuation for the main frequency range of 1.71 GHz to 1.78 GHz is only less than 0.01 dB, as shown in Table 2.

[0056] Table 2 shows the intensity of interference to n77 / 78 when using Chebyshev circuit 3.

[0057] Interference intensity of n77 / 78 Power Amplifier 2 Output -12dbm Chebyshev circuit suppression 30db Duplexer 4 suppression 40db Switch 5 Suppression 1db Tri-function 6-degree isolation 20db Harmonic effects -103dBm

[0058] The signal output by LTE B3 is amplified by power amplifier 2, and the interference intensity is -12dBm. After being suppressed by Chebyshev circuit 3, the interference intensity is 30dB. After being suppressed by duplexer 4, the interference intensity is 40dB. After being suppressed by switch 5, the interference intensity is 1dB. After being isolated by tripplexer 6, the interference intensity is 20dB. The final harmonic effect is -103dBm.

[0059] The applicable frequency band range can be changed by adjusting the number of Chebyshev circuits 3, the number of resonant circuits, or the component values ​​of Chebyshev circuits 3. Without changing the connection method and components, the applicable frequency band can be changed by adjusting the number, or the applicable frequency band can be changed by directly adjusting the component values. The applicable frequency band range is from 1.4 GHz to 10 GHz.

[0060] By adding a Chebyshev circuit 3 after the output of power amplifier 2, the problem of excessive harmonic signal strength in one frequency band interfering with other frequency bands and causing performance degradation in the interfered frequency band can be solved. The Chebyshev circuit 3 can replace a dedicated filter, reducing costs. The component values ​​of the Chebyshev circuit 3 are adjustable, not limited to a specific frequency band, and have a wide range of applications, applicable from 1.4GHz to 10GHz. In addition to adjusting component values, several Chebyshev circuits 3 can also be connected in series or parallel to adjust the suppression effect of the secondary filter.

Claims

1. A system for resolving ENDC combinational coexistence interference using Chebyshev circuits, characterized in that, include: LTE system, used for outputting signals; Power amplifier, used to amplify signals and connect to LTE systems; The Chebyshev circuit, used to suppress the intensity of second harmonic signals, is connected to a power amplifier. It consists of an LC low-pass filter circuit, a resonant circuit, and a series inductor. The resonant circuit is connected in parallel with the LC low-pass filter circuit, and the series inductor is connected in series with the LC low-pass filter circuit. When only the LC low-pass filter circuit is used, the harmonic suppression of the Chebyshev circuit is insufficient, and the insertion loss is relatively large. Based on the LC low-pass filter circuit, a parallel resonant circuit is added, including adding inductor L2 and capacitor C2. Inductor L2 and inductor L1 are connected in parallel. After adding the parallel resonant circuit, the harmonic suppression is above 25dB. The resonant circuit is composed of an inductor and a capacitor connected in series. The inductor of the resonant circuit is connected in parallel with the inductor of the LC low-pass filter circuit. Based on the addition of the parallel resonant circuit, a series inductor L3 is added. The series inductor L3 is connected in series with inductors L1 and L2. A duplexer is used to isolate transmitted and received signals, ensuring that both transmission and reception can work normally at the same time. It is connected to a Chebyshev circuit. A switch is used to control opening and closing, and connects to a duplexer; A tripod is used to isolate the transmitted and received signals, ensuring that both transmission and reception can work normally at the same time, and it connects to a switch; Antenna interface, used to connect the antenna and the tripod; The receiving module is used to receive signals and connect to the tripod.

2. The system for resolving ENDC combinational coexistence interference using Chebyshev circuits according to claim 1, characterized in that, The Chebyshev circuit may be one or more, and the multiple Chebyshev circuits may be connected in series or in parallel.

3. A system for resolving ENDC combinational coexistence interference using Chebyshev circuits according to claim 1, characterized in that, The applicable frequency band range is adjusted based on the number of Chebyshev circuits, the number of resonant circuits, or the component values ​​of the Chebyshev circuits. The applicable frequency band range is from 1.4 GHz to 10 GHz.

4. A system for resolving ENDC combinational coexistence interference using a Chebyshev circuit according to claim 3, characterized in that, The Chebyshev circuit is added throughout the entire circuit network, reducing the second harmonic effect of n77 / 78 to -103 dBm, and the single-channel receiver sensitivity of n77 / 78 is less than -80.8 dBm, while the attenuation of the main frequency of 1.71 GHz to 1.78 GHz does not exceed 0.01 dB.

5. A system for resolving ENDC combinational coexistence interference using Chebyshev circuits according to claim 1, characterized in that, The receiving module is one or more of the following: SAW filter, LTCC filter, and IPD filter.

6. A system for resolving ENDC combinational coexistence interference using a Chebyshev circuit according to claim 5, characterized in that, The system changes the applicable frequency band range by adjusting the number of Chebyshev circuits, the number of resonant circuits, or the component values ​​of the Chebyshev circuits. Without changing the connection method and components, the applicable frequency band can be changed by adjusting the number or by directly adjusting the component values. The applicable frequency band range is from 1.4 GHz to 10 GHz.

7. A system for resolving ENDC combinational coexistence interference using Chebyshev circuits according to claim 1, characterized in that, In the Chebyshev circuit, the series inductor L3 is connected to the diode Z2, the inductors L2 and L1 are connected to the series inductor L3, the inductors L2 and L1 are connected in parallel, the capacitor C1 is connected to the inductor L1, the capacitor C2 is connected to the inductor L2, and the diode Z1 and the capacitor C1 are connected in parallel to the inductor L1.

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