Radio frequency transmitting circuits and electronic devices

Abstract

The present invention relates to a communications technology field, and provides a low-cost radio frequency transmission circuit and electronic device capable of easily introducing a DC signal into a radio frequency line to support a wide radio frequency bandwidth. The radio frequency transmission circuit includes: a first radio frequency input terminal and a DC blocking capacitor, wherein a first terminal of the DC blocking capacitor is electrically connected to the first radio frequency input terminal; a first LC filter, wherein an input terminal of the first LC filter is electrically connected to a second terminal of the DC blocking capacitor and an output terminal of the first LC filter is electrically connected to an output terminal of the radio frequency transmission circuit, the first LC filter being a low-pass filter; and a DC input terminal and a ferrite bead, wherein the DC input terminal is electrically connected to the input terminal of the first LC filter or between two inductors of the first LC filter via the ferrite bead.

Description

[Technical Field]

[0001] [Related Applications] This application claims priority to Chinese Patent Application No. 202211487510.7, entitled "RADIO FREQUENCY TRANSMISSION CIRCUIT AND ELECTRONIC DEVICE," filed with the State Intellectual Property Office of China on November 24, 2022, which is incorporated herein by reference in its entirety.

[0002] [Technical field] This application relates to the field of communications technology, and more particularly to radio frequency transmitting circuits and electronic devices. [Background technology]

[0003] A bias-tee (Bias-T) is an operating circuit for cascading modules on the base station side and is usually used at the output end of an external interface. Bias-Ts can inject DC signals into the transmission radio frequency (RF) signal cable. As shown in Figure 1, traditional Bias-Ts use an inductor and capacitor design solution, injecting DC (Direct Current) signals into the radio frequency (RF) signal line. Using a conventional inductor significantly limits the RF bandwidth, preventing the Bias-T from being applicable to a wide bandwidth. Alternatively, tapered inductors can be used, which achieves a wide RF bandwidth. However, these components have a special shape and are fragile. They cannot be manufactured by surface mounting, and are easily damaged during processing, assembly, and production debugging. Therefore, after the entire module is surface mounted, manual repair welding is required to complete the entire assembly, which increases costs. Summary of the Invention

[0004] The technical solution of the present application provides a low-cost radio frequency transmitting circuit and electronic device that can inject a DC signal into a radio frequency line in a simple way to accommodate a wide radio frequency bandwidth.

[0005] According to a first aspect, there is provided a radio frequency transmitter circuit, comprising: a first radio frequency input and a DC blocking capacitor, a first end of the DC blocking capacitor electrically connected to the first radio frequency input; a first LC filter, an input terminal of the first LC filter electrically connected to the second terminal of the DC blocking capacitor, an output terminal of the first LC filter electrically connected to an output terminal of the radio frequency transmission circuit, and the first LC filter being a low-pass filter; a DC input terminal and a ferrite bead, wherein the DC input terminal is electrically connected to an input terminal of the first LC filter or between two inductors of the first LC filter via a ferrite bead; a radio frequency transmitter circuit including:

[0006] In a possible implementation, the first LC filter comprises: a first filter inductor, a first end of which is an input end of the first LC filter; a second filter inductor, a first end of the second filter inductor electrically connected to the second end of the first filter inductor, and the second end of the second filter inductor being an output end of the first LC filter; a filter capacitor connected in series between the second end of the first filter inductor and a ground; The DC input terminal is electrically connected to a first terminal of the first filter inductor or a second terminal of the first filter inductor via the ferrite bead.

[0007] In one possible implementation, the radio frequency transmitter circuit further includes a second radio frequency input terminal, the second radio frequency input terminal and the first radio frequency input terminal being coupled and then electrically connected to the first terminal of the DC blocking capacitor.

[0008] In one possible implementation, the radio frequency transmission circuit further includes a third radio frequency input terminal and a second LC filter, the input terminal of the second LC filter being electrically connected to the third radio frequency input terminal, and the output terminal of the second LC filter and the output terminal of the first LC filter being coupled and electrically connected to the output terminal of the radio frequency transmission circuit.

[0009] In a possible implementation, the second LC filter is a high-pass filter.

[0010] In one possible implementation, the radio frequency transmitter circuit further includes a fourth radio frequency input, the fourth radio frequency input and the third radio frequency input being coupled and then electrically connected to an input of the second LC filter.

[0011] In one possible implementation, the DC input terminal is electrically connected to the second terminal of the first filter inductor via the ferrite bead, and the second filter inductor has a through current range of 2 A or more.

[0012] In one possible implementation, the DC input terminal is electrically connected to a first terminal of the first filter inductor via the ferrite bead, and a through current range of the first filter inductor and the second filter inductor is 2 A or more.

[0013] In a possible implementation, the DC blocking capacitor and the filter capacitor have a withstand voltage of 50V or more.

[0014] In a possible implementation, the first filter inductor and the second filter inductor are variable inductors; The filter capacitor is a variable capacitor.

[0015] In a possible implementation, the radio frequency transmission circuit further includes a third inductor connected in series between the DC input and the ferrite bead.

[0016] According to a second aspect, there is provided an electronic device, the electronic device including the radio frequency transmission circuit described above.

[0017] According to an embodiment of the radio frequency transmitter circuit and electronic device of the present application, a first LC filter for low-pass filtering is connected in series between a first radio frequency input terminal and an output terminal. A DC signal is introduced into the first LC filter via a ferrite bead. Ferrite beads have a larger impedance at low frequencies than inductors, thereby reducing crosstalk on the DC path of low-frequency signals from the first radio frequency input terminal. Furthermore, the use of the first LC filter can suppress adverse effects on the DC path of signals after the first LC filter, allowing higher-frequency signals to be introduced after the first LC filter to accommodate a wide radio frequency bandwidth. Furthermore, a DC blocking capacitor is disposed between the first radio frequency input terminal and the first LC filter to prevent the introduced DC signal from adversely affecting the first radio frequency input terminal. Furthermore, because a tapered inductor is not required and the DC signal is easily introduced into the radio frequency line, the processing process is simple, no special processes are required, and low cost is achieved. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a circuit diagram of a Bias-T in the prior art.

[0019] [Figure 2] 1 is a structural diagram of a radio frequency transmitting circuit according to an embodiment of the present application;

[0020] [Figure 3] FIG. 10 is a structural diagram of another radio frequency transmitting circuit according to an embodiment of the present application;

[0021] [Figure 4] FIG. 10 is a structural diagram of another radio frequency transmitting circuit according to an embodiment of the present application;

[0022] [Figure 5] FIG. 10 is a structural diagram of another radio frequency transmitting circuit according to an embodiment of the present application;

[0023] [Figure 6] FIG. 10 is a structural diagram of another radio frequency transmitting circuit according to an embodiment of the present application;

[0024] [Figure 7] FIG. 10 is a structural diagram of another radio frequency transmitting circuit according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0025] The terms used in the embodiments of the present application are merely used to describe particular embodiments of the present application and are not intended to limit the present application.

[0026] The technical solutions in the embodiments of the present application are applicable to various communication systems, such as long term evolution (LTE) systems, fifth generation (5G) systems, etc. thThis technology can be applied to 5G (5G generation) mobile communication systems and future mobile communication systems. As shown in FIG. 2 , an embodiment of the present application provides a radio frequency transmission circuit including: a first radio frequency input terminal RF1 and a DC blocking capacitor C1, where a first terminal (i.e., a left terminal) of the DC blocking capacitor C1 is electrically connected to the first radio frequency input terminal RF1; a first LC filter 10, where an input terminal of the first LC filter 10 is electrically connected to a second terminal (i.e., a right terminal) of the DC blocking capacitor C1 and an output terminal of the first LC filter 10 is electrically connected to an output terminal O of the radio frequency transmission circuit, where the first LC filter 10 is a low-pass filter; and a DC input terminal DC and a ferrite bead M, where the DC input terminal DC is electrically connected to the input terminal of the first LC filter 10 via the ferrite bead M or the DC input terminal DC is electrically connected between two inductors of the first LC filter 10 via the ferrite bead M. That is, the DC signal introduced by the DC input terminal DC and the ferrite bead M must be combined with the radio frequency signal input by the first radio frequency input terminal RF1, and then transmitted to the output terminal O of the radio frequency transmitting circuit via at least a part of the first LC. That is, the above circuit configuration realizes the function of Bias-T, and the DC signal is introduced into the radio frequency path, combined with the radio frequency signal, and output.

[0027] Specifically, an LC filter, also known as a passive filter, is a filter circuit formed by a combination of inductors and capacitors. The first LC filter 10 is a low-pass filter configured to pass low-frequency or DC components in a signal and suppress high-frequency components, interference, and noise. A low-frequency radio frequency signal can be input to the first radio frequency input terminal RF1. The high-frequency suppression effect of the first LC filter 10 reduces the frequency band required for the high impedance of the ferrite bead M, and the ferrite bead M only needs to maintain high impedance in the low-frequency band. In other words, the low-frequency signal input to the first radio frequency input terminal RF1 does not generate crosstalk into the DC path of the ferrite bead M, and the ferrite bead M has little impact on the performance of the radio frequency path. The high-frequency suppression feature of at least some of the inductors in the first LC filter 10 can suppress the formation of resonance between the DC path and the radio frequency path. In other words, the adverse effect of signals in the path after the first LC filter 10 on the DC path can be suppressed. In this way, high frequency signals can be introduced after the first LC filter 10 to accommodate a wide radio frequency bandwidth.

[0028] According to this embodiment of the radio frequency transmitter circuit, a first LC filter for low-pass filtering is connected in series between a first radio frequency input terminal and an output terminal. A DC signal is introduced into the first LC filter via a ferrite bead. Ferrite beads have a larger impedance at low frequencies than inductors, thereby reducing crosstalk on the DC path of low-frequency signals from the first radio frequency input terminal. Furthermore, the use of the first LC filter can suppress adverse effects on the DC path of signals after the first LC filter, allowing higher-frequency signals to be introduced after the first LC filter to accommodate a wide radio frequency bandwidth. Furthermore, a DC blocking capacitor is disposed between the first radio frequency input terminal and the first LC filter to prevent the introduced DC signal from adversely affecting the first radio frequency input terminal. Furthermore, because a tapered inductor is not required and the DC signal is easily introduced into the radio frequency line, the processing process is simple, no special processes are required, and low cost is achieved.

[0029] 3, the first LC filter 10 includes a first filter inductor L1, the first end (i.e., left end) of which is the input end of the first LC filter 10, a second filter inductor L2, the first end (i.e., left end) of which is electrically connected to a second end (i.e., right end) of the first filter inductor L1, and the second end (i.e., right end) of the second filter inductor L2 is the output end of the first LC filter 10, and a filter capacitor C2, the filter capacitor C2 is connected in series between the second end of the first filter inductor L1 and a ground end. Note that the specific embodiment of the ground end is not limited to this embodiment of the present application, as long as it can provide a potential, a current loop is formed in a circuit based on the ground end, and the circuit operates normally. The DC input terminal DC is electrically connected to the second end of the first filter inductor L1 via a ferrite bead M, or as shown in FIG. 4, the DC input terminal DC is electrically connected to the first end of the first filter inductor L1 via a ferrite bead M.

[0030] In a possible implementation, as shown in Figure 3 or 4, the radio frequency transmitting circuit further includes a second radio frequency input terminal RF2. The second radio frequency input terminal RF2 and the first radio frequency input terminal RF1 are coupled and then electrically connected to a first terminal of a DC blocking capacitor C1. A low-frequency radio frequency signal is input to both the first radio frequency input terminal RF1 and the second radio frequency input terminal RF2, and after being coupled, is combined with a DC signal introduced through the ferrite bead M via the DC blocking capacitor C1.

[0031] In a possible implementation, as shown in FIG. 3 or 4, the radio frequency transmission circuit further includes a third radio frequency input terminal RF3 and a second LC filter. The input terminal of the second LC filter 20 is electrically connected to the third radio frequency input terminal RF3, and the output terminal of the second LC filter 20 and the output terminal of the first LC filter 10 are coupled and electrically connected to the output terminal O of the radio frequency transmission circuit. That is, the signal ultimately synthesized and output by the radio frequency transmission circuit includes radio frequency signals from the first radio frequency input terminal RF1, the second radio frequency input terminal RF2, and the third radio frequency input terminal RF3, and a DC signal from the DC input terminal DC. The high-frequency suppression characteristics of at least some of the inductors of the first LC filter 10 suppress the adverse effect of the radio frequency signal from the third radio frequency input terminal RF3 on the ferrite bead M in the circuit on the DC path. This allows higher-frequency signals to be introduced via the third radio frequency input terminal RF3, enabling a larger radio frequency bandwidth to be accommodated. 3, the second filter inductor L2 can suppress the adverse effects of the radio frequency signal from the third radio frequency input port RF3 on the ferrite bead M on the DC path. In the configuration shown in Fig. 4, the first filter inductor L1 and the second filter inductor L2 can suppress the adverse effects of the radio frequency signal from the third radio frequency input port RF3 on the ferrite bead M.

[0032] In a possible implementation, as shown in Figure 3 or 4, the second LC filter 20 is a high-pass filter, and a high-frequency signal can be input to the third radio frequency input terminal RF3. The entire radio frequency transmitting circuit can combine and transmit a total of four signals, including a low-frequency signal, a high-frequency signal, and a DC signal, thereby reducing the amount of external interfaces, simplifying the transmitting circuit configuration, and reducing costs.

[0033] In a possible implementation, as shown in FIG. 4, a DC input terminal DC is electrically connected to the second terminal of a first filter inductor L1 via a ferrite bead M. The through-current range of the second filter inductor L2 is 2 A or more. In the circuit configuration shown in FIG. 4, the second filter inductor L2 is used to suppress resonance between the DC path in which the ferrite bead M is located and the radio frequency path in which the second LC filter 20 is located. Therefore, the through-current range of the second filter inductor L2 is set large to reduce the adverse effects of large currents on the radio frequency path in which the second LC filter 20 is located.

[0034] In a possible implementation, as shown in FIG. 3, a DC input terminal DC is electrically connected to a first terminal of a first filter inductor L1 via a ferrite bead M. The first filter inductor L1 and the second filter inductor L2 have a through-current range of 2 A or more. In the circuit configuration shown in FIG. 3, the first filter inductor L1 and the second filter inductor L2 are used together to suppress resonance between the DC path in which the ferrite bead M is located and the radio frequency path in which the second LC filter 20 is located. Therefore, the first filter inductor L1 and the second filter inductor L2 are configured to have a large through-current range in order to reduce the adverse effects of large currents on the radio frequency path in which the second LC filter 20 is located.

[0035] In a possible implementation, the DC blocking capacitor C1 and the filter capacitor C2 have a withstand voltage of 50V or more to reduce adverse effects on the radio frequency path after the DC path where the ferrite bead M is located is introduced.

[0036] 3 and 4, two low-frequency signals supplied from the first radio frequency input terminal RF1 and the second radio frequency input terminal RF2 are combined and pass through the first LC filter 10. The first LC filter 10 mainly eliminates the influence of high-frequency signals on the two low-frequency signals. That is, the first LC filter 10 has both the ability to suppress high-frequency radio frequency signals and the ability to allow DC signals to pass through. The pass-through capability is improved by selecting the pass-through capability of at least some of the filter inductors of the first LC filter 10 and the withstand voltage capabilities of the DC blocking capacitor C1 and the filter capacitor C2.

[0037] In a possible implementation, the first filter inductor L1 and the second filter inductor L2 are variable inductors and the filter capacitor C2 is a variable capacitor.

[0038] According to the radio frequency transmitter circuit of this embodiment of the present application, the DC path is connected in series with the ferrite bead M, which is then connected to the first LC filter 10 or the input terminal of the first LC filter 10. Generally, the ferrite bead M can maintain a high impedance state for AC signals in the 4G frequency band. By isolating the radio frequency signal in the first LC filter 10, the ferrite bead M establishes a direct connection with the radio frequency path only in the low frequency band. Since the ferrite bead M in this frequency band is in a high impedance state, the impact of the ferrite bead M on the performance of the radio frequency path in the entire frequency band is minimal. At least some of the inductors in the first LC filter 10 are set to inductors with large through-current capability, and the capacitance and inductance values ​​of the first LC filter 10 can be fine-tuned by taking advantage of the high robustness of the first LC filter 10 to improve the first LC filter's ability to suppress radio frequency signals. The DC blocking capacitor C1 and filter capacitor C2, which are directly connected to the DC path where the ferrite bead M is located, are selected to have high voltage resistance, further reducing the adverse effects of the DC path being introduced into the radio frequency path. The circuit configuration is simple, and the selected components are common components with heat resistance and voltage resistance. Signal transmission from DC to 7 GHz can be achieved without using similar inductor-type vulnerable components. The processing process is simple, does not require special or complex processes, and is low cost.

[0039] In a possible implementation, as shown in FIG. 5 , the radio frequency transmitter circuit further includes a fourth radio frequency input terminal RF4. The fourth radio frequency input terminal RF4 and the third radio frequency input terminal RF3 are coupled and then electrically connected to the input terminal of the second LC filter 20. That is, the radio frequency path in which the second LC filter 20 is located may transmit a signal obtained by combining radio frequency signals from multiple radio frequency input terminals, and the radio frequency signals input to the third radio frequency input terminal RF3 and the fourth radio frequency input terminal RF4 may be high-frequency signals. It is understood that in another possible implementation, more radio frequency input terminals may be electrically connected to the input terminal of the second LC filter 20. That is, the amount of radio frequency signals coupled onto the radio frequency path in which the second LC filter 20 is located is not limited by this embodiment of the present application. Similarly, more radio frequency input terminals may be electrically connected to the input terminal of the first LC filter 10. For example, the radio frequency transmitter circuit further includes a fifth radio frequency input terminal RF5. The fifth radio frequency input port RF5, the first radio frequency input port RF1, and the second radio frequency input port RF2 are coupled together and then electrically connected to the input port of the first LC filter 10. Low-frequency signals may be input to the first radio frequency input port RF1, the second radio frequency input port RF2, and the fifth radio frequency input port RF5. That is, the amount of radio frequency signals coupled onto the radio frequency path through the first LC filter 10 is not limited in this embodiment. That is, for any combination of multi-frequency signals and DC signals, the LC filter can be used to perform corresponding differentiation, and then ferrite beads can be introduced and connected to the LC filter structure to achieve the purpose of coupling the DC path and the radio frequency path.

[0040] In a possible implementation, as shown in FIGS. 6 and 7, the radio frequency transmitter circuit further includes a third inductor L3 connected in series between the DC input terminal DC and the ferrite bead M. The third inductor L3 is configured to increase the frequency of the radio frequency signal introduced at the input terminal of the first LC filter 10. For example, after introducing a second radio frequency input terminal RF2 coupled to the first radio frequency input terminal RF1, the bandwidth of the path through which the first LC filter 10 is located increases. If the increased bandwidth cannot meet the requirements of the ferrite bead M, the third inductor L3 may be further connected in series between the ferrite bead M and the DC input terminal DC so that the equivalent impedance of the third inductor L3 and the ferrite bead M after the series connection can accommodate a larger bandwidth after coupling. Furthermore, after the third inductor L3 is further connected in series between the DC input terminal DC and the ferrite bead M, the through-current range of the third inductor L3 may be set to 2 A or more. That is, the through-current range of the third inductor L3 is set to be large to reduce the adverse effects of large currents on the radio frequency path through which the second LC filter 20 is located. Therefore, it is not necessary to set the through current range of the second filter inductor L2 in FIG. 6 large, and it is also not necessary to set the through current range of the first filter inductor L1 and the second filter inductor L2 in FIG. 7 large.

[0041] An embodiment of the present application further provides an electronic device including the radio frequency transmission circuit of any of the above embodiments.

[0042] The electronic device may be any network device with a radio frequency transmission function. For example, in a scenario where small cell signals are cascaded, two low frequency signals, one DC signal, and one radio frequency signal need to be combined into one signal for external transmission. The network device in this scenario may include the radio frequency transmission circuit of this embodiment of the present application.

[0043] The network device may be, for example, an access network device. The access network device may also be called a radio access network (RAN) device and is a device that provides wireless communication functions to terminal devices. Examples of the access network device include, but are not limited to, a next-generation NodeB (gNB), an evolved NodeB (eNB), a baseband unit (BBU), a transmission reception point (TRP), a transmission point (TP) in 5G, a base station in a future mobile communication system, or an access point in a Wi-Fi system. Alternatively, the access network device may be a radio controller, a central unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario. Alternatively, the network device may be a relay station, an in-vehicle device, a network device in a future evolved PLMN network, etc. Alternatively, the network device may be a network device in a future 6G network, etc. The network device may be a macro base station or a micro base station, and the coverage area of ​​the network device may include one cell or multiple cells.

[0044] In an embodiment of the present application, the device configured to implement the functions of the network device may be a network device, or may be a device that can assist the network device to implement the functions, such as a chip system.

[0045] In the embodiments of the present application, "at least one" means one or more, and "multiple" means two or more. "And / or" describes an association relationship that describes associated objects and indicates that three relationships may exist. For example, A and / or B may represent three cases: only A is present, both A and B are present, and only B is present. A and B may be singular or plural. The character " / " typically indicates an "or" relationship between associated objects. "At least one of" or similar expressions represents any combination of items, including any combination of a single item or multiple items. For example, at least one of a, b, and c may represent a, b, c, ab, ac, bc, or abc, where a, b, and c may be singular or plural.

[0046] The above description is merely an exemplary embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent replacements, or improvements made without departing from the spirit and principle of the present application should be encompassed within the protection scope of the present application.

Claims

1. 1. A radio frequency transmitter circuit, comprising: a first radio frequency input and a DC blocking capacitor, a first end of the DC blocking capacitor electrically connected to the first radio frequency input; a first LC filter, an input terminal of the first LC filter electrically connected to the second terminal of the DC blocking capacitor, an output terminal of the first LC filter electrically connected to an output terminal of the radio frequency transmission circuit, and the first LC filter being a low-pass filter; a DC input terminal and a ferrite bead, the DC input terminal being electrically connected to an input terminal of the first LC filter or between two inductors of the first LC filter via a ferrite bead; a radio frequency transmitting circuit including:

2. The first LC filter is a first filter inductor, a first end of which is an input end of the first LC filter; a second filter inductor, a first end of the second filter inductor electrically connected to the second end of the first filter inductor, and the second end of the second filter inductor being an output end of the first LC filter; a filter capacitor connected in series between the second end of the first filter inductor and ground; Including, 2. The radio frequency transmitter circuit according to claim 1, wherein the DC input terminal is electrically connected to the first end of the first filter inductor or the second end of the first filter inductor via the ferrite bead.

3. a second radio frequency input, the second radio frequency input and the first radio frequency input being coupled together and electrically connected to the first end of the DC blocking capacitor; 3. The radio frequency transmitter circuit of claim 2, further comprising:

4. a third radio frequency input terminal; a second LC filter, an input end of the second LC filter electrically connected to the third radio frequency input end, an output end of the second LC filter and an output end of the first LC filter coupled to each other and electrically connected to an output end of the radio frequency transmission circuit; The radio frequency transmitter circuit according to any one of claims 1 to 3, further comprising:

5. 5. The radio frequency transmitter circuit of claim 4, wherein the second LC filter is a high-pass filter.

6. a fourth radio frequency input terminal, wherein the fourth radio frequency input terminal and the third radio frequency input terminal are coupled and electrically connected to the input terminal of the second LC filter; 5. The radio frequency transmitter circuit of claim 4, further comprising:

7. the DC input terminal is electrically connected to the second terminal of the first filter inductor via the ferrite bead; The through current range of the second filter inductor is 2A or more; 3. The radio frequency transmitter circuit of claim 2.

8. the DC input terminal is electrically connected to the first terminal of the first filter inductor via the ferrite bead; The through current range of the first filter inductor and the second filter inductor is 2 A or more; 3. The radio frequency transmitter circuit of claim 2.

9. 3. The radio frequency transmission circuit according to claim 2, wherein the DC blocking capacitor and the filter capacitor have a withstand voltage of 50 V or more.

10. the first filter inductor and the second filter inductor are variable inductors; the filter capacitor is a variable capacitor; 3. The radio frequency transmitter circuit of claim 2.

11. a third inductor connected in series between the DC input terminal and the ferrite bead; The radio frequency transmitter circuit according to any one of claims 1 to 10, further comprising:

12. An electronic device comprising a radio frequency transmission circuit according to any one of claims 1 to 11.

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