Anti-blocking low noise amplifier and radio frequency front end
By connecting the multi-resonant network in parallel at the input and output ends of the low-noise amplification transistor, the blocking problem caused by signal leakage in the FDD communication system is solved, which significantly improves the anti-blocking capability and improves the overall performance of the system.
Patent Information
- Application Number
- CN202421622095.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-10
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2034-07-10
AI Technical Summary
In the FDD communication system, signal leakage of the transmit link and the receiving link leads to blocking. The prior art solves the problem by increasing antenna isolation or enhancing the transmission suppression ratio. However, these methods will lead to an increase in the antenna array, a decrease in radiation efficiency or an increase in the reception link loss, deteriorating the noise factor, and reducing the reception sensitivity.
By connecting the multi-resonant network in parallel at the input and output ends of the low-noise amplification transistor, the multi-resonant network presents an open circuit in the receiving frequency band and a short circuit in the transmit frequency band, thereby improving the anti-blocking capability of the low-noise amplification.
It significantly improves the anti-blocking capability of low-noise amplifier, avoids the low-noise amplifier transistor entering the current saturation and voltage saturation state due to transmitting leaked signals, and improves the overall performance of the FDD communication system.
Smart Images
Figure CN222802833U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of communications, in particular to an anti-blocking low-noise amplifier and a radio frequency front end. Background Art
[0002] In a frequency division duplex (FDD) system, the transmitting link and the receiving link work simultaneously. Since the power of the transmitting signal is much greater than the power of the receiving signal, the power leaked from the transmitting link to the receiving link can easily push the receiving link to a saturated state, thereby affecting the normal amplification of the receiving signal. This phenomenon is called blocking. Figure 1 The figure shows the RF front-end structure of the FDD communication system, including a power amplifier (PA), a low noise amplifier (LNA), a transmit filter, and a receive filter. In order to avoid the occurrence of blocking, the current FDD communication system usually applies two technical solutions. The first solution is to increase the isolation between the transmit antenna and the receive antenna, and the second solution is to increase the transmit suppression ratio of the receive filter. However, both solutions have obvious problems. The first solution will lead to an increase in the antenna array and a decrease in radiation efficiency, and the second solution will increase the loss of the receive link, deteriorate the noise coefficient, and thus reduce the receive sensitivity. Summary of the invention
[0003] In order to solve the above problems in the prior art, the utility model provides an anti-blocking low noise amplifier and a radio frequency front end, which improve the anti-blocking capability of the low noise amplifier itself, thereby improving the comprehensive performance of the FDD communication system.
[0004] On the one hand, the utility model provides an anti-blocking low-noise amplifier, comprising an input matching network, a low-noise amplifier transistor and an output matching network connected in sequence, and also comprising an input multi-resonance network and an output multi-resonance network, wherein one end of the input multi-resonance network is connected between the input matching network and the input end of the low-noise amplifier transistor, and the other end is grounded; one end of the output multi-resonance network is connected between the output end of the low-noise amplifier transistor and the output matching network, and the other end is grounded.
[0005] Furthermore, the input multi-resonance network and the output multi-resonance network are both open-circuited in a receiving frequency band and short-circuited in a transmitting frequency band.
[0006] Furthermore, when the transmitting frequency is greater than the receiving frequency, the structure of the input multi-resonance network and the output multi-resonance network is set to include a first inductor, a second inductor and a first capacitor, wherein the first inductor and the first capacitor form a series resonant network and are then connected in parallel with the second inductor.
[0007] When the transmitting frequency is lower than the receiving frequency, the structure of the input multi-resonance network and the output multi-resonance network is set to include a second capacitor, a third capacitor and a third inductor, wherein the second capacitor and the third inductor form a parallel resonant network, and the third inductor is connected in series with the parallel resonant network.
[0008] Furthermore, the low noise amplifier transistor is a single-tube structure, including a common-source transistor, wherein the source of the common-source transistor includes an inductor.
[0009] Furthermore, the common-source transistor is a field effect transistor or a bipolar transistor.
[0010] Furthermore, the low noise amplifier transistor is a common source and common gate structure, comprising two transistors, wherein the source of the first transistor is connected to the drain of the second transistor, and the source of the second transistor comprises an inductor.
[0011] Furthermore, the first transistor and / or the second transistor is a field effect transistor or a bipolar transistor.
[0012] Another aspect of the utility model provides a radio frequency front end, comprising a transmitting branch and a receiving branch, wherein the receiving branch comprises an anti-blocking low noise amplifier in any of the above technical solutions.
[0013] The input and output ends of the low noise amplifier transistor of the utility model both use a multi-resonance network. The network is open-circuited in the receiving frequency band and does not affect the impedance matching of the low noise amplifier transistor. It is short-circuited in the transmitting frequency band, which can prevent the low noise amplifier transistor from being pushed to the current saturation and voltage saturation state by the transmission leakage signal, thereby significantly improving the anti-blocking ability of the low noise amplifier. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0015] Figure 1 It is a structure diagram of the radio frequency front end of the FDD communication system in the prior art;
[0016] Figure 2 This is a schematic diagram of the structure of an anti-blocking low noise amplifier according to an embodiment of the utility model;
[0017] Figure 3(a) shows Figure 2 A circuit structure diagram of a multi-resonance network used when the transmitting frequency is greater than the receiving frequency in the embodiment;
[0018] Figure 3(b) shows Figure 2 A circuit structure diagram of a multi-resonance network used when the transmitting frequency is lower than the receiving frequency in the embodiment;
[0019] Figure 4(a) shows Figure 2 A circuit diagram of a single-tube structure low-noise amplifier transistor in an embodiment;
[0020] FIG4( b ) is a circuit diagram of a low noise amplifier transistor in a cascode structure. DETAILED DESCRIPTION
[0021] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.
[0022] It should be noted that the terms "comprises" and "has" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatus.
[0023] In the present application, the terms "upper", "lower", "left", "right", "front", "back", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements, or components to have a specific direction, or to be constructed and operated in a specific direction. Moreover, in addition to being used to indicate directions or positional relationships, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in certain circumstances. For those of ordinary skill in the art, the specific meanings of these terms in the present application can be understood according to the specific circumstances.
[0024] As mentioned in the background technology, the RF front end of the traditional FDD communication system avoids blocking by increasing the isolation between the transmitting antenna and the receiving antenna or increasing the transmit suppression ratio of the receiving filter, but it also leads to the increase of the antenna array surface, the reduction of radiation efficiency and the increase of the loss of the receiving link, which deteriorates the noise coefficient and thus reduces the receiving sensitivity.
[0025] This embodiment adopts a new idea to improve the anti-blocking ability of the low noise amplifier by improving the structure of the low noise amplifier itself. The method adopted is as follows: an anti-blocking low noise amplifier includes an input matching network, a low noise amplifier transistor and an output matching network connected in sequence, and also includes an input multi-resonance network and an output multi-resonance network, wherein one end of the input multi-resonance network is connected between the input matching network and the input end of the low noise amplifier transistor, and the other end is grounded; one end of the output multi-resonance network is connected between the output end of the low noise amplifier transistor and the output matching network, and the other end is grounded. The specific structure is as follows: Figure 2 shown.
[0026] The main feature of this embodiment is that the input and output ends of the low noise amplifier transistor are connected in parallel with a multi-resonance network, and the multi-resonance network is open-circuited in the receiving (RX) frequency band and short-circuited in the transmitting (TX) frequency band.
[0027] In order to improve the anti-blocking ability of the LNA, on the one hand, it is necessary to reduce the transmission leakage signal at the input end of the LNA transistor as much as possible to prevent the LNA transistor from entering the current saturation state, and on the other hand, it is necessary to reduce the load impedance of the LNA transistor in the transmission frequency band as much as possible to prevent the LNA transistor from entering the voltage saturation state. Figure 2 In the embodiment, both the input multi-resonance network and the output multi-resonance network are short-circuited in the transmission frequency band, so the anti-blocking low noise amplifier proposed in the present invention can meet the requirements of both aspects at the same time, thereby achieving a significant improvement in the anti-blocking capability.
[0028] The circuit that can realize the above functions has two different structures according to the relationship between the transmitting frequency and the receiving frequency:
[0029] When the transmitting frequency (f TX ) is greater than the receiving frequency (f RX ), the structure of the input multi-resonance network and the output multi-resonance network is set as shown in Figure 3(a), including a first inductor L1, a second inductor L2 and a first capacitor C1, wherein the first inductor L1 and the first capacitor C1 are connected in series to form a series resonant network. At the transmitting frequency, the series resonant network is short-circuited, so the multi-resonance network is also short-circuited. At the receiving frequency, the series resonant network is equivalent to a capacitor, which is connected in parallel with the second inductor L2 to produce parallel resonance, so the multi-resonance network is open.
[0030] When the transmitting frequency (f TX ) is less than the receiving frequency (f RX), the structure of the input multi-resonance network and the output multi-resonance network is set as shown in FIG3(b), including the second capacitor C2, the third capacitor C3 and the third inductor L3, wherein the second capacitor C2 and the third inductor L3 form a parallel resonant network. At the receiving frequency, the parallel resonant network is open-circuited, so the multi-resonance network is also open-circuited. At the transmitting frequency, the parallel resonant network is equivalent to an inductor, which is connected in series with the third capacitor C3 to generate series resonance, so the multi-resonance network is short-circuited.
[0031] The low noise amplifier transistor in this embodiment may be a single-tube structure, as shown in FIG4( a ), and only includes a common source transistor, wherein the source of the common source transistor includes an inductor Ls.
[0032] The low noise amplifier transistor can also be a common source and common gate structure, as shown in FIG4(b), including two transistors, wherein the source of the first transistor is connected to the drain of the second transistor, and the source of the second transistor includes an inductor Ls. The inductors Ls in the two low noise amplifier transistors are used to align the input conjugate matching and input optimal noise matching of the transistors, which is a common practice in the art.
[0033] It is worth noting that the common source transistor in the single-transistor structure and the two transistors in the common source and common gate structure can both be field effect transistors (FETs) or bipolar junction transistors (BJTs).
[0034] This embodiment also provides a radio frequency front end, including a transmitting branch and a receiving branch, wherein the receiving branch includes the anti-blocking low noise amplifier in any of the above technical solutions.
[0035] It should also be noted that the resistors, inductors, and capacitors mentioned above do not refer to a specific electronic device, but can also be resistors, inductors, and capacitors that are equivalent to circuits built in parallel, series, or other ways.
[0036] The above description is only the preferred 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 modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. An anti-blocking low noise amplifier, comprising an input matching network, a low noise amplifier transistor and an output matching network connected in sequence, characterized in that: It also includes an input multi-resonance network and an output multi-resonance network, wherein one end of the input multi-resonance network is connected between the input matching network and the input end of the low-noise amplifier transistor, and the other end is grounded; one end of the output multi-resonance network is connected between the output end of the low-noise amplifier transistor and the output matching network, and the other end is grounded.
2. The anti-blocking low noise amplifier according to claim 1, characterized in that: The input multi-resonance network and the output multi-resonance network are both open circuit in the receiving frequency band and short circuit in the transmitting frequency band.
3. The anti-blocking low noise amplifier according to claim 2, characterized in that: When the transmitting frequency is greater than the receiving frequency, the structure of the input multi-resonance network and the output multi-resonance network is set to include a first inductor, a second inductor and a first capacitor, wherein the first inductor and the first capacitor form a series resonant network and are then connected in parallel with the second inductor.
4. The anti-blocking low noise amplifier according to claim 2, characterized in that: When the transmitting frequency is lower than the receiving frequency, the structure of the input multi-resonance network and the output multi-resonance network is set to include a second capacitor, a third capacitor and a third inductor, wherein the second capacitor and the third inductor form a parallel resonant network, and the third inductor is connected in series with the parallel resonant network.
5. The anti-blocking low noise amplifier according to claim 1, characterized in that: The low noise amplifier transistor is a single-tube structure, including a common source transistor, wherein the source of the common source transistor includes an inductor.
6. The anti-blocking low noise amplifier according to claim 5, characterized in that: The common source transistor is a field effect transistor or a bipolar transistor.
7. The anti-blocking low noise amplifier according to claim 1, characterized in that: The low noise amplifier transistor is a common source and common gate structure, comprising two transistors, wherein the source of the first transistor is connected to the drain of the second transistor, and the source of the second transistor comprises an inductor.
8. The anti-blocking low noise amplifier according to claim 7, characterized in that: The first transistor and / or the second transistor is a field effect transistor or a bipolar transistor.
9. A radio frequency front end, comprising a transmitting branch and a receiving branch, characterized in that: The receiving branch comprises the anti-blocking low noise amplifier according to any one of claims 1 to 8.