CN112865738B - Radio frequency receiving module, method for improving performance of radio frequency receiving module and communication equipment - Google Patents

Abstract

The invention provides a radio frequency receiving module, a method for improving its performance and communication equipment, which is helpful to improve the performance of the radio frequency receiving module. The radio frequency receiving module of the present invention includes an active module, and the input and output ends of the active module are respectively connected to one or more pre-stage filters and one or more post-stage filters, and the pre-stage filters and The post-stage filter is an acoustic filter, and at least one pre-stage filter and one post-stage filter meet one or more of the following: the number of stages of the pre-stage filter is smaller than the number of stages of the post-stage filter; The series-to-parallel average area ratio is greater than the series-to-parallel average area ratio of the post-stage filter; the matching inductance of the pre-stage filter is different from that of the post-stage filter; the out-of-band zero position of the pre-stage filter is different from that of the post-stage filter The out-of-band zeros of the filters are located differently.

Description

Radio frequency receiving module, method for improving its performance, and communication equipment

technical field

The invention relates to the technical field of communication, in particular to a radio frequency receiving module, a method for improving its performance and communication equipment.

Background technique

In recent years, the miniaturization and high-performance trend of communication equipment has accelerated, which poses higher challenges to the RF front-end. In the RF communication front end, on the one hand, miniaturization is achieved by reducing the size of the chip and package substrate, and on the other hand, better performance is achieved by reducing loss sources and better resonator matching design. In the existing filter structure, there are many passive components for matching, and at the same time, it is necessary to introduce more inductance, capacitance, coupling and other structures to improve specific performance such as roll-off insertion loss.

A typical structure of an ordinary filter is shown in FIG. 1 , which is a schematic diagram of a structure of an acoustic wave filter according to the prior art. In this filter 10, there are an input matching inductor 121, an output matching inductor 122, and a plurality of acoustic wave resonators (usually called series resonators) 101-104 between the input terminal 131 and the output terminal 132, and the connection of each series resonator Resonators 111 - 113 (usually called parallel resonators) and ground inductances 123 - 125 are respectively arranged on multiple branches (usually called parallel branches) between the point and the ground terminal. In a duplexer, for the pre-stage filter and the post-stage filter, the multiple ground inductances of the two do not have to be consistent, but the ground inductances at the same position between the two are also the same, for example, the second stage of the two The inductance to ground is the same. In addition, in the duplexer, the input matching inductance of the pre-stage filter and the post-stage filter are the same, and the output matching inductance is the same.

Fig. 2 is the schematic diagram according to the basic structure of a kind of radio frequency receiving module in the radio frequency receiving system in the prior art, wherein filter 21 and filter 22 are pre-stage filter and post-stage filter respectively, both adopt the same The chip, that is, the topology, matching method, and the internal resonator settings of the filter are consistent. Wherein the LNA is between the filter 21 and the filter 22 and is a low noise amplifier LNA, and other active modules can also be arranged here. There may be one pre-filter and post-filter as shown in the figure, or a plurality of each.

The filter 21 and the filter 22 can adopt the ladder structure shown in FIG. 1 . FIG. 1 shows a 4-3 structure, that is, 4 series resonators and 3 parallel resonators, and the number of stages is 7 (4+3=7). The functions of the filter 21 and the filter 22 are to filter out-of-band non-target frequency signals, avoid interference between signals, and ensure received signal quality. The introduction of the filter will increase the additional insertion loss, and the corresponding noise will also increase (in the filter, the insertion loss is the main source of noise), so it is guaranteed to minimize the introduction of noise while meeting the out-of-band suppression requirements. The system performance of the receiving module is of great significance.

Contents of the invention

In view of this, the present invention proposes a radio frequency receiving module, a method for improving its performance, and a communication device, which help to improve the performance of the radio frequency receiving module. The present invention provides following technical scheme:

A radio frequency receiving module, including an active module, the input and output of the active module are respectively connected to one or more pre-filters and one or more post-filters, and the pre-filter and post-filter The stage filter is an acoustic wave filter, and at least one pre-stage filter and one post-stage filter meet one or more of the following: the number of stages of the pre-stage filter is smaller than the number of stages of the post-stage filter; The series-to-parallel average area ratio is greater than the series-to-parallel average area ratio of the post-stage filter; the matched inductance of the pre-stage filter is different from that of the post-stage filter; the out-of-band zero position of the pre-stage filter is different from that of the post-stage filter The location of the out-of-band zero of the device is different.

Optionally, the active module is a low noise amplifier.

Optionally, the one front-stage filter and the one post-stage filter meet at least one of the following: different series resonant frequencies; different parallel resonant frequencies; different input matching inductances; different output matching inductances; the area of the series resonator Different; the area of the parallel resonator is different; the inductance to the ground at the same position is different; the stacked structure is different, the stacked structure is a plurality of metal layers that constitute the resonator, and the multi-layer structure such as the piezoelectric layer and the non-metallic layer is in the horizontal and vertical directions. distribution; the material properties of each laminated structure are different, and the material properties of the laminated structure include the electrical conductivity, dielectric constant and other electrical parameters of the metals, non-metals, piezoelectric materials, etc., and density, ductility, etc. of each layer of the resonator. various physical parameters.

A method for improving the performance of a radio frequency receiving module, the radio frequency receiving module includes an active module, the input and output of the active module are respectively connected to one or more pre-filters and one or more post filters stage filter, the pre-stage filter and the post-stage filter are acoustic filters, and the method includes making at least one pre-stage filter and a post-stage filter comply with one or more of the following: the number of stages of the pre-stage filter Less than the number of stages of the post-stage filter; the series-parallel average area ratio of the pre-stage filter is greater than the series-parallel average area ratio of the post-stage filter; the matching inductance of the pre-stage filter is different from that of the post-stage filter ; The out-of-band zero position of the pre-stage filter is different from the out-of-band zero position of the post-stage filter.

Optionally, the active module is a low noise amplifier.

Optionally, the one pre-stage filter and the one post-stage filter meet at least one of the following: different series resonant frequencies; different parallel resonant frequencies; different input matching inductances; different output matching inductances; different ground inductances; The area of the series resonator is different; the area of the parallel resonator is different; the ground inductance of the same position is different; the laminated structure is different; the material properties of each laminated structure are different.

A communication device includes the radio frequency receiving module of the present invention.

According to the technical solution of the present invention, there are many specific measures for the structure of the front and rear filters of the radio frequency receiving module, and various measures can be used alone or in combination, all of which help to improve the performance of the radio frequency receiving module.

Description of drawings

For purposes of illustration and not limitation, the invention will now be described according to its preferred embodiments, particularly with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram according to a structure of an acoustic wave filter in the prior art;

Fig. 2 is a schematic diagram according to the basic structure of a radio frequency receiving module in the radio frequency receiving system in the prior art;

FIG. 3A and FIG. 3B are schematic diagrams of topological structures of pre-filters according to embodiments of the present invention;

4A and 4B are schematic diagrams of echo changes according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of the effect of improving out-of-band suppression by different zero positions of the front and back stage filters according to an embodiment of the present invention.

Detailed ways

In the RF system, the noise introduced by the front stage and the rear stage contributes differently to the overall noise of the system, and the noise contribution of the front stage to the overall system noise is much greater than that of the latter stage (because the active module in the middle has attenuation to the noise of the latter stage ). In the current receiving module, the same filter is used in the front and rear stages, and the system noise is relatively poor under the condition of ensuring a certain out-of-band suppression. And using the same filter, the overall out-of-band zero point coincidence will make the specific frequency position suppress better, and most of the suppression is poor, so it is difficult to ensure the overall out-of-band suppression is better. In addition, the same filter setting has no flexible adjustment to the echo, so it is difficult to ensure better echo performance.

The embodiment of the present invention proposes that the topological structure, resonator characteristics, and matching methods of the front and rear stages be differentiated to improve the overall noise, matching performance, out-of-band suppression and other performance indicators of the radio frequency module. For example, the front and rear stages each have one filter. If the duplexer includes multiple front-stage filters and post-stage filters, then at least one front-stage filter and one post-stage filter form the above distinction.

FIG. 3A and FIG. 3B are schematic diagrams of topological structures of front-stage filters according to embodiments of the present invention, respectively. In FIG. 3A and FIG. 3B , the stages of the front-stage filter and the post-stage filter are different, wherein the stage number of the pre-stage filter is 5 stages, which is less than the stage number of the post-stage filter (9 stages). The noise factor of the cascade system is: F=F1+(F2-1)/G1+(F3-1)/G1/G2. Among them, F is the total noise factor of the system, F1-F3 are the noise factors of the pre-filter, LNA (or other active modules), and post-filter respectively, and G1 and G2 are the gains of the pre-filter and LNA. Among them, the front-stage filter does not generate gain and has insertion loss, so G1 is less than 1; while the LNA has a certain gain (G2 is much greater than 1, and the specific value of G2 is related to the gain); the noise of the post-stage filter is The system contribution is almost negligible. Therefore, when designing the filter, the insertion loss of the front-stage filter is improved (that is, the noise is reduced), but at the same time the out-of-band rejection will be deteriorated; and the insertion loss of the post-stage filter is deteriorated, but the At the same time the rejection will improve, so the noise of the system will be better while keeping the overall rejection constant. In Figure 3A, because the number of stages is small, the loss is small, so the insertion loss performance is better, that is, the introduced noise is small, but the corresponding out-of-band suppression is poor; in Figure 3B, because the number of stages is small, the loss is large, so The insertion loss is worse, so the noise introduced is larger, but the corresponding out-of-band suppression is better; the total out-of-band suppression level of the two filter cascades in Figure 3A and Figure 3B remains unchanged, but the overall noise is improved.

In the embodiment of the present invention, another measure is to set the serial-to-parallel average area ratio of the pre-filter to be greater than that of the post-filter. For the quotient A obtained by dividing the total area of all series resonators by the number of series resonators, and the quotient B obtained by dividing the total area of all parallel resonators by the number of parallel resonators, the ratio of A to B is the series here - and the average area ratio. The larger the series-to-parallel average area ratio, the better the corresponding filter insertion loss, and the worse the corresponding out-of-band rejection. Therefore, if the series-to-parallel average area ratio of the front-stage filter is larger than that of the post-stage filter, there will be better system noise, and at the same time, the deterioration of out-of-band suppression will be avoided as much as possible.

In the embodiment of the present invention, another measure is to set the input and output matching inductances of the front and rear filters to be different. In the same filter, the input and output matching inductances are the same, but the matching inductances of the front and rear filters are different. The effect is shown in FIG. 4A and FIG. 4B . FIG. 4A and FIG. 4B are schematic diagrams of echo changes according to an embodiment of the present invention, wherein FIG. 4A is S11 , and FIG. 4B is S22 . It can be seen from the figure that the input and output matching inductances of the pre- and post-stage filters are different, which helps to improve the echo.

In the embodiment of the present invention, another measure is to make the out-of-band zero points of the front and back filters different. For this purpose, the series resonant frequency Fs of the front and rear filters can be different, and the parallel resonant frequency Fp of the front and rear filters can also be different. In addition, the matching inductance or ground inductance of the front and rear filters may be different, and the areas of the series resonators or the parallel resonators of the front and rear filters may be different. One or more of the above methods can be used in combination to make the out-of-band zero points of the front and back filters different. Fig. 5 is a schematic diagram of the effect of improving out-of-band suppression by different zero positions of the front and back stage filters according to an embodiment of the present invention. The thin line in the figure is the curve of out-of-band suppression under the condition that the zero points of the front and rear filters are the same. The thick line is the curve of out-of-band suppression when the zero points of the front and rear stage filters are different. It can be seen that the above-mentioned method has a more obvious improvement on the out-of-band suppression.

The various measures listed above can be used alone, or several can be used in combination, all of which are helpful to improve the performance of the radio frequency receiving module. The radio frequency receiving module is applied to communication equipment and also helps to improve the performance of communication equipment.

The above specific implementation methods do not constitute a limitation to the protection scope of the present invention. It should be apparent to those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A radio frequency receiving module, comprising an active module, the input and output of the active module are respectively connected to one or more pre-filters and one or more post-filters, the pre-filter and the post-stage filter are acoustic wave filters, characterized in that at least one pre-stage filter and one post-stage filter meet one or more of the following: The number of stages of the pre-stage filter is smaller than the number of stages of the post-stage filter; The series-to-parallel average area ratio of the front-stage filter is greater than the series-to-parallel average area ratio of the post-stage filter; The matching inductance of the pre-filter is different from that of the post-filter; The out-of-band zero position of the pre-filter is different from the out-of-band zero position of the post-stage filter. 2. The radio frequency receiving module according to claim 1, wherein the active module is a low noise amplifier. 3. The radio frequency receiving module according to claim 1, wherein the one pre-filter and the one post-filter meet at least one of the following: The series resonant frequency is different; The parallel resonant frequency is different; The input matching inductance is different; The output matching inductance is different; The series resonators have different areas; The area of the parallel resonators is different; Different ground inductances with the same position; The layered structure is different; The material properties of each laminated structure are different. 4. A method for improving the performance of a radio frequency receiving module, the radio frequency receiving module includes an active module, the input and output of the active module are respectively connected to one or more pre-filters and one or more A post-stage filter, the pre-stage filter and the post-stage filter are acoustic wave filters, characterized in that the method includes making at least one pre-stage filter and a post-stage filter comply with one or more of the following: The number of stages of the pre-stage filter is smaller than the number of stages of the post-stage filter; The series-to-parallel average area ratio of the front-stage filter is greater than the series-to-parallel average area ratio of the post-stage filter; The matching inductance of the pre-filter is different from that of the post-filter; The out-of-band zero position of the pre-filter is different from the out-of-band zero position of the post-stage filter. 5. The method according to claim 4, wherein the active module is a low noise amplifier. 6. The method according to claim 4, wherein the one pre-filter and the one post-filter meet at least one of the following: The series resonant frequency is different; The parallel resonant frequency is different; The input matching inductance is different; The output matching inductance is different; The ground inductance is different; The series resonators have different areas; The area of the parallel resonators is different; Different ground inductances with the same position; The layered structure is different; The material properties of each laminated structure are different. 7. A communication device, characterized by comprising the radio frequency receiving module according to any one of claims 1 to 3.

Images