CN216531262U - Attenuator and attenuation circuit - Google Patents

Abstract

The utility model discloses an attenuator and an attenuation circuit, wherein the attenuator comprises an input node, an output node, a signal attenuation main circuit and a signal attenuation branch circuit; the signal attenuation main circuit is connected in series between the input node and the output node; one end of the signal attenuation branch circuit is coupled to the signal attenuation main circuit, and the other end of the signal attenuation branch circuit is grounded; the signal attenuation main circuit comprises an isolating switch and an attenuation resistor which are connected in series. The technical scheme can ensure the isolation degree between the attenuators and simultaneously improve the attenuation precision of the attenuators.

Description

Attenuator and attenuation circuit

Technical Field

The utility model relates to the technical field of radio frequency, in particular to an attenuator and an attenuation circuit.

Background

In Radio Frequency (RF) technology, a Radio Frequency front-end technology is widely applied to remote sensing devices, wireless communication devices, radar devices, portable ultrasonic devices, and the like. Among other things, attenuator circuits within certain multi-mode multi-gain stage radio frequency front end architectures typically include multi-bit attenuators to achieve different gain stages.

At present, an attenuator circuit is generally composed of a multi-bit attenuator and a plurality of switches connected in series and in parallel, so that the switches are switched according to actual conditions, and the requirements of attenuation in different degrees are met. However, in the process of attenuating a signal to be attenuated by using the conventional attenuator circuit, because a switch in the attenuator circuit still has a certain impedance in a conducting state to cause impedance mismatch, the attenuation degree is not accurate enough when the signal to be attenuated is attenuated, and the attenuated signal to be attenuated cannot meet actual requirements.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides an attenuator and an attenuation circuit, which aim to solve the problem that the attenuation degree of signals to be attenuated is not accurate enough.

An attenuator comprises an input node, an output node, a signal attenuation main circuit and a signal attenuation branch circuit;

the signal attenuation main path is connected in series between the input node and the output node;

one end of the signal attenuation branch circuit is coupled to the signal attenuation main circuit, and the other end of the signal attenuation branch circuit is grounded;

the signal attenuation main circuit comprises an isolating switch and an attenuation resistor which are connected in series.

Further, the isolation switch comprises a first isolation switch and a second isolation switch; the attenuation resistor comprises a first attenuation resistor; the signal attenuation branch comprises a first branch and a second branch;

a first end of the first isolating switch is connected with the input node, a second end of the first isolating switch is connected with a first end of the first attenuation resistor, a second end of the first attenuation resistor is connected with a first end of the second isolating switch, and a second end of the second isolating switch is connected with the output node;

one end of the first branch circuit is connected with the first end of the first isolating switch, and the other end of the first branch circuit is grounded;

one end of the second branch circuit is connected with the second end of the second isolating switch, and the other end of the second branch circuit is grounded.

Further, the first branch comprises a second attenuation resistor; the second branch includes a third attenuation resistor.

Further, the first branch further comprises a third isolating switch connected in series with the second damping resistor; the second branch further comprises a fourth isolator switch connected in series with the third damping resistor.

Further, the impedance value of the first isolation switch in the conducting state is smaller than the impedance value of the third isolation switch in the conducting state, and the impedance value of the second isolation switch in the conducting state is smaller than the impedance value of the fourth isolation switch in the conducting state.

Further, the isolation switch comprises a first isolation switch and a second isolation switch; the attenuation resistor comprises a first attenuation resistor and a second attenuation resistor; the signal attenuation branch comprises a first branch;

a first end of the first isolating switch is connected with the input node, a second end of the first isolating switch is connected with a first end of the first attenuation resistor, a second end of the first attenuation resistor is connected with a first end of the second attenuation resistor, a second end of the second attenuation resistor is connected with a first end of the second isolating switch, and a second end of the second isolating switch is connected with the output node;

one end of the first branch circuit is connected with the second end of the first attenuation resistor and the first end of the second attenuation resistor, and the other end of the first branch circuit is grounded.

Further, the isolation switch comprises a first isolation switch and a second isolation switch; the attenuation resistor comprises a first attenuation resistor and a second attenuation resistor; the signal attenuation branch comprises a first branch;

a first end of the first attenuation resistor is connected with the input node, a second end of the first attenuation resistor is connected with a first end of a first isolating switch, a second end of the first isolating switch is connected with a first end of a second isolating switch, a second end of the second isolating switch is connected with a first end of a second attenuation resistor, and a second end of the second attenuation resistor is connected with the output node;

one end of the first branch circuit is connected with the second end of the first attenuation resistor and the first end of the second attenuation resistor, and the other end of the first branch circuit is grounded.

Further, the first branch includes a third attenuation resistor.

An attenuation circuit comprises the attenuator.

Further, the attenuation circuit further comprises an input end, an output end, a first selection switch, a second selection switch and a second attenuator;

the first selection switch and the second selection switch are connected in series between the input terminal and the output terminal; the attenuator is connected in parallel with the first selection switch; the second attenuator is connected in parallel with the second selection switch.

According to the attenuator and the attenuation circuit, the attenuator comprises the input node, the output node, the signal attenuation main circuit and the signal attenuation branch circuit, the signal attenuation main circuit is connected between the input node and the output node in series, one end of the signal attenuation branch circuit is coupled to the signal attenuation main circuit, the other end of the signal attenuation branch circuit is grounded, and the signal to be attenuated is attenuated. In this embodiment, the main signal attenuation path is provided with an isolating switch and an attenuation resistor which are connected in series, when the attenuator is used for attenuating a signal to be attenuated, the isolating switch in the attenuator is controlled to be turned on, and the isolating switch and the attenuation resistor are jointly used as an attenuation element in the attenuator for attenuating the signal to be attenuated, so that the input impedance (50 Ω) and the output impedance (50 Ω) of the attenuator are matched; when the attenuator is not needed to be adopted to attenuate signals to be attenuated, the isolating switch in the attenuator is controlled to be switched off, and the isolating switch in the off state can prevent the signals to be attenuated in other attenuators in the attenuation circuit from leaking into the attenuator, so that the attenuation precision of the attenuator can be improved while the isolation degree among different attenuators in the attenuation circuit is ensured.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.

FIG. 1 is a schematic circuit diagram of an attenuator in accordance with an embodiment of the present invention;

FIG. 2 is another circuit schematic of an attenuator in an embodiment of the present invention;

FIG. 3 is another circuit schematic of an attenuator in an embodiment of the present invention;

FIG. 4 is another circuit schematic of the attenuator in an embodiment of the present invention;

FIG. 5 is another circuit schematic of the attenuator in an embodiment of the present invention;

FIG. 6 is another circuit schematic of the attenuator in an embodiment of the present invention;

FIG. 7 is a circuit diagram of an attenuation circuit according to an embodiment of the present invention.

In the figure: 11. a signal attenuation main path; 12. a signal attenuation branch; 121. a first branch; 122. a second branch circuit; 21. a first selection switch; 22. a second selection switch; 31. a first attenuator; 32. a second attenuator.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the utility model to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity to indicate like elements throughout.

It will be understood that when an element or layer is referred to as being "on" …, "adjacent to …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …," "directly adjacent to …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial relational terms such as "under …," "under …," "below," "under …," "over …," "above," and the like may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below …" and "below …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the utility model, however, the utility model is capable of other embodiments in addition to those detailed.

The present embodiment provides an attenuator, as shown in fig. 2 below, including an input node Rin, an output node Rout, a signal attenuation main path 11, and a signal attenuation branch path 12; the signal attenuation main circuit 11 is connected in series between the input node Rin and the output node Rout; one end of the signal attenuation branch 12 is coupled to the signal attenuation main circuit 11, and the other end of the signal attenuation branch 12 is grounded; the signal attenuation main circuit 11 includes a series connection of an isolator and an attenuation resistor.

The input node Rin is a node to which a signal to be attenuated is input. The output node Rout is a node that outputs the attenuated signal. The signal attenuation main circuit 11 is a circuit configured to attenuate a signal to be attenuated in the attenuator, and is disposed between the input node Rin and the output node Rout. The signal attenuation branch 12 refers to another circuit configured to attenuate a signal to be attenuated in the attenuator, and is provided between the signal attenuation main circuit 11 and the ground terminal.

In a specific embodiment, as shown in fig. 1, the attenuator is applied in an attenuation circuit for performing signal attenuation with a certain attenuation amount on a signal to be attenuated according to actual conditions. Optionally, the attenuation circuit comprises a plurality of selection switches and a plurality of attenuators of different attenuation levels. Illustratively, the plurality of attenuators of different attenuation levels includes a 1dB attenuator, a 3dB attenuator, and a 6dB attenuator. As an example, the plurality of selection switches are connected in series between the input node Rin of the attenuation circuit and the output node Rout of the attenuation circuit, the plurality of attenuators with different attenuation degrees are respectively connected in parallel to each selection switch, the selection switches can be switched according to actual requirements, and the attenuators with different attenuation degrees are selected to attenuate signals to be attenuated. For example, a 1dB attenuator may be selected to attenuate a signal to be attenuated, or a 3dB attenuator may be selected to attenuate the signal to be attenuated, or a 6dB attenuator may be selected to attenuate the signal to be attenuated, or a 1dB attenuator and a 3dB attenuator may be selected to attenuate the signal to be attenuated together, or a 3dB attenuator and a 6dB attenuator may be selected to attenuate the signal to be attenuated together, or a 1dB attenuator, a 3dB attenuator and a 6dB attenuator may be selected to attenuate the signal to be attenuated together.

In the related art, as shown in fig. 1, when a single attenuator is selected to attenuate a signal to be attenuated, for example, only a 1dB attenuator is selected to attenuate the signal to be attenuated, in order to prevent signal leakage, an isolation switch (e.g., S5/S6/S7/S8/S9/S10 in fig. 1) is connected in series with an input node Rin and an output node Rout of each attenuator, when the 1dB attenuator is selected to attenuate the signal to be attenuated, the isolation switch S5, the isolation switch S6, the selection switch S3 and the selection switch S4 are closed, and the isolation switch S7, the isolation switch S8, the isolation switch S9, the isolation switch S10, the selection switch S1 and the selection switch S2 are opened, so as to prevent the signal to be attenuated passing through the 1dB attenuator from leaking to other paths (e.g., the path of the 3dB attenuator and the path of the 6dB attenuator), thereby improving the isolation between the attenuators. However, when two cascaded attenuators are required to jointly attenuate the signal to be attenuated, for example: when the signal attenuation of 4dB needs to be carried out on the signal to be attenuated, the 1dB attenuator and the 3dB attenuator need to be selected simultaneously to jointly attenuate the signal to be attenuated, namely the isolating switch S5, the isolating switch S6, the isolating switch S7, the isolating switch S8 and the selecting switch S4 need to be closed, and the isolating switch S9, the isolating switch S10, the selecting switch S1, the selecting switch S2 and the selecting switch S3 need to be opened.

In order to solve the above problem, as shown in fig. 2, the attenuator in the present embodiment includes a signal attenuation main path 11 and a signal attenuation branch path 12. In a specific embodiment, the signal attenuation main circuit 11 is connected in series between the input node Rin and the output node Rout, one end of the signal attenuation branch circuit 12 is coupled to the signal attenuation main circuit 11, and the other end of the signal attenuation branch circuit 12 is grounded, so as to form an attenuation network for attenuating the signal to be attenuated. The attenuation network may be, for example, a Π -type attenuation network or a T-type attenuation network.

The signal attenuation main circuit 11 of the attenuator comprises an isolation switch and an attenuation resistor which are connected in series, and the attenuation value presented by the attenuator is determined by the resistance value of the attenuation resistor and the impedance value of the isolation switch in the conducting state. When the attenuator is used for attenuating a signal to be attenuated, an isolating switch in the attenuator is controlled to be conducted, and the isolating switch and the attenuation resistor are jointly used as an attenuation element in the attenuator for attenuating the signal to be attenuated, so that the input impedance (50 omega) and the output impedance (50 omega) of the attenuator are matched; when the attenuator is not needed to be adopted to attenuate signals to be attenuated, the isolating switch in the attenuator is controlled to be switched off, and the isolating switch in the off state can prevent the signals to be attenuated in other attenuators in the attenuation circuit from leaking into the attenuator, so that the attenuation precision of the attenuator can be improved while the isolation degree among different attenuators in the attenuation circuit is ensured.

In this embodiment, the attenuator includes an input node Rin, an output node Rout, a signal attenuation main circuit 11 and a signal attenuation branch circuit 12, and the signal attenuation main circuit 11 is connected in series between the input node Rin and the output node Rout, and one end of the signal attenuation branch circuit 12 is coupled to the signal attenuation main circuit 11, and the other end of the signal attenuation branch circuit 12 is grounded, so that the signal to be attenuated is attenuated. In the embodiment, the signal attenuation main circuit 11 is provided with the isolating switch and the attenuation resistor which are connected in series, when the attenuator is used for attenuating a signal to be attenuated, the isolating switch in the attenuator is controlled to be turned on, and the isolating switch and the attenuation resistor are jointly used as attenuation elements in the attenuator for attenuating the signal to be attenuated, so that the input impedance (50 Ω) and the output impedance (50 Ω) of the attenuator are matched; when the attenuator is not needed to be adopted to attenuate signals to be attenuated, the isolating switch in the attenuator is controlled to be switched off, and the isolating switch in the off state can prevent the signals to be attenuated in other attenuators in the attenuation circuit from leaking into the attenuator, so that the attenuation precision of the attenuator can be improved while the isolation degree among different attenuators in the attenuation circuit is ensured.

In one embodiment, as shown in fig. 3, the isolation switch includes a first isolation switch S111 and a second isolation switch S112; the attenuation resistor comprises a first attenuation resistor R111; the signal attenuation branch 12 includes a first branch 121 and a second branch 122; a first end of the first isolating switch S111 is connected to the input node Rin, a second end of the first isolating switch S111 is connected to a first end of the first attenuation resistor R111, a second end of the first attenuation resistor R111 is connected to a first end of the second isolating switch S112, and a second end of the second isolating switch S112 is connected to the output node Rout; one end of the first branch 121 is connected to the first end of the first isolation switch S111, and the other end of the first branch 121 is grounded; one end of the second branch 122 is connected to the second end of the second isolation switch S112, and the other end of the second branch 122 is grounded.

In an embodiment, the main signal attenuation circuit 11 and the branch signal attenuation circuit 12 form a Π -type attenuation network, and the input impedance of the Π -type attenuation network is 50 Ω, and the output impedance of the Π -type attenuation network is 50 Ω. Illustratively, the isolation switches include a first isolation switch S111 and a second isolation switch S112; the attenuation resistor comprises a first attenuation resistor R111; the signal attenuation branch 12 includes a first branch 121 and a second branch 122. In the present embodiment, the first end of the first isolation switch S111 is connected to the input node Rin, the second end of the first isolation switch S111 is connected to the first end of the first attenuation resistor R111, the second end of the first attenuation resistor R111 is connected to the first end of the second isolation switch S112, the second end of the second isolation switch S112 is connected to the output node Rout, one end of the first branch 121 is connected to the first end of the first isolation switch S111, and the other end of the first branch 121 is grounded; one end of the second branch 122 is connected to the second end of the second isolating switch S112, and the other end of the second branch 122 is grounded, so as to form an n-type attenuation network. It should be noted that, in this embodiment, when the first isolation switch S111 and the second isolation switch S112 are turned on, the first isolation switch S111, the second isolation switch S112 and the first attenuation resistor R111 are used together as an attenuation element in an attenuator to attenuate a signal to be attenuated, that is, an attenuation value of the attenuator at this time is related to a resistance value of the first attenuation resistor R111, an impedance value of the first isolation switch S111 in a turned-on state and an impedance value of the second isolation switch S112 in a turned-on state; so that the input impedance and the output impedance of the attenuator are both matched with the impedance of 50 omega. When the first isolating switch S111 and the second isolating switch S112 are turned off, the first isolating switch S111 and the second isolating switch S112 can prevent signals in other attenuators in the attenuation circuit from leaking into the attenuators, so that the attenuation precision of the attenuators is improved while the isolation degree between different attenuators is ensured.

In one embodiment, as shown in fig. 3, the first branch 121 includes a second attenuation resistor R112; the second branch 122 includes a third attenuation resistor R113.

In this embodiment, the first branch 121 includes a second attenuation resistor R112, the second branch 122 includes a third attenuation resistor R113, the second attenuation resistor R112 and the third attenuation resistor R113, together with the first isolation switch S111, the second isolation switch S112 and the first attenuation resistor R111 in the above-mentioned embodiment, form a Π -type attenuation network, when the attenuator attenuates the signal to be attenuated, the first isolating switch S111 and the second isolating switch S112 are turned on, the first isolating switch S111, the second isolating switch S112, the first attenuating resistor R111, the second attenuating resistor R112 and the third attenuating resistor R113 are used as attenuating elements in the attenuator to attenuate the signal to be attenuated, namely, the attenuation value of the attenuator is related to the resistance value of the first attenuation resistor R111, the resistance value of the second attenuation resistor R112, the resistance value of the third attenuation resistor R113, the impedance value of the first isolating switch S111 in the conducting state and the impedance value of the second isolating switch S112 in the conducting state; when the attenuator does not work, the first isolating switch S111 and the second isolating switch S112 are switched off to prevent signals in other attenuators in the attenuation circuit from leaking into the attenuator, so that the attenuation precision of the attenuator is improved while the isolation degree between different attenuators is ensured.

In one embodiment, as shown in fig. 4, the first branch 121 further includes a third isolation switch S113 connected in series with the second damping resistor R112; the second branch 122 further comprises a fourth isolating switch S114 connected in series with the third damping resistor R113.

In this embodiment, the first branch 121 further includes a third isolation switch S113 connected in series with the second attenuation resistor R112, and the second branch 122 further includes a fourth isolation switch S114 connected in series with the third attenuation resistor R113. The present embodiment avoids the effect of the correlation between the resistances in the signal attenuation branches 12 of the two cascaded attenuators by providing a third isolation switch S113 in the first branch 121, which is connected in series with the second attenuation resistor R112, and a fourth isolation switch S114 in the second branch 122, which is connected in series with the third attenuation resistor R113. For example: when the 1dB attenuator is used to attenuate a signal to be attenuated, if the fourth isolator S114 connected in series with the third attenuator R113 is not connected to the second branch 122 of the 1dB attenuator, and the third isolator S113 connected in series with the second attenuator R112 is not connected to the first branch 121 of the 3dB attenuator, when the 1dB attenuator is used to attenuate a signal to be attenuated, the second attenuator R112 in the first branch 121 of the 3dB attenuator is connected in parallel with the third attenuator R113 in the second branch 122 of the 1dB attenuator, thereby affecting the attenuation accuracy of the 1dB attenuator.

In one embodiment, the formula is designed according to the parameters of the n-type attenuation network, and in this embodiment,

wherein LOSS [ indB ]]Is the attenuation of the attenuator, R_S111+R111+R_S112The total resistance value R is the sum of the resistance value of the first isolation switch S111 in the conducting state, the resistance value of the second isolation switch S112 in the conducting state and the first attenuation resistor R111_S113+ R112 is the total impedance value of the sum of the impedance values of the second damping resistor R112 and the third isolating switch S113 in the conducting state, R_S114The + R113 is a resistance value obtained by adding the third damping resistor R113 to the resistance value of the fourth isolation switch S114 in the on state.

In a practical application, since the isolation switch in the attenuator circuit is a non-ideal switch, the isolation switch in the attenuator circuit still has a certain impedance in the conducting state to cause the input and output impedance to deviate from the target impedance (for example, 50 ohms), so that the actual attenuation deviates from the total attenuation ideally added by the multi-bit attenuators when the multi-bit attenuators are cascaded. Therefore, in this embodiment, the circuit structure of the attenuator is improved, and the isolation switches originally arranged at two ends of the attenuator are used as a part of the circuit structure of the attenuator, and the isolation switches and the attenuation resistors in this embodiment are used together as attenuation elements in the attenuator to attenuate signals to be attenuated, so that the actual attenuation amount when the multi-bit attenuators are cascaded is equal to the total attenuation amount ideally added by the multi-bit attenuators, and the attenuation accuracy when the multi-bit attenuators are cascaded can be improved while the isolation degree between the multi-bit cascaded attenuators in the attenuation circuit is ensured.

In one embodiment, the impedance value of the first isolation switch S111 in the conducting state is smaller than the impedance value of the third isolation switch S113 in the conducting state, and the impedance value of the second isolation switch S112 in the conducting state is smaller than the impedance value of the fourth isolation switch S114 in the conducting state.

In this embodiment, in order to keep the balance of the pi attenuation network, it is preferable that the impedance value of the third isolation switch S113 in the on state is equal to the impedance value of the fourth isolation switch S114 in the on state, and the impedance value of the first isolation switch S111 in the on state is equal to the impedance value of the second isolation switch S112 in the on state. In addition, in the pi-type attenuation network, in order to prevent most of the signal to be attenuated passing through the attenuator from passing through the signal attenuation branch 12 to the ground, the resistance values of the second attenuation resistor R112 and the third attenuation resistor R113 in the signal attenuation branch 12 are much larger than the resistance value of the first attenuation resistor R111 in the signal attenuation main circuit 11. In the present application, a third isolation switch S113 connected in series with the second attenuation resistor R112 is connected to the first branch 121; and a fourth isolating switch S114 connected in series with the third attenuation resistor R113 is connected in the second branch 122, and by configuring that the impedance value of the first isolating switch S111 in the conducting state is smaller than that of the third isolating switch S113 in the conducting state, and the impedance value of the second isolating switch S112 in the conducting state is smaller than that of the fourth isolating switch S114 in the conducting state, the related influence between the resistances on the signal attenuation branches 12 of the two cascaded attenuators is avoided. For example: when the 1dB attenuator is used to attenuate a signal to be attenuated, if the fourth isolator S114 connected in series with the third attenuator R113 is not connected to the second branch 122 of the 1dB attenuator, and the third isolator S113 connected in series with the second attenuator R112 is not connected to the first branch 121 of the 3dB attenuator, when the 1dB attenuator is used to attenuate a signal to be attenuated, the second attenuator R112 in the first branch 121 of the 3dB attenuator is connected in parallel with the third attenuator R113 in the second branch 122 of the 1dB attenuator, thereby affecting the attenuation accuracy of the 1dB attenuator.

In one embodiment, as shown in fig. 5, the isolation switch includes a first isolation switch S111 and a second isolation switch S112; the attenuation resistor comprises a first attenuation resistor R111 and a second attenuation resistor R112; the signal attenuation branch 12 includes a first branch 121; a first end of the first isolating switch S111 is connected to the input node Rin, a second end of the first isolating switch S111 is connected to a first end of the first attenuation resistor R111, a second end of the first attenuation resistor R111 is connected to a first end of the second attenuation resistor R112, a second end of the second attenuation resistor R112 is connected to a first end of the second isolating switch S112, and a second end of the second isolating switch S112 is connected to the output node Rout; one end of the first branch 121 is connected to the second end of the first attenuation resistor R111 and the first end of the second attenuation resistor R112, and the other end of the first branch 121 is grounded.

In this embodiment, the signal attenuation main circuit 11 and the signal attenuation branch circuit 12 form a T-type attenuation network, and the input impedance of the T-type attenuation network is 50 Ω, and the output impedance of the T-type attenuation network is 50 Ω. Illustratively, the isolation switches include a first isolation switch S111 and a second isolation switch S112; the attenuation resistor comprises a first attenuation resistor R111 and a second attenuation resistor R112; the signal attenuation branch 12 includes a first branch 121. In the present embodiment, the first terminal of the first isolation switch S111 is connected to the input node Rin, the second terminal of the first isolation switch S111 is connected to the first terminal of the first attenuation resistor R111, the second terminal of the first attenuation resistor R111 is connected to the first terminal of the second attenuation resistor R112, the second terminal of the second attenuation resistor R112 is connected to the first terminal of the second isolation switch S112, and the second terminal of the second isolation switch S112 is connected to the output node Rout; one end of the first branch 121 is connected to the second end of the first attenuation resistor R111 and the first end of the second attenuation resistor R112, and the other end of the first branch 121 is grounded, thereby forming a T-shaped attenuation network.

In this embodiment, when the first isolation switch S111 and the second isolation switch S112 are turned on, the first isolation switch S111, the second isolation switch S112, the first attenuation resistor R111, and the second attenuation resistor R112 collectively serve as an attenuation element of an attenuator to attenuate a signal to be attenuated, so that the input impedance (50 Ω) and the output impedance (50 Ω) of the attenuator are matched. When the first isolating switch S111 and the second isolating switch S112 are turned off, the first isolating switch S111 and the second isolating switch S112 in the turned-off state can prevent the signal to be attenuated in other attenuators in the attenuation circuit from leaking into the attenuator, so that the attenuation accuracy of the attenuator can be improved while the isolation between different attenuators in the attenuation circuit is ensured.

In one embodiment, as shown in fig. 6, the isolation switch includes a first isolation switch S111 and a second isolation switch S112; the attenuation resistor comprises a first attenuation resistor R111 and a second attenuation resistor R112; the signal attenuation branch 12 includes a first branch 121; a first end of the first attenuation resistor R111 is connected to the input node Rin, a second end of the first attenuation resistor R111 is connected to a first end of the first isolation switch S111, a second end of the first isolation switch S111 is connected to a first end of the second isolation switch S112, a second end of the second isolation switch S112 is connected to a first end of the second attenuation resistor R112, and a second end of the second attenuation resistor R112 is connected to the output node Rout; one end of the first branch 121 is connected to the second end of the first attenuation resistor R111 and the first end of the second attenuation resistor R112, and the other end of the first branch 121 is grounded.

In this embodiment, the signal attenuation main circuit 11 and the signal attenuation branch circuit 12 form a T-type attenuation network, and the input impedance of the T-type attenuation network is 50 Ω, and the output impedance of the T-type attenuation network is 50 Ω. Illustratively, the isolation switches include a first isolation switch S111 and a second isolation switch S112; the attenuation resistor comprises a first attenuation resistor R111 and a second attenuation resistor R112; the signal attenuation branch 12 includes a first branch 121. In the present embodiment, the first terminal of the first attenuation resistor R111 is connected to the input node Rin, the second terminal of the first attenuation resistor R111 is connected to the first terminal of the first isolation switch S111, the second terminal of the first isolation switch S111 is connected to the first terminal of the second isolation switch S112, the second terminal of the second isolation switch S112 is connected to the first terminal of the second attenuation resistor R112, and the second terminal of the second attenuation resistor R112 is connected to the output node Rout; one end of the first branch 121 is connected to the second end of the first attenuation resistor R111 and the first end of the second attenuation resistor R112, and the other end of the first branch 121 is grounded, thereby forming a T-shaped attenuation network.

In this embodiment, when the first isolation switch S111 and the second isolation switch S112 are turned on, the first isolation switch S111, the second isolation switch S112, the first attenuation resistor R111, and the second attenuation resistor R112 collectively serve as an attenuation element of an attenuator to attenuate a signal to be attenuated, so that the input impedance (50 Ω) and the output impedance (50 Ω) of the attenuator are matched. When the first isolating switch S111 and the second isolating switch S112 are turned off, the first isolating switch S111 and the second isolating switch S112 in the off state can prevent the signal to be attenuated in other attenuators in the attenuator circuit from leaking into the attenuator, so that the isolation degree between different attenuators in the attenuator circuit is ensured, and the attenuation accuracy of the attenuator can be improved.

In one embodiment, as shown in fig. 5, the first branch 121 includes a third attenuation resistor R113.

In this embodiment, when the first isolation switch S111 and the second isolation switch S112 are turned on, the first isolation switch S111, the second isolation switch S112, the first attenuation resistor R111, the second attenuation resistor R112, and the third attenuation resistor R113 collectively serve as an attenuation element of the attenuator to attenuate a signal to be attenuated, so that the input impedance (50 Ω) and the output impedance (50 Ω) of the attenuator are matched. When the first isolating switch S111 and the second isolating switch S112 are turned off, the first isolating switch S111 and the second isolating switch S112 in the turned-off state can prevent the signal to be attenuated in other attenuators in the attenuation circuit from leaking into the attenuator, so that the attenuation accuracy of the attenuator can be improved while the isolation between different attenuators in the attenuation circuit is ensured.

In one embodiment, the formula is designed according to the parameters of the T-shaped attenuation network, and in this embodiment,

wherein S113 is the resistance value of the third attenuation resistor R113, R_S111+ R111 is the total impedance value of the first switch S111 in the conducting state and the first damping resistor R111, R_S112The + R112 refers to a total resistance value of the impedance value of the second isolation switch S112 in the on state added to the second attenuation resistor R112.

In a practical application, since the isolation switch in the attenuator circuit is a non-ideal switch, the isolation switch in the attenuator circuit still has a certain impedance in the conducting state to cause the input and output impedance to deviate from the target impedance (for example, 50 ohms), so that the actual attenuation deviates from the total attenuation ideally added by the multi-bit attenuators when the multi-bit attenuators are cascaded. Therefore, in this embodiment, the circuit structure of the attenuator is improved, and the isolation switches originally arranged at two ends of the attenuator are used as a part of the circuit structure of the attenuator, and the isolation switches and the attenuation resistors in this embodiment are used together as attenuation elements in the attenuator to attenuate signals to be attenuated, so that the actual attenuation amount when the multi-bit attenuators are cascaded is equal to the total attenuation amount ideally added by the multi-bit attenuators, and the attenuation accuracy when the multi-bit attenuators are cascaded can be improved while the isolation degree between the multi-bit cascaded attenuators in the attenuation circuit is ensured.

The present embodiment provides an attenuation circuit, which is characterized by comprising the above attenuator.

In one embodiment, as shown in fig. 7, the attenuation circuit further includes an input terminal, an output terminal, a first selection switch 21, a second selection switch 22, and a second attenuator 32; the first selection switch 21 and the second selection switch 22 are connected in series between the input terminal and the output terminal; the first attenuator 31 is connected in parallel with the first selection switch 21; the second attenuator 32 is connected in parallel with the second selection switch 22.

In this embodiment, the attenuation circuit further includes an input terminal, an output terminal, a first selection switch 21, a second selection switch 22, and a second attenuator 32; the first selection switch 21 and the second selection switch 22 are connected in series between the input terminal and the output terminal; the first attenuator 31 is connected in parallel with the first selection switch 21; the second attenuator 32 is connected in parallel with the second selection switch 22. When the first attenuator 31 is operated and the second attenuator 32 is not operated, the first selection switch 21 is turned off and the second selection switch 22 is turned on. When the first attenuator 31 is not operated and the second attenuator 32 is operated, the first selection switch 21 is turned on and the second selection switch 22 is turned off. When both the first attenuator 31 and the second attenuator 32 are operated, the first selection switch 21 is turned on and the second selection switch 22 is turned on.

The second attenuator 32 in the present embodiment may be a conventional attenuator or an attenuator in the above-described embodiment. The attenuator in the above embodiment is preferable.

In this embodiment, the circuit structure of the first attenuator 31 and/or the second attenuator 32 is improved, and the isolation switches originally arranged at two ends of the first attenuator 31 and/or the second attenuator 32 are used as a part of the circuit structure of the first attenuator 31 and/or the second attenuator 32, and the isolation switches and the attenuation resistors in this embodiment are used together as attenuation elements in the attenuator to attenuate a signal to be attenuated, so that the actual attenuation amount when the first attenuator 31 and the second attenuator 32 are cascaded is equal to the total attenuation amount ideally added by the first attenuator 31 and the second attenuator 32, and the attenuation accuracy when the first attenuator 31 and the second attenuator 32 are cascaded in the attenuation circuit is improved while the isolation degree between the first attenuator 31 and the second attenuator 32 is ensured.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims (10)

1. An attenuator is characterized by comprising an input node, an output node, a signal attenuation main circuit and a signal attenuation branch circuit;

the signal attenuation main path is connected in series between the input node and the output node;

one end of the signal attenuation branch circuit is coupled to the signal attenuation main circuit, and the other end of the signal attenuation branch circuit is grounded;

the signal attenuation main circuit comprises an isolating switch and an attenuation resistor which are connected in series.

2. The attenuator of claim 1, wherein the isolation switch comprises a first isolation switch and a second isolation switch; the attenuation resistor comprises a first attenuation resistor; the signal attenuation branch comprises a first branch and a second branch;

a first end of the first isolating switch is connected with the input node, a second end of the first isolating switch is connected with a first end of the first attenuation resistor, a second end of the first attenuation resistor is connected with a first end of the second isolating switch, and a second end of the second isolating switch is connected with the output node;

one end of the first branch circuit is connected with the first end of the first isolating switch, and the other end of the first branch circuit is grounded;

one end of the second branch circuit is connected with the second end of the second isolating switch, and the other end of the second branch circuit is grounded.

3. The attenuator of claim 2, wherein the first branch includes a second attenuation resistor; the second branch includes a third attenuation resistor.

4. The attenuator of claim 3, wherein the first branch further comprises a third isolation switch connected in series with the second attenuation resistor; the second branch further comprises a fourth isolator switch connected in series with the third damping resistor.

5. The attenuator of claim 4, wherein the impedance value of the first isolator switch in the on state is less than the impedance value of the third isolator switch in the on state, and the impedance value of the second isolator switch in the on state is less than the impedance value of the fourth isolator switch in the on state.

6. The attenuator of claim 1, wherein the isolation switch comprises a first isolation switch and a second isolation switch; the attenuation resistor comprises a first attenuation resistor and a second attenuation resistor; the signal attenuation branch comprises a first branch;

a first end of the first isolating switch is connected with the input node, a second end of the first isolating switch is connected with a first end of the first attenuation resistor, a second end of the first attenuation resistor is connected with a first end of the second attenuation resistor, a second end of the second attenuation resistor is connected with a first end of the second isolating switch, and a second end of the second isolating switch is connected with the output node;

one end of the first branch circuit is connected with the second end of the first attenuation resistor and the first end of the second attenuation resistor, and the other end of the first branch circuit is grounded.

7. The attenuator of claim 1, wherein the isolation switch comprises a first isolation switch and a second isolation switch; the attenuation resistor comprises a first attenuation resistor and a second attenuation resistor; the signal attenuation branch comprises a first branch;

a first end of the first attenuation resistor is connected with the input node, a second end of the first attenuation resistor is connected with a first end of a first isolating switch, a second end of the first isolating switch is connected with a first end of a second isolating switch, a second end of the second isolating switch is connected with a first end of a second attenuation resistor, and a second end of the second attenuation resistor is connected with the output node;

one end of the first branch circuit is connected with the second end of the first attenuation resistor and the first end of the second attenuation resistor, and the other end of the first branch circuit is grounded.

8. The attenuator of claim 6 or 7, wherein the first branch includes a third attenuation resistor.

9. An attenuation circuit comprising the attenuator of any one of claims 1 to 8.

10. The attenuation circuit of claim 9, further comprising an input, an output, a first selection switch, a second selection switch, and a second attenuator;

the first selection switch and the second selection switch are connected in series between the input terminal and the output terminal; the attenuator is connected in parallel with the first selection switch; the second attenuator is connected in parallel with the second selection switch.

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