Digital attenuator and digital attenuation system

Abstract

The application provides a digital attenuator and a digital attenuation system. The digital attenuator comprises a plurality of attenuation units with different target attenuation values connected in series. Any attenuation unit comprises a conduction control module and an attenuation module connected in parallel. The attenuation module comprises a π-type attenuator and a switching device connected in series. When the conduction control module is turned on, the π-type attenuator in the attenuation module is disabled. When the conduction control module is turned off and the switching device in the attenuation module is closed, the π-type attenuator is enabled.

Description

Technical Field

[0001] This application relates to the field of radio frequency signal processing technology, and more specifically, to a digitally controlled attenuator and a digitally controlled attenuation system. Background Technology

[0002] Existing numerically controlled attenuators mostly employ cascaded schemes based on switching-type Pi attenuation structures, which only offer good attenuation accuracy within narrow bandwidths. When applied to ultra-wideband scenarios, limitations such as the structure's inherently weak frequency response and deteriorated impedance matching lead to significant deviations between the attenuation at different frequencies and the target value. Ultimately, this results in a decrease in overall attenuation accuracy, failing to meet the system requirements for high-precision, wideband attenuation control. Utility Model Content

[0003] The main objective of this application is to provide a digitally controlled attenuator and a digitally controlled attenuation system to at least solve the problem of low attenuation accuracy of digitally controlled attenuators in ultra-wideband applications in the prior art.

[0004] To achieve the above objectives, according to one aspect of this application, a numerically controlled attenuator is provided, comprising: a plurality of attenuation units with different target attenuation values ​​connected in series, each of the attenuation units comprising a conduction control module and an attenuation module connected in parallel, the attenuation module comprising an electrically connected π-type attenuator and a switching device; wherein, when the conduction control module is turned on, the π-type attenuator in the attenuation module is disabled, and when the conduction control module is turned off and the switching device in the attenuation module is closed, the π-type attenuator is effective.

[0005] Optionally, one of the multiple attenuation units with different target attenuation values ​​connected in series is a first attenuation unit. The first attenuation unit includes a first conduction control module and a first attenuation module. The first attenuation module includes a first π-type attenuator, a first switching device, a second switching device, a first voltage divider, and a second voltage divider. The first terminal of the first switching device is connected to the first terminal of the first conduction control module, serving as the first terminal of the first attenuation unit. The second terminal of the first switching device is electrically connected to the first terminal of the first voltage divider. The second terminal of the first voltage divider is electrically connected to the first terminal of the first π-type attenuator. The second terminal of the first π-type attenuator is electrically connected to the first terminal of the second voltage divider. The second terminal of the second voltage divider is electrically connected to the first terminal of the second switching device. The second terminal of the second switching device and the second terminal of the first conduction control module serve as the second terminal of the first attenuation unit.

[0006] Optionally, the first conduction control module includes: a third switching device, a first energy storage device, and a fourth switching device; wherein, the first end of the third switching device is the first end of the first conduction control module, the second end of the third switching device is electrically connected to the first end of the first energy storage device, the first end of the fourth switching device is electrically connected to the second end of the first energy storage device, and the second end of the fourth switching device is the second end of the first conduction control module.

[0007] Optionally, the first voltage divider and the second voltage divider have the same resistance.

[0008] Optionally, the first voltage divider device includes multiple resistors connected in parallel or in series.

[0009] Optionally, one of the multiple series-connected attenuation units with different target attenuation values ​​is a second attenuation unit. The second attenuation unit includes a second conduction control module and a second attenuation module. The second attenuation module includes a second π-type attenuator, a fifth switching device, a sixth switching device, a second energy storage device, and a third energy storage device. The first terminal of the fifth switching device serves as the first terminal of the second attenuation module, the second terminal of the fifth switching device is electrically connected to the first terminal of the second π-type attenuator, the second terminal of the second π-type attenuator is electrically connected to the first terminal of the sixth switching device, the second terminal of the sixth switching device serves as the second terminal of the second attenuation module, the first terminal of the second energy storage device is electrically connected to the first terminal of the second π-type attenuator, the first terminal of the third energy storage device is electrically connected to the second terminal of the second π-type attenuator, and the second terminal of the second energy storage device, the second terminal of the third energy storage device, the third terminal of the second π-type attenuator, and the fourth terminal of the second π-type attenuator are all grounded.

[0010] Optionally, the second energy storage device and the third energy storage device have the same capacitance value.

[0011] Optionally, the third energy storage device is a capacitor.

[0012] Optionally, the switching device is one of the following: CMOS, PIN diode, and MEMS.

[0013] According to another aspect of this application, a numerically controlled attenuation system is provided, comprising: any of the numerically controlled attenuators described above.

[0014] By applying the technical solution of this application, a parallel structure of the conduction control module and the attenuation module is set. When the conduction control module is turned on, the signal bypasses the π-type attenuator. When the conduction control module is turned off and the switching device in the attenuation module is turned on, the signal enters the π-type attenuator and achieves the set attenuation value. This realizes on-demand conduction control of each weighted attenuation unit. By using a bypass path instead of directly disconnecting or inserting the attenuation device, the reflections introduced by the switching in the signal path are significantly reduced, which helps to buffer impedance changes. This makes the frequency response more stable, the amplitude response closer to the target attenuation value, improves bandwidth consistency, and thus improves attenuation accuracy. This solves the problem of low attenuation accuracy of CNC attenuators in ultra-wideband applications. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0016] Figure 1 A schematic diagram of a numerically controlled attenuator provided according to an embodiment of this application is shown;

[0017] Figure 2 A schematic diagram of a first attenuation unit provided according to an embodiment of this application is shown;

[0018] Figure 3 A schematic diagram of a second attenuation unit provided according to an embodiment of this application is shown.

[0019] The above figures include the following reference numerals:

[0020] 12. Attenuation unit; 14. First conduction control module; 16. First attenuation module; 18. First π-type attenuator; 20. Second conduction control module; 22. Second attenuation module; 24. Second π-type attenuator. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises 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 such processes, methods, products, or apparatus.

[0024] As described in the background section, existing digitally controlled attenuators suffer from low attenuation accuracy in ultra-wideband applications. To address these technical issues, embodiments of this application provide a digitally controlled attenuator and a digitally controlled attenuation system.

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0026] An embodiment of this application provides a digitally controlled attenuator. Figure 1 A schematic diagram of a numerically controlled attenuator of this application is shown as an example, such as... Figure 1 As shown, the above-mentioned numerically controlled attenuator includes:

[0027] Multiple attenuation units 12 with different target attenuation values ​​connected in series, each of the attenuation units 12 includes a conduction control module and an attenuation module connected in parallel, and the attenuation module includes an electrically connected π-type attenuator and a switching device.

[0028] Specifically, when the aforementioned conduction control module is on, the aforementioned π-type attenuator in the aforementioned attenuation module is ineffective; when the aforementioned conduction control module is off and the aforementioned switching device in the aforementioned attenuation module is closed, the aforementioned π-type attenuator is effective.

[0029] In the above embodiments, by setting a parallel structure between the conduction control module and the attenuation module, when the conduction control module is turned on, the signal bypasses the π-type attenuator. When the conduction control module is turned off and the switching device in the attenuation module is turned on, the signal enters the π-type attenuator and achieves the set attenuation value. This realizes on-demand conduction control of each bit weight attenuation unit. By using a bypass path instead of directly disconnecting or adding attenuation devices, the reflections introduced by switching in the signal path are reduced, which helps to buffer impedance changes. This makes the frequency response more stable, the amplitude response closer to the target attenuation value, improves bandwidth consistency, and thus improves attenuation accuracy. This solves the problem of low attenuation accuracy of CNC attenuators in ultra-wideband applications.

[0030] Specifically, when the "conduction control module" is turned on, the signal bypasses the π-type attenuator, which is equivalent to bypassing the attenuation bit; when the "conduction control module" is turned off and the "switching device in the attenuation module" is turned on, the signal enters the π-type attenuator and achieves the set attenuation value, that is, the attenuation bit is enabled.

[0031] In one alternative, such as Figure 2 As shown, one of the above-mentioned attenuation units with different target attenuation values ​​connected in series is a first attenuation unit. The first attenuation unit includes a first conduction control module 14 and a first attenuation module 16. The first attenuation module 16 includes a first π-type attenuator 18, a first switching device S1, a second switching device S2, a first voltage divider device R1, and a second voltage divider device R2. The first end of the first switching device S1 and the first end of the first conduction control module 14 serve as the first end of the first attenuation unit. The second end of the first switching device S1 is electrically connected to the first end of the first voltage divider device R1. The second end of the first voltage divider device R1 is electrically connected to the first end of the first π-type attenuator 18. The second end of the first π-type attenuator 18 is electrically connected to the first end of the second voltage divider device R2. The second end of the second voltage divider device R2 is electrically connected to the first end of the second switching device S2. The second end of the second switching device S2 and the second end of the first conduction control module 14 serve as the second end of the first attenuation unit.

[0032] In the above embodiments, since any sudden impedance discontinuity in the radio frequency signal path will lead to signal reflection and standing wave formation, the π-type attenuator itself has a certain input and output impedance, but during the switching on or off process, it will cause instantaneous impedance jump. By adding a first voltage divider and a second voltage divider on both sides of the π-type attenuator, it plays the role of buffering impedance jump, reducing reflection, ensuring a stable attenuation value in the ultra-wideband range, effectively suppressing high-frequency reflection, making the frequency response more stable, the amplitude response closer to the target attenuation value, improving bandwidth consistency, and thus improving attenuation accuracy.

[0033] Specifically, the voltage divider device can be a single resistor element or a network of multiple resistors connected in series or parallel. The first attenuation unit is used to insert into the signal path for attenuation when 16dB attenuation is required. When the first and second switching devices are closed, the signal flows through the entire first attenuation module to complete the signal attenuation.

[0034] In another alternative, such as Figure 2As shown, the first conduction control module 14 includes: a third switching device S3, a first energy storage device L1, and a fourth switching device S4; wherein, the first end of the third switching device S3 is the first end of the first conduction control module 14, the second end of the third switching device S3 is electrically connected to the first end of the first energy storage device L1, the first end of the fourth switching device S4 is electrically connected to the second end of the first energy storage device L1, and the second end of the fourth switching device S4 is the second end of the first conduction control module 14.

[0035] In the above embodiments, the first conduction control module introduces a series connection structure of a third switching device, a first energy storage device, and a fourth switching device. This allows the current to not only be switched on and off during conduction by the control of the switching devices, but also to buffer current changes with the help of the energy storage device. This effectively reduces electromagnetic interference and energy loss caused by sudden current changes during switching, thereby improving circuit stability. When the third switching device S3 is closed, the energy storage device begins to store energy, and then releases the energy under the control of the fourth switching device, achieving flexible current transfer. Compared to a conduction scheme containing only one switching device, this structure can enhance the circuit's adaptability to dynamic current changes while maintaining the conduction control function, thereby improving the response speed and anti-interference capability of the entire digitally controlled attenuator in high-speed and high-frequency application scenarios.

[0036] Specifically, the first conduction control module is turned on when both the third and fourth switching devices are closed.

[0037] In some exemplary embodiments of this application, the resistance values ​​of the first voltage divider device and the second voltage divider device are the same.

[0038] In the above embodiments, the first voltage divider and the second voltage divider are located on the input side and the output side of the π-type attenuator, respectively. By setting the first voltage divider and the second voltage divider to the same resistance value, the voltage division value of the input signal on the first voltage divider and the second voltage divider will be consistent. As a result, the potentials at both ends of the first attenuation module are equal or approximately equal, reducing the phase shift caused by voltage division imbalance and thus improving the attenuation accuracy.

[0039] Specifically, the resistance of the first voltage divider and the second voltage divider is greater than or equal to 20Ω and less than or equal to 50Ω.

[0040] In some further exemplary embodiments of this application, the first voltage divider device includes a plurality of resistors connected in parallel or in series.

[0041] In the above embodiments, by combining multiple resistors, the total resistance value of the voltage divider device can be precisely designed to adapt to different target attenuation values. Furthermore, the combination of multiple resistors reduces the impact of individual resistor value deviations on the total resistance value, improving anti-interference capability. In addition, compared to a single large-value resistor, connecting multiple small-value resistors in series or parallel reduces parasitic capacitance and inductance effects, thereby preventing signal changes caused by input / output signal waveform distortion and further improving attenuation accuracy.

[0042] In one alternative, such as Figure 3 As shown, one of the aforementioned attenuation units with different target attenuation values ​​connected in series is a second attenuation unit. The second attenuation unit includes a second conduction control module 20 and a second attenuation module 22. The second attenuation module 22 includes a second π-type attenuator 24, a fifth switching device S5, a sixth switching device S6, a second energy storage device C1, and a third energy storage device C2. The first terminal of the fifth switching device S5 serves as the first terminal of the second attenuation module 22, and the second terminal of the fifth switching device S5 is electrically connected to the first terminal of the second π-type attenuator 24. The second end of the π-type attenuator 24 is electrically connected to the first end of the sixth switching device S6. The second end of the sixth switching device S6 serves as the second end of the second attenuation module 22. The first end of the second energy storage device C1 is electrically connected to the first end of the second π-type attenuator 24. The first end of the third energy storage device C2 is electrically connected to the second end of the second π-type attenuator 24. The second ends of the second energy storage device C1, the third energy storage device C2, the third end of the second π-type attenuator 24, and the fourth end of the second π-type attenuator 24 are all grounded.

[0043] In the above embodiments, by placing the fifth and sixth switching devices on opposite sides of the second π-type attenuator, the signal flows completely through the attenuation path during operation, ensuring the continuity and stability of the attenuation path, expanding its bandwidth, and improving its attenuation accuracy. Since the die size of the switching devices introduces equivalent capacitance and equivalent inductance, this leads to additional phase shift at high frequencies, weakening the π-type attenuator's control over the signal. This is especially problematic when frequency variations are large, causing phase response distortion. Therefore, an energy storage device is connected in parallel with the resistor in the second π-type attenuator and grounded, forming a low-impedance charge path on both sides of the signal path. Adjusting the capacitance of the energy storage device optimizes its additional phase shift, effectively expanding the overall bandwidth of the attenuator and improving its attenuation accuracy.

[0044] Specifically, when the fifth and sixth switching devices are closed, the signal flows through the entire second attenuation module, completing the signal attenuation. When the second conduction circuit is on, the second attenuation module fails.

[0045] like Figure 2 As shown, the second π-type attenuator includes a third voltage divider R3, a fourth voltage divider R4, and a fifth voltage divider R5. The first end of the third voltage divider R3 is electrically connected to the first end of the fourth voltage divider R4, and the second end of the third voltage divider R3 is electrically connected to the first end of the fifth voltage divider. The second ends of the fourth voltage divider R4 and the fifth voltage divider R5 are both grounded.

[0046] Traditional 8dB attenuators with switching characteristics typically place the fifth and sixth switching devices in the branches of the two grounded resistors in the second π-type attenuator. The attenuator state is switched by turning the switches on and off. In this case, the second π-type attenuator is actually decomposed into two simple T-type attenuators connected in series with the switches and grounded. Since the bandwidth of the simple T-type attenuators is narrow, it cannot meet the ultra-wideband requirements. At this time, the broadband attenuation is a curve, and the attenuation accuracy deteriorates significantly. The improved solution can effectively expand the overall bandwidth of the attenuator and improve its attenuation accuracy.

[0047] Specifically, the second attenuation unit is used to insert attenuation into the signal path when 16dB attenuation is required.

[0048] In another alternative, the second energy storage device has the same capacitance value as the third energy storage device.

[0049] In the above embodiments, when the switch is in the on state, the parasitic effects at both ends of the attenuator introduce additional phase shifts due to phase inconsistency. If the capacitance values ​​of the energy storage devices are inconsistent, it may cause uneven phase shifts at both ends of the signal path, thereby affecting the overall transmission phase consistency. However, by setting the capacitance values ​​of the energy storage devices at both ends to be equal, equivalent capacitive compensation can be achieved at high frequencies to offset the asymmetric phase error caused by the structure or layout of the switch chip, further improving the stability of signal transmission.

[0050] In some exemplary embodiments, the third energy storage device is a capacitor.

[0051] In the above embodiments, the third energy storage device is set as a capacitor. Since the capacitor exhibits low impedance at high frequencies, its charging and discharging characteristics can suppress voltage spikes and oscillations during circuit switching, thereby reducing the inductive and capacitive coupling effects caused by switching. Compared with other energy storage components such as inductors, capacitors have a faster response speed and are more suitable for high-frequency digitally controlled attenuators, achieving better bandwidth and power performance matching while maintaining high adjustment accuracy.

[0052] In some other exemplary embodiments, the switching device described above is one of the following: CMOS, PIN diode, and MEMS.

[0053] In the above embodiments, different types of switching devices can be selected according to specific application scenarios. For example, using CMOS (Complementary Metal-Oxide-Semicomductor, a type of switching device) can realize low-power, easy-to-integrate digital control, which is suitable for communication systems with low and medium frequencies; using PIN diodes (P-type Intrinsic N-type Diode, a type of high-frequency switching device) can provide lower insertion loss and higher isolation in high-frequency radio frequency environments, which is suitable for occasions requiring signal integrity; using MEMS (Micro-Electro-Mechanical Systems, a type of switching device) can significantly reduce losses in high-frequency precision systems.

[0054] Compared to traditional switches, CMOS switching devices are smaller, consume less power, and have higher integration, making them suitable for radio frequency circuits. In the digitally controlled attenuator of this application, using CMOS switching devices simplifies the circuit structure, facilitates integration with digital control circuits, and effectively reduces power consumption. Furthermore, CMOS switches can be turned on and off under low voltage control, which is beneficial for precisely controlling the on / off state of each attenuation path, thereby improving the control accuracy and response speed of the attenuator in multi-stage attenuation configurations.

[0055] The above-mentioned switching devices are merely illustrative examples. Any device capable of achieving on / off control to realize the switching function is applicable.

[0056] Embodiments of this application also provide a numerically controlled attenuation system, including any of the numerically controlled attenuators described above.

[0057] In the above embodiments, by integrating the numerically controlled attenuator into the numerically controlled attenuation system, the technical advantages of the attenuation controller in ultra-wideband attenuation accuracy can be utilized, enabling the numerically controlled attenuation system to effectively reduce attenuation errors and improve attenuation accuracy even in a wideband operating environment.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A digitally controlled attenuator, characterized in that, include: Multiple attenuation units with different target attenuation values ​​connected in series, each of the attenuation units includes a conduction control module and an attenuation module connected in parallel, and the attenuation module includes an electrically connected π-type attenuator and a switching device; Specifically, when the conduction control module is on, the π-type attenuator in the attenuation module is ineffective; when the conduction control module is off and the switching device in the attenuation module is closed, the π-type attenuator is effective.

2. The numerically controlled attenuator according to claim 1, characterized in that, One of the attenuation units with different target attenuation values ​​connected in series is a first attenuation unit, and the first attenuation unit includes a first conduction control module and a first attenuation module; The first attenuation module includes a first π-type attenuator, a first switching device, a second switching device, a first voltage divider device, and a second voltage divider device; Wherein, the first end of the first switching device and the first end of the first conduction control module serve as the first end of the first attenuation unit; the second end of the first switching device is electrically connected to the first end of the first voltage divider; the second end of the first voltage divider is electrically connected to the first end of the first π-type attenuator; the second end of the first π-type attenuator is electrically connected to the first end of the second voltage divider; the second end of the second voltage divider is electrically connected to the first end of the second switching device; and the second end of the second switching device and the second end of the first conduction control module serve as the second end of the first attenuation unit.

3. The numerically controlled attenuator according to claim 2, characterized in that, The first conduction control module includes: The third switching device, the first energy storage device, and the fourth switching device; Wherein, the first end of the third switching device is the first end of the first conduction control module, the second end of the third switching device is electrically connected to the first end of the first energy storage device, the first end of the fourth switching device is electrically connected to the second end of the first energy storage device, and the second end of the fourth switching device is the second end of the first conduction control module.

4. The numerically controlled attenuator according to claim 2, characterized in that, The first voltage divider and the second voltage divider have the same resistance.

5. The numerically controlled attenuator according to claim 2, characterized in that, The first voltage divider device includes multiple resistors connected in parallel or in series.

6. The numerically controlled attenuator according to claim 1, characterized in that, One of the attenuation units with different target attenuation values ​​connected in series is a second attenuation unit, and the second attenuation unit includes a second conduction control module and a second attenuation module; The second attenuation module includes a second π-type attenuator, a fifth switching device, a sixth switching device, a second energy storage device, and a third energy storage device; Wherein, the first end of the fifth switching device serves as the first end of the second attenuation module, the second end of the fifth switching device is electrically connected to the first end of the second π-type attenuator, the second end of the second π-type attenuator is electrically connected to the first end of the sixth switching device, the second end of the sixth switching device serves as the second end of the second attenuation module, the first end of the second energy storage device is electrically connected to the first end of the second π-type attenuator, the first end of the third energy storage device is electrically connected to the second end of the second π-type attenuator, and the second end of the second energy storage device, the second end of the third energy storage device, the third end of the second π-type attenuator, and the fourth end of the second π-type attenuator are all grounded.

7. The numerically controlled attenuator according to claim 6, characterized in that, The second energy storage device has the same capacitance value as the third energy storage device.

8. The numerically controlled attenuator according to claim 6, characterized in that, The third energy storage device is a capacitor.

9. The numerically controlled attenuator according to claim 1, characterized in that, The switching device is one of the following: CMOS, PIN diode, and MEMS.

10. A numerically controlled attenuation system, characterized in that, include: The numerically controlled attenuator according to any one of claims 1 to 9.

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