CN106936404B - High-precision broadband numerical control attenuator - Google Patents
High-precision broadband numerical control attenuator Download PDFInfo
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- CN106936404B CN106936404B CN201710149435.6A CN201710149435A CN106936404B CN 106936404 B CN106936404 B CN 106936404B CN 201710149435 A CN201710149435 A CN 201710149435A CN 106936404 B CN106936404 B CN 106936404B
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Abstract
The invention provides a high-precision broadband numerical control attenuator which comprises a numerical control attenuation circuit and a feedback compensation circuit, wherein one end of the feedback compensation circuit is connected between the input end and the output end of the numerical control attenuation circuit, the other end of the feedback compensation circuit is grounded, and a feedback capacitor and/or a feedback inductor corresponding to the impedance in the feedback compensation circuit are connected to the numerical control attenuation circuit according to the attenuation precision requirements of the numerical control attenuation circuit on the frequency band of an input signal and different frequency bands, so that the attenuation precision of a selected frequency band is adjusted. The invention can adjust the attenuation precision of the frequency band corresponding to the input signal of the numerical control attenuation circuit; and the influence on the electric characteristics such as the insertion loss of the numerical control attenuation circuit is small, and the problems of serious deterioration of the insertion loss, the input 1dB compression point, the input voltage standing wave coefficient and the output voltage standing wave coefficient and the like are avoided.
Description
Technical Field
The invention belongs to the field of attenuators in microwave single-chip microcomputer chips, and particularly relates to a high-precision broadband numerical control attenuator.
Background
The digital control attenuator is a control device for controlling the amplitude of radio frequency signals, is mainly used in a microwave communication system with the requirements of gain setting and control functions, is responsible for equalizing the gains of different channels, and is an indispensable part in a multi-channel system. The present invention has wide application in the application fields of various wireless application systems such as "smart" antennas, electronic countermeasure systems, smart weapon systems, broadband Communication, military radar, GSM (global System for Mobile Communication), PCS (Process Control System), 3GD, and the like.
The basic units of the single chip numerical control attenuator are generally three types: bridge T type (figure 1), T type (figure 2) and pi type (figure 3), according to the actual circuit requirement, select suitable unit structure for each attenuation bit, finally satisfy the design index. Due to the particularity of the single chip circuit, the circuit parameters can be optimally designed only in the early stage, when the circuit is finished, the actual electrical parameters are fixed, and only redesign is performed if adjustment is needed.
The attenuation precision is used as a key index of the numerical control attenuator, the performance and the application of the numerical control attenuator are directly determined, and in order to obtain a better attenuation precision index in the whole working frequency band, a broadband design technology can be adopted to carry out compromise processing on the attenuation precision. However, as the operating bandwidth of the circuit is increased, the overall attenuation precision is deteriorated by the method, and the application of the method is greatly limited. The other method is to adopt a smaller process line width, which brings better high-frequency characteristics through the progress of the process, but the reduction of the process line width also brings the problems of power margin reduction, circuit cost increase and the like which are not avoidable.
Disclosure of Invention
The invention provides a high-precision broadband numerical control attenuator, which aims to solve the problem of poor attenuation precision of the conventional numerical control attenuator.
According to a first aspect of the embodiments of the present invention, there is provided a high-precision broadband numerical control attenuator, including a numerical control attenuation circuit and a feedback compensation circuit, where one end of the feedback compensation circuit is connected between an input end and an output end of the numerical control attenuation circuit, and the other end is grounded, and according to attenuation precision requirements of frequency bands of signals input by the numerical control attenuation circuit, a feedback capacitor and/or a feedback inductor corresponding to impedance in the feedback compensation circuit is connected to the numerical control attenuation circuit to adjust attenuation precision of a selected frequency band, the feedback compensation circuit includes a plurality of feedback compensation branches, each of which includes a first transistor and a feedback capacitor and a feedback inductor connected in series, where a control end of the first transistor is used to input signals for controlling the feedback compensation branch to be connected to the numerical control attenuation circuit, the first end is connected between the input end and the output end of the numerical control attenuation circuit; the first free ends of the feedback capacitor and the feedback inductor which are connected in series are connected with the second end of the first transistor, and the second free end is grounded.
In an optional implementation manner, the feedback compensation circuit is connected to the digitally controlled attenuation circuit when the frequency of the input signal is higher than a preset frequency.
In another optional implementation manner, for a selected frequency band, the higher the attenuation accuracy requirement is, the larger the impedance of the feedback compensation circuit connected to the digitally controlled attenuation circuit is.
In another optional implementation manner, the feedback capacitor performs coarse adjustment on the impedance, and the feedback inductor performs fine adjustment on the impedance.
In another optional implementation manner, the control end of the first transistor controls the feedback compensation branch to access the signal of the digital control attenuation circuit through an isolation resistor input.
In another optional implementation manner, the first transistor is an HEMT tube, after the feedback inductor is connected in series with the feedback inductor, a first free end of the HEMT tube is grounded, the other free end of the HEMT tube is connected with a drain electrode of the HEMT tube, a source electrode of the HEMT tube is connected with a numerical control attenuation circuit, and a gate electrode of the HEMT tube inputs a signal for controlling a corresponding feedback compensation branch to be connected to the numerical control attenuation circuit through an isolation resistor.
In another optional implementation manner, the numerical control attenuation circuit comprises a HEMT tube M1dHEMT tube M2dResistance R1dResistance R2dResistance R3dResistance R4dResistance R5dAnd a resistance R6dIn which HEMT tube M1dSource and signal input terminal VINConnected, HEMT tube M1dDrain electrode of and signal output terminal VOUTConnected by a resistor R1dOne terminal and signal input terminal VINConnected by a resistor R1dAnother end of (1) and a signal output end VOUTConnected by a resistor R2dOne terminal and signal input terminal VINConnected by a resistor R2dAnother terminal of (1) and a resistor R3dOne end is connected with a resistor R, the connection point is e3dAnother end of (1) and a signal output end VOUTConnected, HEMT tube M2dIs connected with the connection point e, and an HEMT tube M2dSource and resistor R of4dIs connected to one end of a resistor R4dThe other end of (3) is grounded, and a resistor R6dOne end of and HEMT tube M1dIs connected to the gate of the resistor R6dIs connected with the control end A, and a resistor R5dOne end of and HEMT tube M2dGrid connection, R5dThe other end of the feedback loop is connected with a control end B, and the connection point e is connected with the feedback compensation circuit.
The invention has the beneficial effects that:
1. according to the invention, the attenuation precision of the frequency band corresponding to the input signal of the numerical control attenuation circuit can be adjusted by accessing the impedance with corresponding size to the numerical control attenuation circuit by using the feedback capacitor and/or the feedback inductor in the feedback compensation circuit according to the frequency band height of the input signal of the numerical control attenuation circuit and the attenuation precision requirements on different frequency bands; in addition, one end of the feedback compensation circuit is connected between the input end and the output end of the numerical control attenuation circuit, and the other end of the feedback compensation circuit is grounded, namely the other end of the feedback compensation circuit is not positioned between input and output signal paths of the numerical control attenuation circuit, so that the feedback compensation circuit has small influence on input/output impedance characteristics of the numerical control attenuation circuit, namely the influence on electric characteristics such as insertion loss of the numerical control attenuation circuit is small, and the problems of serious deterioration of the insertion loss, an input 1dB compression point, an input voltage standing wave coefficient and an output voltage standing wave coefficient and the like are avoided;
2. according to the invention, the frequency of the input signal of the numerical control attenuation circuit is higher than the preset frequency, namely when the input signal of the numerical control attenuation circuit is in a high frequency band, the feedback compensation circuit is controlled to be connected into the numerical control attenuation circuit, so that the influence of the introduction of the feedback compensation circuit on the attenuation precision of the input signal in the low frequency band can be avoided;
3. the invention can improve the attenuation precision requirement of the selected frequency band by increasing the impedance of the access numerical control attenuation circuit;
4. according to the attenuator, the impedance is coarsely adjusted by adopting the feedback capacitor, and the impedance is finely adjusted by adopting the feedback inductor, so that the attenuation precision adjusting accuracy of the attenuator can be improved.
Drawings
FIG. 1 is a conventional bridge T-type digitally controlled attenuator;
FIG. 2 is a conventional T-shaped digital attenuator;
FIG. 3 is a conventional pi-type digital attenuator;
FIG. 4 is a block diagram of the high precision broadband digital controlled attenuator of the present invention;
FIG. 5 is a circuit diagram of an embodiment of the high-precision broadband digitally controlled attenuator according to the present invention;
FIG. 6 is an attenuation topology of the present invention;
FIG. 7 is a graph showing the comparison between the insertion loss of the attenuator of the present invention and that of a conventional attenuator;
FIG. 8 is a diagram showing the comparison between the attenuation accuracy of the present invention and the attenuation accuracy of the conventional digitally controlled attenuator.
Detailed Description
In order to make the technical solutions in the embodiments of the present invention better understood and make the above objects, features and advantages of the embodiments of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the term "connected" is to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, or a communication between two elements, or may be a direct connection or an indirect connection through an intermediate medium, and a specific meaning of the term may be understood by those skilled in the art according to specific situations.
Referring to fig. 4, it is a circuit block diagram of the high precision bandwidth digitally controlled attenuator of the present invention. The high-precision bandwidth numerical control attenuator can comprise a numerical control attenuation circuit 110 and a feedback compensation circuit 120, wherein one end of the feedback compensation circuit 120 is connected between the input end and the output end of the numerical control attenuation circuit 110, and the other end of the feedback compensation circuit is grounded, so that a feedback capacitor and/or a feedback inductor corresponding to the impedance in the feedback compensation circuit 120 can be connected to the numerical control attenuation circuit 110 according to the attenuation precision requirements of the frequency band of the input signal of the numerical control attenuation circuit 110 and different frequency bands, and the attenuation precision of the selected frequency band can be adjusted.
The applicant finds that, when the frequency of the input signal of the digital controlled attenuation circuit is in a low frequency band, if the feedback compensation circuit 120 is connected to the digital controlled attenuation circuit 110, the attenuation accuracy of the low frequency band of the digital controlled attenuation circuit 110 will be affected. Therefore, in this patent, the feedback compensation circuit 120 is provided to be not connected to the digitally controlled attenuation circuit 110 when the input signal of the digitally controlled attenuation circuit 110 is in the low frequency band, and to be connected to the digitally controlled attenuation circuit 110 when the input signal of the digitally controlled attenuation circuit 110 is in the high frequency band. In order to distinguish the low frequency band from the high frequency band, it may be considered that the input signal of the digitally controlled attenuation circuit 110 is in the high frequency band when the frequency of the input signal of the digitally controlled attenuation circuit 110 is higher than a preset frequency. In addition, the applicant researches and discovers that the attenuation precision of the feedback compensation circuit 120 is higher as the impedance connected to the numerically controlled attenuation circuit 110 is increased for the selected frequency band. When the impedance of the feedback compensation circuit 120 connected to the digital control attenuation circuit 110 is adjusted, the feedback capacitor can perform coarse adjustment on the impedance, and the feedback inductor can perform fine adjustment on the impedance.
According to the embodiment, the attenuation precision of the frequency band corresponding to the input signal of the numerical control attenuation circuit can be adjusted by accessing the impedance with the corresponding size to the numerical control attenuation circuit by using the feedback capacitor and/or the feedback inductor in the feedback compensation circuit according to the frequency band height of the input signal of the numerical control attenuation circuit and the attenuation precision requirements on different frequency bands; in addition, one end of the feedback compensation circuit is connected between the input end and the output end of the numerical control attenuation circuit, and the other end of the feedback compensation circuit is grounded, namely the other end of the feedback compensation circuit is not positioned between the input signal path and the output signal path of the numerical control attenuation circuit, so that the feedback compensation circuit has small influence on the input/output impedance characteristic of the numerical control attenuation circuit, namely the influence on the electric characteristics such as the insertion loss of the numerical control attenuation circuit is small, and the problems of serious deterioration of the insertion loss, the input 1dB compression point, the input voltage standing wave coefficient and the output voltage standing.
Referring to fig. 5, a circuit diagram of an embodiment of the high-precision bandwidth digitally controlled attenuator according to the present invention is shown, in which the feedback compensation circuit is connected to the T-type digitally controlled attenuator shown in fig. 2, the feedback compensation circuit may include a plurality of feedback compensation branches, each of which may include a first transistor M, a feedback capacitor C and a feedback inductor L connected in series, where a control terminal of the first transistor M is used for inputting a signal for controlling the feedback compensation branch to access the digitally controlled attenuator circuit 110, a first terminal of the first transistor M is connected between the input terminal and the output terminal of the digitally controlled attenuator circuit 110, and a first free terminal of the feedback capacitor C and a feedback inductor L connected in series is connected to a second terminal of the first transistor M, and a second free terminal of the feedback capacitor C and the feedback inductor 35.
In this embodiment, the digitally controlled attenuator circuit 110 may include a HEMT (High Electron mobility transistor) M1dHEMT tube M2dResistance R1dResistance R2dResistance R3dResistance R4dResistance R5dAnd a resistance R6d. Wherein, HEMT tube M1dSource and signal input terminal VINConnected, HEMT tube M1dDrain electrode of and signal output terminal VOUTAre connected. Resistance R1dOne terminal and signal input terminal VINConnected by a resistor R1dAnother end of (1) and a signal output end VOUTAre connected. Resistance R2dOne terminal and signal input terminal VINConnected by a resistor R2dAnother terminal of (1) and a resistor R3dOne end is connected with a resistor R, the connection point is e3dAnother end of (1) and a signal output end VOUTAre connected. HEMT tube M2dIs connected with the connection point e, and an HEMT tube M2dSource and resistor R of4dIs connected to one end of a resistor R4dAnd the other end of the same is grounded. Resistance R6dOne end of and HEMT tube M1dIs connected to the gate of the resistor R6dIs connected with the control end A, and a resistor R5dOne end of and HEMT tube M2dGrid connection, R5dThe other end of the control end B is connected with the control end B, and the connection point e is connected with the feedback compensation circuit.
The feedback compensation circuit 120 may include a plurality of feedback compensation branches, each of which may include a feedback inductor, a feedback capacitor, a HEMT device, and an isolation resistor, wherein after the feedback inductor is connected in series with the feedback inductor, a first free end of the feedback inductor is grounded, another free end of the feedback inductor is connected to a drain of the HEMT device, a source of the HEMT device is connected to the digitally controlled attenuator circuit 110 (i.e., the connection point e), and a gate of the HEMT device inputs a signal for controlling the corresponding feedback compensation branch to access the digitally controlled attenuator circuit through the isolation resistor1dA feedback capacitor C1dHEMT tube M3dAnd an isolation resistor R7dAnd the second feedback compensation branch comprises a feedback inductor L2dA feedback capacitor C2dHEMT tube M4dAnd an isolation resistor R8dThe Nth feedback compensation branch comprises a feedback inductor LndA feedback capacitor CndHEMT tube M3+ndAnd an isolation resistor R7+ndWherein the feedback inductor L1dToTerminal connected to ground, feedback inductor L1dThe other end of (C) and a feedback capacitor (C)1dIs connected to one terminal of a feedback capacitor C1dAnother end of (3) and HEMT tube M3dIs connected with the drain electrode of the HEMT tube M3dIs connected to the connection point e, and an isolation resistor R7dOne end of and HEMT tube M3dGrid connected, isolating resistor R7dAnd the other end of the feedback inductor L is connected with the control end C2dIs connected to ground, the feedback inductor L2dThe other end of (C) and a feedback capacitor (C)2dOne end of the feedback capacitor C is connected2dThe other end is connected with the HEMT tube M4dIs connected with the drain electrode of the HEMT tube M4dIs connected to the connection point e, and an isolation resistor R8dOne end of and HEMT tube M4dGrid connected, isolating resistor R8dAnd the other end of the feedback inductor L is connected with the control end DndIs connected to ground, the feedback inductor LndThe other end of (C) and a feedback capacitor (C)ndOne end of the feedback capacitor C is connectedndThe other end is connected with the HEMT tube MndIs connected with the drain electrode of the HEMT tube M3+ndIs connected to the connection point e, and an isolation resistor R7+ndOne end of and HEMT tube M3+ndGrid connected, isolating resistor R7+ndThe other end of the second switch is connected with a control end N. The number N of the feedback loops is determined according to circuit design indexes. According to the invention, the isolation resistor is arranged between the transistor in the feedback compensation circuit and the signal for controlling the corresponding feedback compensation branch to be accessed to the numerical control attenuation circuit, so that sufficient isolation can be provided for the transistor and the signal, the transistor is damaged, and the stability of the circuit is improved.
The working principle of the embodiment is as follows: the working state of the numerical control attenuation circuit is controlled through the control ends A and B, and when the HEMT tube M1dIn an on state, the HEMT tube M2dHEMT tube M3dHEMT tube M4dHEMT tube MndWhen the digital controlled attenuation circuit is in an off state, the working state of the digital controlled attenuation circuit is a reference state, and the radio frequency signal passes through the VINAfter the port enters the numerical control attenuation circuit 110, the HEMT tube M1dWhen the HEMT is in a conducting state, the source and the drain are low impedance, and the impedance value is far lower than that of other branches, so that radio-frequency signals sequentially pass through the HEMT tube M1dSource and drain back from VOUTAnd (6) outputting the port.
When HEMT tube M1dIn an off state, the HEMT tube M2dHEMT tube M3dHEMT tube M4dHEMT tube MndWhen the digital control attenuation circuit is in a conducting state, the working state of the digital control attenuation circuit is in an attenuation state. As shown in FIG. 6, to this end, the network topology of the time-controlled attenuation circuit is a resistor R2dAnd a resistance R3dThe resistance values are generally the same, and the impedance is set to Z0Then the impedance parameter of the circuit topology can be expressed as:
the impedance of the first feedback compensation branch in the feedback compensation circuit is Z41The impedance of the second feedback compensation branch is Z42The Nth feedback compensation branch has an impedance of Z4NThen Z is4Is a resistance R4dAnd Z41、Z42Up to Z4NThe impedances formed are connected in parallel.
In equations (2) to (4), w represents the angular velocity of the input signal of the digitally controlled attenuator circuit.
Converting the impedance Z parameter in the formula (1) into an admittance S parameter, then:
after substituting equation (5) into equation (1), the S parameter of equation (7) can be obtained, and Z is obtained due to the access of the feedback compensation branch4Will vary with frequency: in the low frequency band of circuit operation, due to the low frequency S21Is substantially free of Z4(ii) an effect; in the high frequency range of circuit operation, Z4The impedance value becomes large so that S21And becomes smaller. Due to the frequency characteristics of the transistors, the insertion loss (reference state) of the digitally controlled attenuator circuit increases with increasing frequency, S21Just compensate for the attenuation accuracy.
Resistance R6dResistance R5dResistance R7dResistance R8dUp to the resistance R7+ndRespectively connected with HEMT tube M1dHEMT tube M2dHEMT tube M3dHEMT tube M4dUp to HEMT tube M3+ndThe gate of the HEMT is connected, the resistance value is generally 3-8K omega, and sufficient isolation is provided between the gate of the HEMT and the signal control end. Capacitor C1dResistance C2dUp to CndFor feedback capacitance, the attenuation precision of the digital control attenuation circuit is roughly adjusted at high frequency, generally the value is 0.02 pF-1 pF, when the capacitance value is too small, a plurality of small capacitors are generally adopted to be connected in parallel, the capacitor L1dResistor L2dUp to LndFor feedback inductance, the attenuation precision of the numerical control attenuation circuit is finely adjusted at high frequency, the value is generally 0.02 nH-1 nH, and when the inductance is too small, the inductance can be cancelled or a microstrip line is selected for replacement. When the digital control attenuation circuit is in a reference state, the radio frequency signal is from VOUTOutput signal amplitude and slave V of portINThe ratio of the amplitude of the input and output signals is numerical controlInsertion loss of the attenuation circuit; when the digital control attenuation circuit is in an attenuation state, the attenuation state is controlled by VINPort output signal amplitude and pass VOUTThe ratio of the amplitude of the input and output signals of the port is the attenuation value of the numerical control attenuation circuit; the attenuation of the numerical control attenuation circuit is the difference between the attenuation value and the insertion loss, and the accuracy of the attenuation is the attenuation precision.
Fig. 7 is a comparison of insertion loss of the high-precision broadband digital-controlled attenuator of the present invention with that of the conventional digital-controlled attenuator, wherein ○ is a relationship curve between insertion loss and frequency of the conventional digital-controlled attenuator (i.e., a first curve from top to bottom), ▽ is a relationship curve between insertion loss and frequency of the high-precision broadband digital-controlled attenuator of the present invention only including one feedback compensation loop (n is 1) (i.e., a second curve from top to bottom), △ is a relationship curve between insertion loss and frequency of the high-precision broadband digital-controlled attenuator of the present invention including two feedback compensation loops (n is 2) (i.e., a third curve from top to bottom), and ◇ is a relationship curve between insertion loss and frequency of the high-precision broadband digital-controlled attenuator of the present invention including three feedback compensation loops (n is 3) (i.e., a fourth curve from top to bottom).
Fig. 8 is a comparison of the attenuation accuracy of the conventional numerical control attenuator, wherein ○ is a relation curve between the attenuation accuracy and the frequency of the conventional numerical control attenuator (i.e., a first curve from top to bottom), △ is a relation curve between the attenuation accuracy and the frequency of the high-accuracy broadband numerical control attenuator of the present invention (i.e., a second curve from top to bottom) when only one feedback compensation loop (n is 1) is included, ▽ is a relation curve between the attenuation accuracy and the frequency of the high-accuracy broadband numerical control attenuator of the present invention (i.e., a third curve from top to bottom) when the high-accuracy broadband numerical control attenuator of the present invention includes two feedback compensation loops (n is 2), and ◇ is a relation curve between the attenuation accuracy and the frequency of the high-accuracy broadband numerical control attenuator of the present invention (i.e., a fourth curve from top to bottom) when the high.
The basic parameters of HEMT tube, resistance, capacitance and inductance in the circuit of the invention are as follows:
HEMT tube: | Vgs︱：0～15V，︱Vds︱：0～15V，︱Vbs︱：0～15V。
M1d、M2d、M3d、M4d…MndThe gate length of (2) is 0.5 μm;
M1dgate width of (d): 85 μm; m1dGate index of (d): 12;
M2dgate width of (d): 34 μm; m1dGate index of (d): 6;
M3d、M4d…Mndthe gate width of (2) is 25 μm; m3d、M4d…MndGate index of (d): 2;
resistance R5d、R6d、R7d、R8d…RndIs a polysilicon resistor;
resistance R1d、R2d、R3d、R4dIs a metal thin film resistor;
R5d、R6d、R7d、R8d…Rndthe resistance value of (1) is 5K omega;
R1dis 14 Ω;
R2d、R3dis 50 omega;
R4dis 160.7 omega;
R1dis 14 Ω;
inductor L1d、L2d…LndThe sensitivity values of (A) are all set as: 0.1 nH; capacitor C1d、C2d…CndThe capacity values of (A) are all set as: 0.025 pF.
As can be seen from the above embodiments, the feedback inductor L is added on the basis of the basic numerical control attenuation unit1dA feedback capacitor C1dHEMT tube M3dAnd an isolation resistor R7dFeedback inductor L2dA feedback capacitor C2dHEMT tube M4dAnd an isolation resistor R8dUp to the feedback inductor LndA feedback capacitor CndHEMT tube M3+ndAnd an isolation resistor R7+ndAnd forming a feedback compensation unit. When HEMT tube M3dIn the on state, inductor L1dAnd a capacitor C1dThe first feedback compensation branch is connected with a basic numerical control attenuation unit for attenuation in high frequency bandThe precision is optimized when the HEMT tube M3dWhen the circuit is in an off state, the first feedback compensation branch circuit is disconnected with the basic numerical control attenuation unit, so that the lower frequency attenuation precision of the basic numerical control attenuation unit is not influenced. Similarly, when HEMT tube M4dIn the on state, inductor L2dAnd a capacitor C2dThe second feedback compensation branch is connected with a basic numerical control attenuation unit to optimize the attenuation precision in high frequency band, and when the HEMT tube M4dWhen the second feedback compensation branch circuit is in an off state, the second feedback compensation branch circuit is disconnected with the basic numerical control attenuation unit; when HEMT tube MndIn the on state, inductor LndAnd a capacitor CndThe Nth feedback compensation loop is connected to the basic numerical control attenuation unit to optimize the attenuation precision in high frequency band, and when the HEMT tube M is connectedndAnd when the feedback compensation circuit is in an off state, the Nth feedback compensation circuit is disconnected with the basic numerical control attenuation unit.
Because of the feedback inductance L in the feedback compensation branchndValue and feedback capacitance CndThe value determines the compensation frequency and compensation amount of the attenuator attenuation accuracy, so that feedback inductor L is reasonably arranged in each feedback compensation branchndValue and feedback capacitance CndThe number of feedback compensation branches connected to the basic numerical control attenuation unit is controlled by controlling the on-off of the HEMT tube, so that the attenuation precision of the numerical control attenuation circuit can be compensated in a high-frequency band in a targeted manner, the attenuation precision which is higher than that of a traditional numerical control attenuator by more than 50% can be obtained in a selected high-frequency band by using the topological structure, and the use range of the frequency of the numerical control attenuator is expanded. The circuit of the invention can disconnect the feedback compensation loop when the numerical control attenuation circuit works in the low frequency band, so the attenuation precision of the low frequency band of the numerical control attenuator can not be influenced. In addition, the feedback compensation loop is not positioned in a signal path, and the influence on the input/output impedance characteristic of the numerical control attenuation circuit is small, so that the influence on the electric characteristic of the insertion loss of the numerical control attenuation circuit is small, and the problems of serious deterioration of the insertion loss, the input 1dB compression point, the input voltage standing wave coefficient, the output voltage standing wave coefficient and the like are solved.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (7)
1. A high-precision broadband numerical control attenuator is characterized by comprising a numerical control attenuation circuit and a feedback compensation circuit, wherein one end of the feedback compensation circuit is connected between the input end and the output end of the numerical control attenuation circuit, the other end of the feedback compensation circuit is grounded, a feedback capacitor and/or a feedback inductor corresponding to the impedance in the feedback compensation circuit is connected to the numerical control attenuation circuit according to the attenuation precision requirements of the numerical control attenuation circuit on the frequency bands of input signals and different frequency bands, so as to adjust the attenuation precision of the selected frequency band, the feedback compensation circuit comprises a plurality of feedback compensation branches, each feedback compensation branch comprises a first transistor, a feedback capacitor and a feedback inductor which are connected in series, the control end of the first transistor is used for inputting signals for controlling the feedback compensation branches to be connected to the numerical control attenuation circuit, the first end is connected between the input end and the output end of the numerical control attenuation circuit; the first free ends of the feedback capacitor and the feedback inductor which are connected in series are connected with the second end of the first transistor, and the second free end is grounded.
2. The high-precision broadband numerical control attenuator of claim 1, wherein the feedback compensation circuit is connected to the numerical control attenuator circuit when the frequency of the input signal is higher than a preset frequency.
3. A high precision broadband numerical control attenuator according to claim 1, wherein the higher the attenuation precision requirement is for a selected frequency band, the higher the impedance of the feedback compensation circuit connected to the numerical control attenuator circuit is.
4. The high-precision broadband numerical control attenuator of claim 1, wherein the feedback capacitor coarsely adjusts the impedance magnitude, and the feedback inductor finely adjusts the impedance magnitude.
5. The high-precision broadband numerical control attenuator according to claim 1, wherein the control end of the first transistor inputs a signal for controlling the feedback compensation branch to be connected to the numerical control attenuator circuit through an isolation resistor.
6. The high-precision broadband numerical control attenuator according to claim 1, wherein the first transistor is a HEMT tube, after the feedback inductor is connected in series with the feedback inductor, a first free end of the HEMT tube is grounded, the other free end of the HEMT tube is connected with a drain electrode of the HEMT tube, a source electrode of the HEMT tube is connected with a numerical control attenuation circuit, and a gate electrode of the HEMT tube inputs a signal for controlling a corresponding feedback compensation branch to be connected into the numerical control attenuation circuit through an isolation resistor.
7. A high precision broadband digitally controlled attenuator according to claim 1, wherein the digitally controlled attenuator circuit comprises a HEMT-tube M1dHEMT tube M2dResistance R1dResistance R2dResistance R3dResistance R4dResistance R5dAnd a resistance R6dIn which HEMT tube M1dSource and signal input terminal VINConnected, HEMT tube M1dDrain electrode of and signal output terminal VOUTConnected by a resistor R1dOne terminal and signal input terminal VINConnected by a resistor R1dAnother end of (1) and a signal output end VOUTConnected by a resistor R2dOne terminal and signal input terminal VINConnected by a resistor R2dAnother terminal of (1) and a resistor R3dOne end is connected with a resistor R, the connection point is e3dAnother end of (1) and a signal output end VOUTConnected, HEMT tube M2dIs connected with the connection point e, and an HEMT tube M2dSource and resistor R of4dIs connected to one end of a resistor R4dThe other end of (3) is grounded, and a resistor R6dOne end of and HEMT tube M1dIs connected to the gate of the resistor R6dIs connected with the control end A, and a resistor R5dOne end of and HEMT tube M2dGrid connection, R5dThe other end of the feedback loop is connected with a control end B, and the connection point e is connected with the feedback compensation circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710149435.6A CN106936404B (en) | 2017-03-14 | 2017-03-14 | High-precision broadband numerical control attenuator |
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| CN109995344B (en) * | 2019-05-10 | 2024-02-13 | 中国电子科技集团公司第三十四研究所 | Numerical control attenuation circuit and adjusting method thereof |
| CN111865266A (en) * | 2020-07-23 | 2020-10-30 | 慧讯圆成电子科技(南通)有限公司 | Adjustable stepping attenuation device and electronic equipment |
| CN112886943B (en) * | 2021-01-27 | 2023-07-18 | 中国电子科技集团公司第十三研究所 | Electric tuning attenuation circuit and electric tuning attenuator applied to terahertz frequency band |
| CN113472373B (en) * | 2021-06-30 | 2022-05-31 | 中国电子科技集团公司第二十九研究所 | Automatic equalization method for radio frequency signal output |
| CN113824439A (en) * | 2021-09-08 | 2021-12-21 | 西安博瑞集信电子科技有限公司 | Switch tube assembly, radio frequency switch circuit, numerical control attenuator circuit and numerical control phase shifter circuit |
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| CN104852706A (en) * | 2015-01-30 | 2015-08-19 | 黄华 | Low additional phase shift digital attenuator |
| CN105811894A (en) * | 2016-02-28 | 2016-07-27 | 杭州臻镭微波技术有限公司 | Equalizing network for broadband radio frequency amplifier, broadband radio frequency amplifier and adjusting method |
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| CN104852706A (en) * | 2015-01-30 | 2015-08-19 | 黄华 | Low additional phase shift digital attenuator |
| CN105811894A (en) * | 2016-02-28 | 2016-07-27 | 杭州臻镭微波技术有限公司 | Equalizing network for broadband radio frequency amplifier, broadband radio frequency amplifier and adjusting method |
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