CN114397499B - A wideband current divider with gain buffer and adjustment method - Google Patents
A wideband current divider with gain buffer and adjustment method Download PDFInfo
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- 238000005259 measurement Methods 0.000 abstract description 4
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- 238000013461 design Methods 0.000 description 4
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/146—Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
本申请公开了一种带增益缓冲器宽频分流器，包括顺序连接的电阻单元、增益缓冲器、电压输出单元。增益缓冲器包含三级放大器，输入电压并联输入第一放大器负输入端、第二放大器正输入端、第三放大器正输入端；第一放大器输出反馈正输入端，第二放大器输出反馈负输入端、第三放大器输出反馈负输入端；第一放大器输出至第二放大器直流供电公共端、第二放大器输出至第三放大器直流供电公共端；第三放大器输出端与地之间接负载电阻。增益缓冲器包含卸载电路，连接于第二放大器输出端和第三放大器输出端之间，使第三放大器处于非带载状态。本申请还提出带增益缓冲器宽频分流器调节方法。本申请解决小电流测量精度受电磁环境影响的问题。
The present application discloses a broadband shunt with a gain buffer, comprising a resistor unit, a gain buffer, and a voltage output unit connected in sequence. The gain buffer comprises a three-stage amplifier, wherein the input voltage is input in parallel to the negative input terminal of the first amplifier, the positive input terminal of the second amplifier, and the positive input terminal of the third amplifier; the output of the first amplifier is fed back to the positive input terminal, the output of the second amplifier is fed back to the negative input terminal, and the output of the third amplifier is fed back to the negative input terminal; the output of the first amplifier is fed back to the DC power supply common terminal of the second amplifier, and the output of the second amplifier is fed back to the DC power supply common terminal of the third amplifier; a load resistor is connected between the output terminal of the third amplifier and the ground. The gain buffer comprises an unloading circuit, which is connected between the output terminal of the second amplifier and the output terminal of the third amplifier, so that the third amplifier is in a non-loaded state. The present application also proposes an adjustment method for a broadband shunt with a gain buffer. The present application solves the problem that the accuracy of small current measurement is affected by the electromagnetic environment.
Description
Technical Field
The application relates to the technical field of electronics, in particular to a broadband shunt with a gain buffer and an adjusting method.
Background
In high-precision current measurement, the role of the shunt is to convert the current into voltage, and the error caused by the shunt dominates the measurement error. The broadband gain buffer is mainly used for measuring mA magnitude alternating current and direct current. According to ohm's law, a shunt is connected in series in the circuit, and the measured voltage is divided by the resistance value of the shunt to calculate the current value in the circuit. The measuring error of the mA-magnitude current divider is easily influenced by external electromagnetic interference, noise and other factors.
When measuring small currents, the resistance value is larger, the influence of capacitance parameters of the shunt is larger, and the influence of input capacitance of a voltmeter for measuring voltage can further aggravate the influence. Finally, in measuring the ac power, the voltage signal obtained from the shunt is required to maintain the phase of the current. The voltage across the shunt is no longer in phase with respect to the phase of the current, creating an additional phase shift, although the impedance modulus of the shunt may not change much when the shunt is passing an alternating current. This places higher demands on the ac parameters of the shunt, and how to reduce the additional phase shift of the shunt becomes a key technique for measuring ac power. In addition, in designing the shunt, it is also necessary to consider the influence of inductance, thermal effect, interference resistance, and the like.
Disclosure of Invention
The application provides a broadband current divider with a gain buffer and an adjusting method, and solves the problem that small current measurement accuracy is affected by electromagnetic environment. In order to avoid the above drawbacks of the prior art, the present application is directed to an in-phase broadband shunt to meet the calibration requirement of high-precision current.
On one hand, the embodiment of the application provides a broadband current divider with a gain buffer, which comprises a resistor unit, the gain buffer and a voltage output unit which are sequentially connected. Wherein,
The shunt resistance value of the resistance unit is a set resistance value, and the voltage output unit is a cable with a matched joint;
The gain buffer comprises three stages of amplifiers, and input voltages are input into the negative input end of the first amplifier, the positive input end of the second amplifier and the positive input end of the third amplifier in parallel; the first amplifier outputs to the second amplifier DC power supply public end, the second amplifier outputs to the third amplifier DC power supply public end, the third amplifier output end and the ground are connected with a load resistor R L;
The gain buffer comprises an unloading circuit which is connected between the output end of the second amplifier and the output end of the third amplifier, so that the third amplifier is in an off-load state.
Preferably, the unloading circuit comprises an unloading resistor R ext, a fourth amplifier, a first voltage dividing resistor R 1 and a second voltage dividing resistor R 2, wherein the unloading resistor is connected between the output end of the third amplifier and the output end of the fourth amplifier, the output end of the second amplifier is connected with the negative input end of the fourth amplifier, the second voltage dividing resistor is connected between the output end of the fourth amplifier and the positive input end of the fourth amplifier in a bridging mode, and the first voltage dividing resistor is connected between the positive input end of the fourth amplifier and the ground in a bridging mode.
Preferably, R ext＝RLR2/R1.
Preferably, the gain buffer AC/DC conversion error is less than 100uV/V at 200kHz and the phase error is less than 100 mu rad.
Preferably, the first and second amplifiers are high-speed amplifiers with external input FET stages. Preferably, the third amplifier is a precision amplifier.
Preferably, the input resistance unit uses a metal foil resistor, and the resistance accuracy reaches +/-0.005%.
Preferably, the cable of the voltage output unit is an N-type connector.
On the other hand, the application also provides a method for adjusting the broadband shunt with the gain buffer, which is used for the broadband shunt with the gain buffer according to any one embodiment of the application, and comprises the following steps:
parameters of the first amplifier, the second amplifier and the third amplifier are adjusted, so that differences of output amplitudes of the first amplifier, the second amplifier and the third amplifier are smaller than set errors;
and adjusting the resistance value of the unloading circuit to enable the third amplifier to be in an unloaded state.
When the unloading circuit comprises an unloading resistor and a voltage dividing resistor, the adjusting method comprises the following steps of adjusting the resistance value to enable R ext＝RLR2/R1.
The above at least one technical scheme adopted by the embodiment of the application can achieve the following beneficial effects:
The gain buffer unit adopts a three-stage amplifying design, and the circuit has the functions of buffering, isolating and improving the carrying capacity. The three-stage amplification design of the gain buffer can enable amplitude errors and phase errors of the current converter to be obviously reduced. The current divider also has the characteristics of small temperature coefficient of resistance, good long-term stability, wide frequency characteristic, small heating value and the like, and is suitable for being used as a standard.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
FIG. 1 is a schematic block diagram of a broadband splitter;
FIG. 2 is a schematic diagram of a gain buffer circuit;
FIG. 3 is an embodiment of a method for tuning a broadband shunt with gain buffer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The following describes in detail the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.
Fig. 1 shows a schematic block diagram of a broadband shunt, which includes a shunt resistor unit 11, a gain buffer unit 12, and a voltage output unit (not shown).
The input of the shunt resistance unit is the input of the shunt, and the output of the shunt resistance unit 11 is connected to the input of the voltage follower gain buffer unit 12. The gain buffer unit is connected to the voltage output unit. The rear end of the voltage output unit is a shunt output end.
In the optimal embodiment of the broadband current divider, the resistance value is set to 800 omega, and the broadband current divider can be used for testing currents of 0.1 mA-1 mA and DC-100 kHz.
The working principle of the invention is that the broadband current signal is packaged into the broadband voltage signal through the shunt resistor unit, then the broadband voltage signal reaches the consistency of amplitude and phase with the front end through the gain buffer, the rear end adopts the precise phase voltmeter to measure the voltage and phase, and the accurate current value is obtained through calculation.
The shunt resistor of the shunt of the invention adopts a metal foil resistor. The metal foil has small temperature coefficient of resistance, good long-term stability, wide frequency characteristic and small heating value. For example, the shunt resistor unit is a metal foil resistor of Vishay in the United states, and the resistor is made of alloy foil, and has the advantages of small temperature coefficient, higher stability and reliability, higher long-term stability (delta R/R is less than or equal to 0.5%), small residual inductance, remarkably improved frequency characteristic, good electrical property, small heating value, low power consumption and small noise when loaded by adopting metal alloy. The resistance of the shunt resistor is 800 omega, so that 1mA and DC-100 kHz current can be converted into 0.8V voltage. The consumption power of the current-dividing resistor is 0.8mW when the current-dividing resistor passes through 1mA, and the resistor can meet the requirement through the power.
The maximum input voltage of the gain buffer circuit is 5V, the load resistance is 50 omega-10 MΩ, the maximum load capacitance is 200pF, the AC-DC conversion error is smaller than 100uV/V at 200kHz, and the phase error is smaller than 100 mu rad at 200 kHz. Additionally, the circuit input impedance reaches 10mΩ or higher and the input capacitance is less than 20pF. To ensure system stability, the front end input of the gain buffer is less than 5V.
The voltage output unit transmission line uses 50Ω cable, and the interface is N model joint, and the purpose is to reduce transmission error. The output end is connected with the precise phase voltmeter to measure voltage and phase, and an accurate current value is obtained through calculation.
Fig. 2 is a schematic diagram of a gain buffer circuit.
The gain buffer has three stages of amplifiers for design amplification, and the difference is very small. The gain buffer circuit diagram gives all the parameters of the gain buffer basic circuit diagram. The input voltage Vin of the gain buffer is applied to three unity gain voltage followers A1-A3. The output V out1 of the first amplifier A1 is the common terminal of the dc supply of the second amplifier A2. Similarly, the output terminal V out2 of the second amplifier A2 is the common terminal of the dc power supply of the third amplifier A3. As shown in the figure, in the circuits connected to the amplifiers A2 and A3, the two sides of the dc power supply common terminal are respectively provided with positive and negative bias voltages to the power supply terminals of the amplifiers. The three stages of amplifiers A1, A2, A3 of the gain buffer have approximately the same amplitude and decreasing phase errors. The second amplifier A2 greatly reduces the phase error of the first amplifier A1. However, the second amplifier A2 does not necessarily have to reduce the amplitude error of the first amplifier A1 due to the phase error factor of the second amplifier A2. A third amplifier A3 with a slightly different input voltage than the second amplifier A2 will significantly reduce the amplitude error of the system while also reducing the phase error. The dc error and noise performance of the gain buffer is determined by the third amplifier A3. Preferably, the third amplifier is a precision amplifier. The first amplifier A1 and the second counter-region A2 comprise a high-speed amplifier with externally input FET stages capable of increasing input impedance and decreasing input current. The system currents from A1 and A3 generate a voltage of about 1V at the input resistor Rin.
The gain buffer comprises an unloading circuit which is connected between the output end of the second amplifier and the output end of the third amplifier, so that the third amplifier is in an off-load state.
The three-stage amplification design of the gain buffer can greatly reduce amplitude errors and phase errors of the 1mA current converter in a DC-100 kHz state, and higher requirements are met.
In the embodiment with the fourth amplifier, the fourth amplifier A4 and the external dump resistor R ext are used to increase the drive current of the gain buffer. The appropriate resistor R L is selected so that R ext＝RLR2/R1 ensures that the third amplifier A3 is in an unloaded state.
FIG. 3 is an embodiment of a method for tuning a broadband shunt with gain buffer.
The application also provides a method for adjusting the broadband shunt with the gain buffer, which is used for the broadband shunt with the gain buffer according to any one embodiment of the application, and comprises the following steps:
Step 41, adjusting parameters of at least one of the first amplifier, the second amplifier and the third amplifier to enable differences of output amplitudes of the first amplifier, the second amplifier and the third amplifier to be smaller than set errors;
Step 42, adjusting the resistance value of the unloading circuit to make the third amplifier in the non-loaded state.
When the unloading circuit comprises an unloading resistor and a voltage dividing resistor, the application also provides a broadband shunt adjusting method with a gain buffer, which comprises the following steps:
Step 51, adjusting parameters of at least one of the first amplifier, the second amplifier and the third amplifier to enable output amplitude values of the first amplifier, the second amplifier and the third amplifier to be smaller than set errors;
And step 52, adjusting the resistance value to enable R ext＝RLR2/R1.
When the fourth amplifier is provided with the unloading circuit, the value of each resistor in the unloading circuit is adjusted or the value of the load resistor of the third amplifier is adjusted, so that the third amplifier is in an unloaded state.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.
Claims (9)
1. The broadband current divider with the gain buffer is characterized by comprising a resistor unit, the gain buffer and a voltage output unit which are connected in sequence;
The shunt resistance value of the resistance unit is a set resistance value, and the voltage output unit is a cable with a matched joint;
The gain buffer comprises three stages of amplifiers, and input voltages are input into the negative input end of the first amplifier, the positive input end of the second amplifier and the positive input end of the third amplifier in parallel; the first amplifier outputs to the second amplifier DC power supply public end, the second amplifier outputs to the third amplifier DC power supply public end, the third amplifier output end and the ground are connected with a load resistor R L;
the gain buffer comprises an unloading circuit which is connected between the output end of the second amplifier and the output end of the third amplifier to enable the third amplifier to be in an unloaded state;
The unloading circuit comprises an unloading resistor R ext, a fourth amplifier, a first voltage dividing resistor R 1 and a second voltage dividing resistor R 2, wherein the unloading resistor is connected between the output end of the third amplifier and the output end of the fourth amplifier, the output end of the second amplifier is connected with the negative input end of the fourth amplifier, the second voltage dividing resistor is connected between the output end of the fourth amplifier and the positive input end in a bridging mode, and the first voltage dividing resistor is connected between the positive input end of the fourth amplifier and the ground in a bridging mode.
2. The broadband splitter with gain buffer as set forth in claim 1, wherein,
Rext=RLR2/R1。
3. The broadband splitter with gain buffer as set forth in claim 1, wherein,
The AC/DC conversion error of the gain buffer is smaller than 100uV/V at 200kHz, and the phase error is smaller than 100 mu rad.
4. The broadband splitter with gain buffer as set forth in claim 1, wherein,
The first and second amplifiers are high-speed amplifiers with external input FET stages.
5. The broadband splitter with gain buffer as set forth in claim 1, wherein,
The third amplifier is a precision amplifier.
6. The broadband splitter with gain buffer as set forth in claim 1, wherein,
The input resistor unit uses a metal foil resistor, and the resistance precision reaches +/-0.005%.
7. The broadband splitter with gain buffer as set forth in claim 1, wherein,
The cable of the voltage output unit is an N-type connector.
8. A method for adjusting a broadband shunt with gain buffer, which is used for the broadband shunt with gain buffer according to any one of claims 1 to 7, and is characterized by comprising the following steps:
parameters of the first amplifier, the second amplifier and the third amplifier are adjusted, so that differences of output amplitudes of the first amplifier, the second amplifier and the third amplifier are smaller than set errors;
and adjusting the resistance value of the unloading circuit to enable the third amplifier to be in an unloaded state.
9. A method for adjusting a broadband shunt with gain buffer, which is used for the broadband shunt with gain buffer according to any one of claims 1 to 7, and is characterized by comprising the following steps:
The resistance value was adjusted to make R ext=RLR2/R1.
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| AUPQ894200A0 (en) * | 2000-07-24 | 2000-08-17 | Bhc Consulting Pty Ltd | Low distortion amplifier |
| US6600299B2 (en) * | 2001-12-19 | 2003-07-29 | Texas Instruments Incorporated | Miller compensated NMOS low drop-out voltage regulator using variable gain stage |
| US7253680B2 (en) * | 2003-05-21 | 2007-08-07 | World Energy Labs (2), Inc. | Amplifier system with current-mode servo feedback |
| CN100505524C (en) * | 2006-07-21 | 2009-06-24 | 联发科技股份有限公司 | limiting amplifier |
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| KR102285439B1 (en) * | 2019-07-26 | 2021-08-02 | 이화여자대학교 산학협력단 | Trans-impedance amplifier |
| CN215005603U (en) * | 2021-01-28 | 2021-12-03 | 江苏集萃智能集成电路设计技术研究所有限公司 | Power Detector Circuit and Current Feedback Loop |
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