CN112054773A - Amplifying circuit, power analyzer and measuring device - Google Patents

Amplifying circuit, power analyzer and measuring device Download PDF

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Publication number
CN112054773A
CN112054773A CN201910491164.1A CN201910491164A CN112054773A CN 112054773 A CN112054773 A CN 112054773A CN 201910491164 A CN201910491164 A CN 201910491164A CN 112054773 A CN112054773 A CN 112054773A
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node
input
feedback
coupled
inverting input
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赵章琰
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Fluke Corp
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Fluke Corp
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor
    • G01R21/06—Arrangements for measuring electric power or power factor by measuring current and voltage
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/3036—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Amplifiers (AREA)

Abstract

The application discloses an amplifying circuit, a power analyzer and a measuring device. The amplifying circuit comprises an operational amplifier, a voltage division network and a feedback network. The operational amplifier comprises a non-inverting input node, an inverting input node and an output node, wherein the non-inverting input node is coupled to a reference voltage; a voltage divider network coupled between an input signal and an inverting input node, the voltage divider network including a receiving node for receiving the input signal, an intermediate node coupled to the inverting input node, a first input resistor, a first input capacitor, and a second input capacitor coupled in series between the intermediate node and a reference voltage; a feedback network is coupled between the inverting input node and the output node.

Description

Amplifying circuit, power analyzer and measuring device
Technical Field
The present application relates to electronic circuits, and more particularly, to an amplification circuit and a power analyzer and a measurement device including the same.
Background
The power analyzer can be used for measuring power parameters of power conversion devices such as motors, frequency converters, transformers and the like, such as active power, reactive power or apparent power and the like. Power analyzers typically include an input stage circuit to convert the high voltage signal of the device under test to a lower voltage signal, which is input to an analysis circuit for analysis. The structure of the input stage circuit can significantly affect the performance of the power analyzer.
Disclosure of Invention
An object of the present invention is to provide an amplifier circuit having a simple structure.
According to an aspect of the present application, there is provided an amplification circuit including: an operational amplifier comprising a non-inverting input node, an inverting input node, and an output node, the non-inverting input node coupled to a reference voltage; a voltage divider network coupled between an input signal and the inverting input node, the voltage divider network comprising: a receiving node for receiving an input signal; an intermediate node coupled to the inverting input node; a first input resistor and a first input capacitor coupled in parallel between the receive node and the intermediate node; and a second input capacitor coupled between the intermediate node and the reference voltage; and a feedback network coupled between the inverting input node and the output node.
In some embodiments, the feedback network includes one or more feedback branches, each coupled between the inverting input node and the output node.
In some embodiments, the feedback network comprises at least one feedback branch comprising a feedback resistor and a feedback capacitor coupled in parallel with each other.
In some embodiments, the at least one feedback branch further comprises a switch in series with the parallel coupled feedback resistor and feedback capacitor.
In some embodiments, the feedback network comprises at least one feedback branch comprising a switch.
In some embodiments, the voltage divider network further comprises: a second input resistor coupled between the intermediate node and the inverting input node.
In some embodiments, a product of a capacitance value of the first input capacitor and a resistance value of the first input resistor is equal to a product of a capacitance value of the second input capacitor and a resistance value of the second input resistor.
In some embodiments, the resistance value of the second input resistor is less than 10% of the resistance value of the first input resistor.
According to another aspect of the present application, there is also provided a power analyzer comprising an amplification circuit as described in the preceding aspect.
According to another aspect of the present application, there is also provided a measurement device comprising an amplification circuit as described in the preceding aspect.
The foregoing is a summary of the application that may be simplified, generalized, and details omitted, and thus it should be understood by those skilled in the art that this section is illustrative only and is not intended to limit the scope of the application in any way. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
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The above-described and other features of the present disclosure will become more fully apparent to those skilled in the art from the following detailed description and appended claims, taken in conjunction with the accompanying drawings. It is to be understood that the drawings and detailed description depict only exemplary embodiments of the disclosure and are not to be considered limiting of its scope. The contents of the present application will be described more clearly and in detail by referring to the accompanying drawings.
Fig. 1 shows a circuit configuration diagram of an amplifying circuit 100 according to an embodiment of the present application.
Detailed Description
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like reference numerals generally refer to like parts unless the context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter of the present application. It will be understood that aspects of the present disclosure, as generally described in the present disclosure and illustrated in the figures herein, may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which form part of the present disclosure.
Referring to fig. 1, fig. 1 schematically illustrates a circuit configuration diagram of an amplification circuit 100 according to an embodiment of the present application.
As shown in fig. 1, the amplification circuit 100 includes an operational amplifier 102, a voltage divider network 104, and a feedback network 106. The operational amplifier 102 includes a non-inverting input node (+), an inverting input node (-) and an output node. In some embodiments, the operational amplifier 102 may be an operational amplifier based on bipolar junction transistors, an operational amplifier based on field effect transistors, or an operational amplifier implemented based on other suitable devices.
The voltage divider network 104 is coupled to the input signal VinAnd the inverting input node of the operational amplifier 102 for the input signal VinSampling is performed. The voltage divider network 104 may divide the input signal V by a voltage division factor corresponding to its circuit configurationinPerforms voltage division and generates an amplitude smaller than the input signal VinIs sampled signal Vs。
The feedback network 106 is coupled between the inverting input node and the output node of the operational amplifier 102, which in conjunction with the voltage divider network 104 causes the operational amplifier 102 to be configured as an inverting amplification circuit configuration. Compared with the in-phase amplifying circuit, the inverting amplifying circuit can easily realize a circuit amplification gain smaller than 1, and a switch or a relay with higher withstand voltage does not need to be added in the voltage division network 104 in order to switch the amplification gain of the circuit, so that the structure of the amplifying circuit 100 is simplified and the size is reduced. For a power analyzer or similar electrical measurement device, a smaller circuit amplification gain of the inverting amplifier circuit may reduce a larger magnitude input voltage (e.g., 220V ac voltage) to a magnitude range suitable for an electronic measurement device (e.g., less than or equal to 12V, or less than or equal to 5V); in addition, when the inverting amplification circuit switches the amplification gain of the smaller circuit, only a low-voltage switch with smaller volume is needed; thus, the operational amplifier employing the inverting amplifier circuit structure is particularly suitable for portable electronic measuring devices. In addition, the smaller circuit amplification gain is also beneficial to realizing wide bandwidth output.
In some embodiments, feedback network 106 may include one or more feedback branches, and each feedback branch is individually coupled between an inverting input node and an output node. When the feedback network 106 includes a plurality of feedback branches, the plurality of feedback branches are connected in parallel with each other. The feedback branches may have the same or different feedback coefficients. Optionally, a switch may be coupled to each feedback branch for controlling the closing or opening of the feedback branch. Thus, by controlling the on or off state of the switch of each feedback branch, the circuit gain of the amplifying circuit 100 can be adjusted to accommodate the input signal VinOf different amplitudes. In some embodiments, each feedback branch may include a feedback resistor and a feedback capacitor coupled in parallel with each other, where the feedback resistor may be used to determine a feedback gain of the feedback branch, and the feedback capacitor may be used to: low-pass filtering to filter out high-frequency noise that may affect the measurement; the stability of the amplifying circuit is ensured; and in conjunction with a second input capacitor C as will be described in detail belowin2Together ensuring a flat frequency response characteristic of the amplifier circuit. In some embodiments, the feedback capacitor may have a smaller capacitance value, such as 1 picofarad to 200 picofarads, or other suitable capacitance value. In some embodiments, the resistance value of the feedback resistor may be 100 ohms to 500 kiloohms, or other suitable resistance value.
Specifically, as shown in FIG. 1, voltage divider network 104 includes a receiverNode IN, intermediate node IMN, first input resistor Rin1A first input capacitor Cin1And a second input capacitor Cin2. Wherein the receiving node IN is arranged for receiving an input signal Vin(ii) a The intermediate node IMN is coupled to the inverting input node of the operational amplifier 102; first input resistor Rin1And a first input capacitor Cin1Coupled IN parallel between a receiving node IN and the intermediate node IMN; second input capacitor Cin1Coupled in series between an intermediate node IMN and a reference voltage VrefTo (c) to (d); the feedback network 106 is coupled between the inverting input node and the output node OUT of the operational amplifier 102. As shown in FIG. 1, the feedback network 106 includes one or more feedback branches, each of which includes a feedback resistor R coupled in parallel with each otherfAnd a feedback capacitor CfAnd a switch S is further included for controlling the closing or opening of the feedback branch. In some embodiments, the non-inverting input node is coupled to a reference voltage Vref. The amplification circuit shown in fig. 1 may be based on an input signal VinVoltage of (2) to generate an output signal V in the form of a voltageoutWherein the second input capacitor Cin2The primary contribution to achieving a flat frequency response characteristic is that the capacitance value is typically large (e.g., several thousand picofarads or other suitable capacitance values). It can be seen that the output of the operational amplifier 102 does not directly drive the second input capacitor Cin2This can improve the stability of the amplification circuit 100 itself. In addition, the amplifying circuit 100 only has single-stage amplification, which is beneficial to reducing the circuit volume and effectively avoiding noise introduced into the circuit by multi-stage amplification.
For input signals V of alternating forminThe voltage divider network 104 has a voltage divider coefficient dependent on the first input capacitor Cin1And a second input capacitor Cin2In particular the sampling signal V generated at the intermediate node IMNsCan be represented by the following equation (1):
Figure BDA0002087064160000041
in the embodiment shown in fig. 1, the voltage divider network 104 further includes a second input resistor Rin2Second input resistor Rin2Coupled between the intermediate node IMN and the inverting input node of the operational amplifier 102. Due to the virtual short characteristic of the operational amplifier, the in-phase input node and the inverting input node can be considered to have the same potential, i.e., the potential of the in-phase input node is equal to the reference voltage Vref. Based on this, assume the reference voltage VrefAt zero, the circuit transfer function of the amplifier circuit 100 is represented by the following equation (2) (without taking into account the value of the feedback capacitance in the feedback network):
Figure BDA0002087064160000051
wherein R isfiRepresenting the resistance of the feedback resistor coupled in the selected feedback branch, R, depending on the operation of the particular circuitfiR may be selectedf1To RfnOr the feedback resistors Rf1To RfnIn parallel (multiple feedback branches are selected to be closed).
It can be seen that for an input signal of high frequency ac form, the circuit amplification gain of the amplification circuit 100 is affected by the second input resistor Rin2The larger the resistance value is, the smaller the circuit amplification gain is. In some embodiments, the second input resistor Rin2Can be set to a smaller value, e.g. the second input resistor Rin2Is smaller than the first input resistor Rin110% of the resistance value of (a). In some embodiments, the first input resistor Rin1May be 200 kilo-ohms to 100 mega-ohms (e.g., 2 mega-ohms), while the second input resistor Rin2May be 1 kiloohm to 500 kiloohms (e.g., 10 kiloohms), or other suitable resistance values.
Since the inverting input node is considered to be coupled to a reference voltage VrefAlso under the assumption of VrefZero, the input resistance of the amplifier circuit 100anti-RinRepresented by the following equation (3):
Figure BDA0002087064160000052
in some embodiments, the first input capacitor Cin1And the first input resistor Rin1Is equal to the product of the resistance values of the second input capacitor Cin2And the second input resistor Rin2This can reduce the number of poles of the amplifier circuit 100, and the input impedance R can be obtained from equation (3)inThe variation with frequency is flat, i.e. the frequency response curve of the amplifying circuit 100 is made more flat. In addition, when the first input capacitor Cin1And the first input resistor Rin1Is equal to the product of the resistance values of the second input capacitor Cin2And the second input resistor Rin2When the resistance values are multiplied, the gain H of the amplifier circuit 100 is equal to the gain H as shown in the above equation (2)
Figure BDA0002087064160000053
The gain of the amplifying circuit 100 is flat.
In some embodiments, corresponding to the first input resistor R abovein1And a second input resistor Rin2A first input capacitor Cin1May be 0.5 picofarads to 250 picofarads (e.g., 5 picofarads), while the second input resistor Cin2May have a capacitance of 100 picofarads to 50 kilopicofarads (e.g., 1000 picofarads), or other suitable capacitance values.
In some embodiments, the amplification circuit shown in the embodiments of the present application may be used in a power analyzer, or other measurement device. In particular, the amplifying circuit shown in the embodiments of the present application may be used in a portable power analyzer or a measuring device, for example, as an input stage circuit of the portable power analyzer or the measuring device to sample a voltage. It will be appreciated that for a power analyzer, in addition to the amplification circuit for sampling voltage shown in fig. 1, it may also include a current sampling circuit for sampling current, which may be, for example, an inductor or other similar current sampling or sensing circuit. By calculating the sampling current and the sampling voltage, the power analyzer can obtain the power of the device to be tested.
Other variations to the disclosed embodiments can be understood and effected by those skilled in the art from a study of the specification, the disclosure, the drawings, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the words "a" or "an" do not exclude a plurality. In the practical application of the present application, one element may perform the functions of several technical features recited in the claims. Any reference signs in the claims shall not be construed as limiting the scope.

Claims (10)

1. An amplification circuit, comprising:
an operational amplifier comprising a non-inverting input node, an inverting input node, and an output node, the non-inverting input node coupled to a reference voltage;
a voltage divider network coupled between an input signal and the inverting input node, the voltage divider network comprising:
a receiving node for receiving an input signal;
an intermediate node coupled to the inverting input node;
a first input resistor and a first input capacitor coupled in parallel between the receive node and the intermediate node; and
a second input capacitor coupled between the intermediate node and the reference voltage; and
a feedback network coupled between the inverting input node and the output node.
2. The amplification circuit of claim 1, wherein the feedback network comprises one or more feedback branches, each coupled between the inverting input node and the output node.
3. The amplification circuit of claim 1, wherein the feedback network comprises at least one feedback branch comprising a feedback resistor and a feedback capacitor coupled in parallel with each other.
4. The amplification circuit of claim 3, wherein the at least one feedback branch further comprises a switch in series with the parallel-coupled feedback resistor and feedback capacitor.
5. The amplification circuit of claim 1, wherein the feedback network comprises at least one feedback branch, the at least one feedback branch comprising a switch.
6. The amplifier circuit of claim 1, wherein the voltage divider network further comprises:
a second input resistor coupled between the intermediate node and the inverting input node.
7. The amplification circuit of claim 6, wherein the product of the capacitance value of the first input capacitor and the resistance value of the first input resistor is equal to the product of the capacitance value of the second input capacitor and the resistance value of the second input resistor.
8. The amplification circuit of claim 6, wherein the resistance value of the second input resistor is less than 10% of the resistance value of the first input resistor.
9. A power analyzer, characterized in that it comprises an amplifying circuit according to any one of claims 1 to 8.
10. A measuring device, characterized in that it comprises an amplifying circuit according to any one of claims 1 to 8.
CN201910491164.1A 2019-06-06 2019-06-06 Amplifying circuit, power analyzer and measuring device Pending CN112054773A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115598410A (en) * 2022-12-13 2023-01-13 成都爱旗科技有限公司（Cn） Power consumption acquisition system and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115598410A (en) * 2022-12-13 2023-01-13 成都爱旗科技有限公司（Cn） Power consumption acquisition system and method
CN115598410B (en) * 2022-12-13 2023-03-10 成都爱旗科技有限公司 Power consumption acquisition system and method

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