CN106936395B - Linear voltage controlled amplifier - Google Patents
Linear voltage controlled amplifier Download PDFInfo
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- CN106936395B CN106936395B CN201710118756.XA CN201710118756A CN106936395B CN 106936395 B CN106936395 B CN 106936395B CN 201710118756 A CN201710118756 A CN 201710118756A CN 106936395 B CN106936395 B CN 106936395B
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- resistor
- triode
- amplifier
- linear voltage
- differential amplifier
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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
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3211—Modifications of amplifiers to reduce non-linear distortion in differential amplifiers
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- 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
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/4508—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using bipolar transistors as the active amplifying circuit
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- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
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Abstract
A linear voltage controlled amplifier comprising: the differential amplifier is connected with the linear voltage control current source, the amplification factor of the differential amplifier is controlled by a third end of the differential amplifier, the third end of the differential amplifier is connected with the output end of the linear voltage control current source, the first end of the differential amplifier is connected with an external input signal, and the second end of the differential amplifier is connected with a rear-end element; the input end of the linear voltage control current source is connected with an external voltage control signal and used for converting the input voltage control signal into output current, the output current and the input voltage control signal are in a linear relation, and the output end of the linear voltage control current source is connected with the third end of the differential amplifier; the amplification factor Av of the differential amplifier is K × VCON, where K is a constant. The linear voltage-controlled amplifier can realize linear/linear control characteristics.
Description
Technical Field
The invention belongs to a voltage-controlled amplifier, and particularly relates to a linear voltage-controlled amplifier.
Background
Voltage controlled amplifiers are widely used in analog circuits, but most of the current voltage controlled amplifiers have linear/logarithmic control characteristics, i.e. V/dB characteristics, but in some applications, linear/linear control characteristics, i.e. V/amplification factor characteristics, are required.
Disclosure of Invention
Aiming at the technical problem of frequency judgment failure in the prior art, the invention provides a novel linear voltage-controlled amplifier.
The invention provides a linear voltage-controlled amplifier, comprising: the differential amplifier is connected with the linear voltage control current source, the amplification factor of the differential amplifier is controlled by a third end of the differential amplifier, the third end of the differential amplifier is connected with the output end of the linear voltage control current source, the first end of the differential amplifier is connected with an external input signal, and the second end of the differential amplifier is connected with a rear-end element; the input end of the linear voltage control current source is connected with an external voltage control signal and used for converting the input voltage control signal into output current, the output current and the input voltage control signal are in a linear relation, and the output end of the linear voltage control current source is connected with the third end of the differential amplifier; the amplification factor Av of the differential amplifier is K × VCON, where K is a constant.
Wherein, the differential amplifier comprises a first triode, a second triode, a first resistor, a second resistor, a seventh resistor and a first capacitor, a fifth capacitor, one end of the second capacitor is used as the first end of the whole differential amplifier to be connected with an external input signal, the other end of the second capacitor is connected with the base electrode of the first triode, the collector electrode of the first triode is further connected with the base electrode thereof through the first resistor and the seventh resistor in sequence, the emitter electrode of the first triode is connected with the emitter electrode of the second triode, the collector electrode of the second triode is connected with an external power supply through the third resistor, the collector electrode of the second triode is further directly connected with one end of the first capacitor, the other end of the first capacitor is used as the second end of the whole differential amplifier to be connected with a rear end element, and the node between the first resistor and the collector electrode of the first triode is directly connected with the external power supply, the node between the external power supply and the third resistor is grounded sequentially through a fourth resistor and a fifth resistor, the fifth resistor is connected with a third capacitor in parallel, the node between the fourth resistor and the fifth resistor is connected with the base electrode of the second triode, the emitting electrodes of the first triode and the second triode are grounded sequentially through a sixth resistor and the fourth capacitor, the node between the sixth resistor and the fourth capacitor is used as the third end of the whole differential amplifier and is connected with the linear voltage control current source, the node between the first resistor and the seventh resistor is grounded through a second resistor, and the second resistor is connected with the fifth capacitor in parallel.
The linear voltage control current source comprises an operational amplifier, a third triode, an eighth resistor and a ninth resistor, wherein a positive phase input end of the operational amplifier is used as a first end of the whole linear voltage control current source and connected with a controlled voltage, a negative phase input end of the operational amplifier is grounded through the eighth resistor, the positive phase input end of the operational amplifier is also directly grounded through the ninth resistor, an output end of the operational amplifier is connected with a base electrode of the third triode, an emitting electrode of the third triode is directly connected with the negative phase input end of the third triode, and a collector electrode is used as a second end of the whole linear voltage control current source and connected with a third end of the differential amplifier 1.
And the collector of the third triode is connected to a node between the sixth resistor and the fourth capacitor.
Wherein the amplification factor Av of the differential amplifier is:
wherein R7 represents the resistance value of the third resistor R7, ITAIL represents the output current value of the linear voltage controlled amplifier.
Wherein, the output current ITAIL of the linear voltage-controlled amplifier is:
where VCON represents the voltage value of the controlled voltage and R6 represents the resistance value of the eighth resistor.
Wherein the amplification factor Av of the differential amplifier is: av ═ K × VCON, where
The first triode, the second triode and the third triode are all NPN tubes, and the cut-off frequency fT of the NPN tubes is required to be larger than 2 GHz.
Wherein the operational amplifier is a single voltage supply operational amplifier.
Wherein the operational amplifier is a voltage feedback operational amplifier.
Under the condition that the working temperature is-55-125 ℃, the linear voltage-controlled amplifier disclosed by the invention can normally work when the working voltage is more than 3V, the temperature stability is good, and the working bandwidth can reach 700 MHz. In addition, the linear voltage-controlled amplifier adopts fewer components, has small volume and low cost, and can be integrated by an IC (integrated circuit) so as to further reduce the volume. Meanwhile, the voltage-controlled amplifier does not need to be debugged, and is convenient for mass production.
Drawings
Fig. 1 is a block diagram of a preferred embodiment of a linear voltage controlled amplifier according to the present invention.
Fig. 2 is a circuit diagram of a preferred embodiment of a linear voltage controlled amplifier according to the present invention.
Fig. 3 is a diagram of the control characteristic of the measured result of the linear voltage controlled amplifier according to the preferred embodiment of the present invention.
Fig. 4 is a frequency characteristic diagram of a preferred embodiment of a linear voltage controlled amplifier according to the present invention.
In the figure, 1: a differential amplifier; 2: a linear voltage controlled current source; r2, R3, R6-R12: a resistance; C1-C5: a capacitor; Q2-Q4: a triode; u1: an operational amplifier.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the specific drawings.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Fig. 1 is a block diagram of a linear voltage-controlled amplifier according to a preferred embodiment of the present invention. The preferred embodiment of the linear voltage-controlled amplifier comprises a differential amplifier 1 and a linear voltage-controlled current source 2, wherein the differential amplifier 1 is connected with the linear voltage-controlled current source 2.
The amplification factor of the differential amplifier 1 is controlled by the third terminal ITAIL thereof, the third terminal is connected with the output terminal ICON of the linear voltage control current source 2, when the signal received by the third terminal ITAIL of the differential amplifier 1 is increased, the amplification factor of the differential amplifier 1 is increased, and when the signal received by the third terminal ITAIL is decreased, the amplification factor of the differential amplifier 1 is decreased. The differential amplifier 1 has a first end (input end) connected to an external input signal VIN, a second end (output end) connected to a back-end element, and a third end connected to an output end ICON of the linear voltage-controlled current source 2.
The linear voltage control current source 2 is used for converting an input voltage control signal VCON into an output current ICON, which is linearly related to the input voltage control signal VCON. The input terminal of the linear voltage control current source 2 is connected to an external voltage control signal VCON, and the output terminal ICON thereof is connected to the third terminal ITAIL of the differential amplifier 1.
Please refer to fig. 2, which is a circuit diagram of the linear voltage controlled amplifier of fig. 1 according to a preferred embodiment. The differential amplifier 1 comprises triodes Q3 and Q4, resistors R2, R3, R7-R9, R11, R12 and capacitors C1-C5, wherein one end of the capacitor C2 is used as the first end of the whole differential amplifier 1 and connected with an external input signal VIN, the other end of the capacitor C2 is connected with the base of the triode Q3, the collector of the triode Q3 is further connected with the base of the triode Q2 and R12 in sequence, the emitter of the triode Q3 is connected with the emitter of the triode Q4, the collector of the triode Q4 is connected with an external power supply VCC in sequence through a resistor R7, the collector of the triode Q4 is further directly connected with one end of the capacitor C1, and the other end of the capacitor C1 is used as the second end of the whole differential amplifier 1 and connected with a rear-end element.
The node between resistance R2 and triode Q3's the collecting electrode directly links to each other with external power source VCC, the node between external power source VCC and the resistance R7 still loops through resistance R8 and R9 ground connection, resistance R9 and electric capacity C3 parallel connection. The node between the resistors R8 and R9 is connected with the base electrode of the triode Q4, the emitting electrodes of the triode Q3 and the Q4 are grounded after sequentially passing through the resistor R11 and the capacitor C4, and the node between the resistor R11 and the capacitor C4 is used as the third end of the whole differential amplifier 1 and is connected with the linear voltage control current source 2. The node between the resistor R2 and the resistor R12 is grounded through a resistor R3, and the resistor R3 is connected with a capacitor C5 in parallel.
The linear voltage-controlled current source 2 comprises an operational amplifier U1, a transistor Q2, resistors R6 and R10. The non-inverting input of the operational amplifier U1 is connected to the controlled voltage VCON as the first terminal of the entire linear voltage-controlled current source 2, and the inverting input is connected to ground through the resistor R6. The non-inverting input of the operational amplifier U1 is also directly connected to ground through a resistor R10. The output end of the operational amplifier U1 is connected to the base of the transistor Q2, the emitter of the transistor Q2 is directly connected to the inverting input end thereof, and the collector of the transistor Q2 is connected to the third end of the differential amplifier 1 as the second end of the whole linear voltage controlled current source 2, specifically, the collector of the transistor Q2 is connected to the node between the resistor R11 and the capacitor C4.
The operation principle of the above-mentioned linear voltage controlled amplifier will be explained as follows:
the amplification factor of the differential amplifier 1 is controlled by the third terminal (i.e. the control terminal) thereof, and the working principle thereof is as follows: when the external load (referring to the back-end component connected to the second end of the differential amplifier 1) and the resistance value of the resistor R7 are equal, for example, 51 Ω, the amplification Av of the differential amplifier 1 is as follows:
the output current ITAIL of the linear voltage controlled amplifier is as follows:
wherein VCON represents a voltage value of the controlled voltage;
the amplification Av of the differential amplifier 1 is therefore as follows:
in the present embodiment, K is a constant:
(other values may be set in other embodiments).
In summary, the amplification factor of the differential amplifier 1 is linearly related to the controlled voltage VCON, so as to realize the linear/linear control characteristic.
In this embodiment, the capacitors C1-C5 are all conventional capacitors, and the capacitance thereof can be set to 0.1 uF.
The resistors R2, R3, R6, R7, R8, R9, R10, R11 and R12 are all conventional common resistors, wherein the resistance value of the resistor R2 is 5.1K Ω, the resistance value of the resistor R3 is 7.5K Ω, the resistance value of the resistor R8 is 5.1K Ω, the resistance value of the resistor R9 is 7.5K Ω, the resistance value of the resistor R12 is 51 Ω, the resistance value of the resistor R7 is 51 Ω, the resistance value of the resistor R11 is 100 Ω, the resistance value of the resistor R6 is 100 Ω, and the resistance value of the resistor R10 is 1K Ω.
The triodes Q2, Q3 and Q4 are all conventional common NPN tubes, and the cut-off frequency fT of the triodes is required to be more than 2 GHz. The operational amplifier U1 is a conventional single voltage supply operational amplifier that is a voltage feedback type operational amplifier.
Please refer to fig. 3 and fig. 4, in which fig. 3 is a control characteristic diagram of the actual measurement result of a linear voltage-controlled amplifier according to the present invention, and fig. 4 is a frequency characteristic diagram of a preferred embodiment of the linear voltage-controlled amplifier according to the present invention. Under the condition that the working temperature is-55-125 ℃, the linear voltage-controlled amplifier disclosed by the invention can normally work when the working voltage is more than 3V, the temperature stability is good, and the working bandwidth can reach 700 MHz.
The linear voltage-controlled amplifier has the advantages of fewer components, small volume and low cost, and the voltage-controlled amplifier can be integrated by an IC (integrated circuit) so as to further reduce the volume. Meanwhile, the voltage-controlled amplifier does not need to be debugged, and is convenient for mass production.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures made by using the contents of the present specification and the drawings can be directly or indirectly applied to other related technical fields, and are within the scope of the present invention.
Claims (9)
1. A linear voltage controlled amplifier comprising: the differential amplifier is connected with the linear voltage control current source, the amplification factor of the differential amplifier is controlled by a third end of the differential amplifier, the third end of the differential amplifier is connected with the output end of the linear voltage control current source, the first end of the differential amplifier is connected with an external input signal, and the second end of the differential amplifier is connected with a rear-end element; the input end of the linear voltage control current source is connected with an external voltage control signal and used for converting the input voltage control signal into output current, the output current and the input voltage control signal are in a linear relation, and the output end of the linear voltage control current source is connected with the third end of the differential amplifier; the amplification factor Av of the differential amplifier is K multiplied by VCON, wherein K is a constant, and VCON represents the voltage value of the controlled voltage; the differential amplifier comprises a first triode, a second triode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a base electrode of the first triode, a collector electrode of the first triode, a emitter electrode of the first triode, an emitter electrode of the second triode, a collector electrode of the second triode, a third resistor, a collector electrode of the second triode, a fourth resistor, a fifth resistor, a sixth resistor, a fifth resistor, a sixth resistor, a fourth resistor, a sixth resistor, a fifth resistor, a fourth resistor, a sixth resistor, a fifth resistor, a fourth resistor, the fifth resistor is connected with the third capacitor in parallel, a node between the fourth resistor and the fifth resistor is connected with a base electrode of the second triode, emitting electrodes of the first triode and the second triode are grounded after sequentially passing through the sixth resistor and the fourth capacitor, the node between the sixth resistor and the fourth capacitor is used as a third end of the whole differential amplifier and is connected with the linear voltage control current source, the node between the first resistor and the seventh resistor is grounded through the second resistor, and the second resistor is connected with the fifth capacitor in parallel.
2. The linear voltage controlled amplifier of claim 1, wherein: the linear voltage control current source comprises an operational amplifier, a third triode, an eighth resistor and a ninth resistor, wherein a positive phase input end of the operational amplifier is used as a first end of the whole linear voltage control current source and is connected with a controlled voltage, a negative phase input end of the operational amplifier is grounded through the eighth resistor, the positive phase input end of the operational amplifier is also directly grounded through the ninth resistor, an output end of the operational amplifier is connected with a base electrode of the third triode, an emitting electrode of the third triode is directly connected with the negative phase input end of the third triode, and a collector electrode is used as a second end of the whole linear voltage control current source and is connected with a third end of the differential amplifier.
3. The linear voltage controlled amplifier of claim 2, wherein: and the collector of the third triode is connected to a node between the sixth resistor and the fourth capacitor.
4. The linear voltage controlled amplifier of claim 2, wherein: the amplification factor Av of the differential amplifier is:wherein R7 represents the resistance value of the third resistor R7, ITAIL represents the output current value of the linear voltage controlled amplifier.
5. The linear voltage controlled amplifier of claim 4, wherein: output current ITAI of the linear voltage controlled amplifierL is:
where VCON represents the voltage value of the controlled voltage and R6 represents the resistance value of the eighth resistor.
6. The linear voltage controlled amplifier of claim 5, wherein: the amplification factor Av of the differential amplifier is: av ═ K × VCON, where
7. The linear voltage controlled amplifier of claim 2, wherein: the first triode, the second triode and the third triode are all NPN tubes, and the cut-off frequency fT of the NPN tubes is required to be larger than 2 GHz.
8. The linear voltage controlled amplifier of claim 2, wherein: the operational amplifier is a single voltage supply operational amplifier.
9. The linear voltage controlled amplifier of claim 8, wherein: the operational amplifier is a voltage feedback operational amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710118756.XA CN106936395B (en) | 2017-03-01 | 2017-03-01 | Linear voltage controlled amplifier |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710118756.XA CN106936395B (en) | 2017-03-01 | 2017-03-01 | Linear voltage controlled amplifier |
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| Publication Number | Publication Date |
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| CN106936395A CN106936395A (en) | 2017-07-07 |
| CN106936395B true CN106936395B (en) | 2020-02-07 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4163950A (en) * | 1978-03-01 | 1979-08-07 | Tektronix, Inc. | Isolating differential amplifier |
| CN101242162A (en) * | 2007-02-08 | 2008-08-13 | 联发科技（新加坡）私人有限公司 | Variable gain amplifying circuit |
| CN102104367A (en) * | 2011-03-04 | 2011-06-22 | 中兴通讯股份有限公司 | Variable gain amplifier (VGA) |
| CN103928842A (en) * | 2014-04-23 | 2014-07-16 | 福建一丁芯光通信科技有限公司 | High-speed laser diode driver integrated circuit adopting negative capacitance neutralizing technology |
-
2017
- 2017-03-01 CN CN201710118756.XA patent/CN106936395B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4163950A (en) * | 1978-03-01 | 1979-08-07 | Tektronix, Inc. | Isolating differential amplifier |
| CN101242162A (en) * | 2007-02-08 | 2008-08-13 | 联发科技（新加坡）私人有限公司 | Variable gain amplifying circuit |
| CN102104367A (en) * | 2011-03-04 | 2011-06-22 | 中兴通讯股份有限公司 | Variable gain amplifier (VGA) |
| CN103928842A (en) * | 2014-04-23 | 2014-07-16 | 福建一丁芯光通信科技有限公司 | High-speed laser diode driver integrated circuit adopting negative capacitance neutralizing technology |
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| CN106936395A (en) | 2017-07-07 |
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