CN113346855B - Large-signal linear amplifying circuit implementation method - Google Patents
Large-signal linear amplifying circuit implementation method Download PDFInfo
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- CN113346855B CN113346855B CN202110517790.0A CN202110517790A CN113346855B CN 113346855 B CN113346855 B CN 113346855B CN 202110517790 A CN202110517790 A CN 202110517790A CN 113346855 B CN113346855 B CN 113346855B
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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
- H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
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Abstract
The application provides a method for realizing a large-signal linear amplifying circuit, and relates to the technical fields of integrated circuit amplifiers, feedback and the like. When the input signal is overlarge and passes through the amplification beyond the output linear amplification area, the feedback circuit can feed back a current signal to the input end so as to reduce the operational amplifier input V of the linear amplification system ep 、V en The signal acts. The feedback form of the application enables the linear amplification system to work in a better linear amplification area all the time.
Description
Technical Field
The application belongs to the technical fields of integrated circuit amplifiers, feedback and the like, and particularly relates to a method for realizing a large-signal linear amplifying circuit.
Background
At present, the integrated circuit has higher and higher integrated level and higher requirements on the performance of the chip. Signal transmission and high quality loss-free transmission are very demanding in terms of system and module requirements. The prior linear amplifier often has distortion line phenomenon when processing large signals.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present application is directed to a linear amplification system that avoids serious signal distortion when processing large signal amplification.
In order to achieve the above objective, the present application provides a method for implementing a large signal linear amplification circuit, in which when an input signal is excessively large and is amplified beyond an output linear amplification region, a feedback circuit feeds back a current signal to an input terminal, so as to achieve the effect of reducing the operational amplification input signal of a linear amplification system.
Further, the traditional circuit diagram of the linear amplification system comprises an input resistor Rin, a resistor Rfb, an amplifier and a feedback device.
Further, the feedback device comprises an adjustable current source and an amplifier.
Further, the linear amplification system relates the outputs (Voutp, voutn) to the op amp inputs (Vep, ven) with a feedback amplifier and voltage controlled current source.
Further, when the input signal is too large, the magnitude of the operational amplifier input ends (Vep, ven) can be adjusted through a feedback system, so that the linear amplification system always works in a linear area.
Further, the method comprises the steps of,
ΔV out ＝(V ep -V en )*A amp
A amp the operational amplifier gain and V of the linear amplifying system ep 、V en Is the signal of the operational amplifier input end after the linear amplifying system passes through the input resistor Rin.
Further, the A is generally described amp Will be very large, the op-amp input will be very small when the linear amplification system is in the linear region, and the output signal of the conventional linear amplification system is limited or enters a nonlinear amplification region due to the fact that the input signal is very large after passing through the linear amplification system, when V ep 、V en Becomes very large and passes through the A amp Harmonic wave and signal distortion can occur later; the feedback system of the application is used for timely feedback adjustment of V when the input signal is overlarge ep 、V en The size is such that the system is always in the linear magnification region.
Further, the feedback system is configured to control the feedback system by correlating the output of the linear amplification system with the input of the linear amplification system amplifier using a variable current source, a feedback network.
Further, when the output signal is relatively large, the variable current source generates a feedback current, and then the feedback current is amplified and fed back to the operational amplifier input end through the feedback network, and finally V is adjusted ep 、V en So that the linear amplification system always operates in the linear amplification region.
Further, the amplification factor n of the feedback network may vary according to a specific design, and the magnitude of n may be 1, 2, 3, … ….
Compared with the prior art, the application has the following beneficial effects: the design is simple and easy to realize, and the design is introduced into the feedback system to ensure that the system is always in a linear amplification area.
Drawings
FIG. 1 is a circuit diagram of a linear amplification circuit in an embodiment of the application;
FIG. 2 is a diagram of a conventional linear amplification circuit in accordance with an embodiment of the present application;
fig. 3 is a feedback circuit diagram in an embodiment of the application.
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
Fig. 2 is a schematic diagram of a conventional linear amplifying circuit, in which a large input signal and a high gain of the amplifying circuit cause the linear amplifier to enter a linear compression region too early due to the limitation of the circuit operating voltage, so that the signal is distorted.
ΔV in ×A＝-ΔV out Equation 1
Equations 1 and 2 are gain calculation formulas of the conventional linear amplification circuit, and can be obtained by them:
a is the feedback system gain.
Equation 3 shown may be such that when the gain is large, the input signal is small if the linear system is to be kept in the linear amplification region. When a large signal is input, distortion (DeltaV) occurs due to the limitation of the operating voltage out And not exceed the chip supply voltage). Due to chip supply voltage limitation DeltaV out Output amplitude, as DeltaV in The gain A of the oversized linear amplification system is kept unchanged, and the signal after being amplified by the linear amplification system exceeds the power supply voltage of the chip and can be limited by amplitude so as to further linearly amplify the systemA nonlinear state is entered. So to have the linear amplifier in the linear amplification region, the input signal must be smaller than
The linear amplification requirement can be met. The proposal of the application is to add a feedback system to the original amplifying system to adjust the signal magnitude V of the input end of the amplifier of the linear amplifying system ep 、V en And further, the problem that the linear amplification system enters a nonlinear state due to overlarge signals is solved.
Fig. 1 and 3 are diagrams of a feedback system according to the present application, including: a circuit and system block diagram. FIG. 2 is a system diagram of the present application, which includes an input resistor Rin, a resistor Rfb, an amplifier, and a feedback device (including an adjustable current source, an amplifier); working principle: when the input signal is oversized and amplified beyond the output linear amplifying region, the feedback circuit will feed back a current signal to the input end to reduce the operational amplifier input V of the linear amplifying system ep 、V en The signal effect (see formula 2) enables the linear amplification system of fig. 1 to operate in a relatively good linear amplification region all the time by this form of feedback.
The feedback principle of fig. 1 is mainly to add a linear amplification system to link the output (Voutp, voutn) with the operational amplifier input ends (Vep, ven) by using a feedback amplifier and a voltage-controlled current source, when the input signal is too large, the magnitude of the operational amplifier input ends Vep, ven can be regulated by the feedback system of the application, so that the linear amplification system always works in a linear area.
ΔV out ＝(V ep -V en )*A amp Equation 4
A amp Operational amplifier gain, V, of a linear amplification system ep 、V en Is the signal of the operational amplifier input end after the linear amplifying system passes through the Rin resistor. General A amp Will be large, V when the linear amplification system is in the linear region ep 、V en Will be small. The traditional linear amplifying system has the advantages that the input signal is greatly amplified by the linear system and the output signal is amplified by the linear systemClipping or entering non-linear amplification region, where V ep 、V en Become very large and pass through operational amplifier A amp Harmonic and signal distortion will occur later. The feedback system of the application is used for timely feedback and regulation of V when the input signal is overlarge ep 、V en The size is such that the system is always in the linear magnification region.
Fig. 3 is a specific implementation of the feedback amplification circuit, MN 1-4, MP 1-2, RI are specific implementations of AMP2 and variable current in fig. 1. The circuit combines the output of the linear amplification system with the input of the linear amplification system amplifier AMP1 by MN 1-4, MP 1-2, RI can form a current source, MN 1-4 forms a feedback network, when the output signal is relatively large, deltaV out 、ΔV e (ΔV e ＝V ep -V en ) MP 1-2, RI generates feedback current I1, I2, then the feedback current I is amplified and fed back to input terminal Ip, in of shipping AMP1 through feedback network, finally V is regulated ep 、V en The linear amplification system always works in the linear amplification region. The feedback network amplification n may vary depending on the particular design, and the magnitude of n may be 1, 2, 3 … ….
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.
Claims (6)
1. When the input signal is overlarge, the size of the operational amplifier input ends (Vep and Ven) is regulated through a feedback system, so that the linear amplifying system always works in a linear area;
the feedback principle of the linear amplification system is that outputs (Voutp, voutn) are connected with Vep, ven by a feedback amplifier and a voltage-controlled current source, when an input signal is overlarge, the magnitudes of the Vep, ven are regulated by the feedback system, so that the linear amplification system always works in a linear region;
ΔV out ＝(V ep -V en )*A amp
A amp operational amplifier gain, V, of a linear amplification system ep 、V en The signal of the operational amplifier input end after the linear amplifying system passes through the Rin resistor; general A amp Large, V when the linear amplification system is in the linear region ep 、V en Will be small; the feedback system is used for timely feeding back and adjusting V when the input signal is overlarge ep 、V en The size, make the system locate at the linear amplifying region all the time;
the feedback circuit is formed by associating the output of the linear amplification system with the input of the linear amplification system amplifier AMP1 by MN 1-4, MP 1-2, RI can form a current source, MN 1-4 forms a feedback network, when the output signal is larger, deltaV out 、ΔV e (ΔV e ＝V ep -V en ) MP 1-2, RI generates feedback current I1, I2, then the feedback current I is amplified and fed back to input terminal Ip, in of shipping AMP1 through feedback network, finally V is regulated ep 、V en The linear amplification system always works in the linear amplification region.
2. The method for implementing a large signal linear amplification circuit according to claim 1, wherein the conventional circuit diagram of the linear amplification system comprises an input resistor Rin, a resistor Rfb, an amplifier and a feedback device.
3. The method of claim 2, wherein the feedback device comprises an adjustable current source and an amplifier.
4. A method of implementing a large signal linear amplification circuit as set forth in claim 3 wherein the feedback system is implemented by associating the output of the linear amplification system with the input of the linear amplification system amplifier using a variable current source, a feedback network.
5. The method of claim 4, wherein when the output signal is relatively large, the variable current source generates a feedback current, and then the feedback current is fed back to the op-amp input terminal through the feedback network and amplified, and finally the V is adjusted ep 、V en So that the linear amplification system always operates in the linear amplification region.
6. The method of claim 5, wherein the amplification factor n of the feedback network is variable according to a specific design.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4591800A (en) * | 1984-10-01 | 1986-05-27 | Motorola, Inc. | Linear power amplifier feedback improvement |
| CN102570989A (en) * | 2010-12-27 | 2012-07-11 | 无锡华润上华半导体有限公司 | Operational amplifier |
| CN207490878U (en) * | 2017-12-29 | 2018-06-12 | 武汉市乔益师电子有限公司 | A kind of amplitude limit low-frequency amplifier circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8823453B2 (en) * | 2012-11-07 | 2014-09-02 | Semtech Corporation | Instrumentation amplifier with rail-to-rail input range |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4591800A (en) * | 1984-10-01 | 1986-05-27 | Motorola, Inc. | Linear power amplifier feedback improvement |
| CN102570989A (en) * | 2010-12-27 | 2012-07-11 | 无锡华润上华半导体有限公司 | Operational amplifier |
| CN207490878U (en) * | 2017-12-29 | 2018-06-12 | 武汉市乔益师电子有限公司 | A kind of amplitude limit low-frequency amplifier circuit |
Non-Patent Citations (2)
| Title |
|---|
| 斩波放大器输出纹波抑制方法综述;张三锋等;《微电子学》;第51卷(第02期);第235-239页 * |
| 福建水产学校.《无线电渔航仪器》.北京：农业出版社,1981,(第1版),第285-291页. * |
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