CN103269203A - Biasing circuit of operational amplifier - Google Patents
Biasing circuit of operational amplifier Download PDFInfo
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- CN103269203A CN103269203A CN201310221346XA CN201310221346A CN103269203A CN 103269203 A CN103269203 A CN 103269203A CN 201310221346X A CN201310221346X A CN 201310221346XA CN 201310221346 A CN201310221346 A CN 201310221346A CN 103269203 A CN103269203 A CN 103269203A
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Abstract
The invention discloses a biasing circuit of an operational amplifier. The biasing circuit of the operational amplifier comprises the operational amplifier, a power supply end is grounded through a capacitor C1, a grounding end is grounded, a normal-phase input terminal is grounded through a resistor R3 and is connected with an input signal INPUT, an inverting input terminal is grounded through a resistor R1, an output terminal is connected back to the inverting input terminal through a resistor R2, and the resistor R2 and the resistor R1 form negative voltage feedback. According to the biasing circuit of the operational amplifier, the leak current from the positive input terminal of the operational amplifier flows through the resistor R3, a biasing voltage which is supplied to the operational amplifier is generated, the leak current is an intrinsic parameter of the operational amplifier and does not change as outer conditions change, and therefore the biasing voltage supplied by the resistor R3 is stable and unchanged so that the operational amplifier works stably.
Description
Technical field
The present invention relates to the operation amplifier circuit technical field, relate in particular to a kind of operational amplifier biasing circuit.
Background technology
Operational amplifier is to be integrated in a crystal amplifier on the chip, and operational amplifier comprises power end usually, earth terminal, and normal phase input end, inverting input and output, power end connect filter capacitor over the ground, earth terminal ground connection.Wherein the normal phase input end of operational amplifier and inverting input have the leakage current of different sizes according to the operational amplifier different model.And an essential condition of operational amplifier steady operation is bias voltage.When bias voltage refers to that transistor is in magnifying state, between base stage and the emitter, the voltage that should arrange between collector electrode and the base stage.Because make transistor be in magnifying state, the PN junction between its base stage and the emitter should positively biased, and the PN junction between collector electrode and the base stage is anti-inclined to one side.Positively biased or anti-inclined to one side voltage are bias voltage, and the PN junction positively biased between transistor base and the emitter is set, and the anti-inclined to one side circuit of the PN junction between collector electrode and the base stage abbreviates biasing circuit as.
The method that provides of the bias voltage that operational amplifier is commonly used has electric resistance partial pressure and voltage follower.Wherein the electric resistance partial pressure mode is that circuit design is simple for operational amplifier provides the advantage of bias voltage, and weak point is that output voltage changes with load variations, changes with mains voltage variations.Though and the biasing circuit of voltage follower mode has solved the problem that output voltage changes with load variations, fail to solve the problem that changes with mains voltage variations.
Summary of the invention
The object of the present invention is to provide a kind of operational amplifier biasing circuit, being intended to solve the leakage current that how to utilize the operational amplifier input provides the problem of bias voltage for it.
For solving the problems of the technologies described above, technical scheme of the present invention is: a kind of operational amplifier biasing circuit comprises operational amplifier, and described power end is through capacitor C 1 ground connection, earth terminal ground connection, and described normal phase input end is through resistance R 3 ground connection, and meets input signal INPUT; Described inverting input is through resistance R 1 ground connection; Described output takes back described inverting input through resistance R 2, and described resistance R 2 forms the voltage negative feedback with described resistance R 1.
As further improvement, the two ends of described resistance R 2 also connect capacitor C 2, and described parallel resistor R2 and capacitor C 2 form the voltage negative feedback with described resistance R 1.
As further improvement, described input signal inserts described normal phase input end through capacitor C 4.
After adopting technique scheme, the invention has the beneficial effects as follows: because operational amplifier biasing circuit of the present invention comprises operational amplifier, wherein normal phase input end is through resistance R 3 ground connection, because the normal phase input end of operational amplifier has bigger leakage current, this leakage current is flowed through after the resistance R 3, produce a voltage at normal phase input end, this voltage provides a bias voltage for operational amplifier.Because leakage current is the parameter of operational amplifier inside, behind selected operational amplifier, leakage current big or small constant, after the resistance of definite R3, this bias voltage is stablized constant as required.Stable bias voltage makes the operational amplifier working stability.
Description of drawings
Fig. 1 is the circuit diagram of the embodiment of the invention one;
Fig. 2 is the circuit diagram of the embodiment of the invention two;
Among the figure: 1-output, 2-inverting input, 3-normal phase input end, 4-earth terminal, 8-power end.
Embodiment
In order to make purpose of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explaining the present invention, and be not used in restriction the present invention.
Embodiment one:
As shown in Figure 1, a kind of operational amplifier biasing circuit comprises operational amplifier U7-A, and wherein power end 8 is through capacitor C 1 ground connection, earth terminal 4 ground connection, and wherein normal phase input end 3 is through resistance R 3 ground connection, and meets input signal INPUT; Wherein anti-phase input 2 ends are through resistance R 1 ground connection; Wherein the output signal OUTPUT of output 1 takes back described inverting input 2 through parallel resistor R2 and capacitor C 2, and this parallel resistor R2 and capacitor C 2 form the voltage negative feedback.
Wherein normal phase input end is through resistance R 3 ground connection, because inverting input 2 and the normal phase input end 3 of operational amplifier have leakage current, the leakage current difference of the operational amplifier of different model, tens pA that have, the hundreds of that a has nA.For the bigger amplifier of leakage current, when leakage current flows through this resistance R 3, produce a voltage at normal phase input end 3, this voltage provides a bias voltage for operational amplifier.The resistance of R3 will be determined according to the size of leakage current.Because leakage current is the parameter of operational amplifier, do not change with external factor such as load and supply voltages, behind selected operational amplifier, a stable bias voltage is provided can for this operational amplifier.
Wherein the parallel resistor R2 of output 1 connection forms the voltage negative feedback with the resistance R 1 that capacitor C 2 is connected with anti-phase input 2 ends.Along with the frequency of input signal INPUT constantly increases, the equiva lent impedance of the parallel circuits of R2 and C2 constantly reduces, and the closed loop multiplication factor of this operational amplifier also constantly reduces.The effect of above-mentioned capacitor C 2 is the multiplication factors that suppress high-frequency signal, and frequency is more high, and the ability of inhibition is more strong.
Embodiment two:
As shown in Figure 2, basic identical with embodiment one, difference is: the input signal INPUT of this operational amplifier inserts normal phase input end through a capacitor C 4.Coupling capacitance between these capacitor C 4 conducts and the previous stage amplifier, this capacitor C 4 forms a high-pass filtering circuit with resistance R 3 simultaneously.Realized the amplifying power of operational amplifier to input signal INPUT, operational amplifier possesses low-pass characteristic.
The above preferred embodiment of the present invention not in order to limiting the present invention, all any modifications of doing within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. an operational amplifier biasing circuit comprises operational amplifier, and described operational amplifier comprises power end, earth terminal, and normal phase input end, inverting input and output, described power end meets filter capacitor C1 over the ground, and described earth terminal ground connection is characterized in that:
Described normal phase input end is through resistance R 3 ground connection, and meets input signal INPUT;
Described inverting input is through resistance R 1 ground connection;
Described output takes back described inverting input through resistance R 2, and described resistance R 2 forms the voltage negative feedback with described resistance R 1.
2. operational amplifier biasing circuit according to claim 1, it is characterized in that: the two ends of described resistance R 2 also connect capacitor C 2, and described resistance R 2 in parallel and capacitor C 2 form the voltage negative feedback with described resistance R 1.
3. operational amplifier biasing circuit according to claim 1 and 2, it is characterized in that: described input signal INPUT is through electric capacity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310221346XA CN103269203A (en) | 2013-06-05 | 2013-06-05 | Biasing circuit of operational amplifier |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310221346XA CN103269203A (en) | 2013-06-05 | 2013-06-05 | Biasing circuit of operational amplifier |
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| CN103269203A true CN103269203A (en) | 2013-08-28 |
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| CN201310221346XA Pending CN103269203A (en) | 2013-06-05 | 2013-06-05 | Biasing circuit of operational amplifier |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103701416A (en) * | 2013-12-31 | 2014-04-02 | 青岛歌尔声学科技有限公司 | Infrared signal amplifying circuit |
| CN104092921B (en) * | 2014-07-14 | 2017-06-16 | 中国兵器工业集团第二一四研究所苏州研发中心 | Multi-channel video signal transacting hydrid integrated circuit |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1287398A (en) * | 1999-10-27 | 2001-03-14 | 深圳市中兴通讯股份有限公司 | Full-load range precise current-equalizing device |
| CN101115328A (en) * | 2006-07-25 | 2008-01-30 | 三洋电机株式会社 | microphone amplifier |
| CN101285857A (en) * | 2008-05-26 | 2008-10-15 | 中国航天科技集团公司第五研究院第五一四研究所 | AC current-voltage converter and device and method for measuring small AC current |
| CN101349716A (en) * | 2008-07-22 | 2009-01-21 | 上海海事大学 | Micro capacitance reference measurement circuit |
| CN102035500A (en) * | 2009-10-01 | 2011-04-27 | 邓加慧 | High anti-interference high-pass amplifier |
-
2013
- 2013-06-05 CN CN201310221346XA patent/CN103269203A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1287398A (en) * | 1999-10-27 | 2001-03-14 | 深圳市中兴通讯股份有限公司 | Full-load range precise current-equalizing device |
| CN101115328A (en) * | 2006-07-25 | 2008-01-30 | 三洋电机株式会社 | microphone amplifier |
| CN101285857A (en) * | 2008-05-26 | 2008-10-15 | 中国航天科技集团公司第五研究院第五一四研究所 | AC current-voltage converter and device and method for measuring small AC current |
| CN101349716A (en) * | 2008-07-22 | 2009-01-21 | 上海海事大学 | Micro capacitance reference measurement circuit |
| CN102035500A (en) * | 2009-10-01 | 2011-04-27 | 邓加慧 | High anti-interference high-pass amplifier |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103701416A (en) * | 2013-12-31 | 2014-04-02 | 青岛歌尔声学科技有限公司 | Infrared signal amplifying circuit |
| CN104092921B (en) * | 2014-07-14 | 2017-06-16 | 中国兵器工业集团第二一四研究所苏州研发中心 | Multi-channel video signal transacting hydrid integrated circuit |
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Application publication date: 20130828 |