CN204498074U - A kind of direct-current coupling differential amplifying device - Google Patents
A kind of direct-current coupling differential amplifying device Download PDFInfo
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- CN204498074U CN204498074U CN201520320442.4U CN201520320442U CN204498074U CN 204498074 U CN204498074 U CN 204498074U CN 201520320442 U CN201520320442 U CN 201520320442U CN 204498074 U CN204498074 U CN 204498074U
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Abstract
The utility model proposes a kind of direct-current coupling differential amplifying device, comprising: difference filter comprises differential mode filter and common-mode filter; Protection module comprises: the first and second Schottky double diodes; Difference ratio amplification module comprises; First and second operational amplifiers, wherein, the positive input of the first operational amplifier is connected to the first Schottky double diode, and the positive input of the second operational amplifier is connected to the second Schottky double diode; Compensating resistance module comprises: the first and second compensating resistances, and wherein, the first compensating resistance is connected with the output of the first operational amplifier, and the second compensating resistance is connected with the second operational amplifier.The utility model employing difference filter can suppress the common mode interference signal in Signal transmissions better, makes signal transmission distance farther, and can realize the amplification to direct current and AC signal simultaneously.
Description
Technical field
The utility model relates to electronic circuit technology field, particularly a kind of direct-current coupling differential amplifying device.
Background technology
In signals collecting, usually adopt common single-ended amplifier to amplify signal, the defect of this amplification mode is:
(1) can not common mode disturbances be suppressed, affect signal transmission distance;
(2) because the input at amplifying circuit is provided with capacitance, this amplifying circuit only can be amplified AC signal, and the amplification to direct current signal and AC signal cannot be realized simultaneously.
Utility model content
The purpose of this utility model is intended at least solve one of described technological deficiency.
For this reason, the purpose of this utility model is to propose a kind of direct-current coupling differential amplifying device, can suppress the common mode interference signal in Signal transmissions better, make signal transmission distance farther.
To achieve these goals, the utility model embodiment on the one hand provides a kind of direct-current coupling differential amplifying device, comprise: difference filter, protection module, difference ratio amplification module and compensating resistance module, wherein, described difference filter comprises differential mode filter and common-mode filter, wherein, described common-mode filter comprises: the first and second resistance, first and second electric capacity, wherein, one end of described first electric capacity is connected with described first resistance, other end ground connection, one end of described second electric capacity is connected with described second resistance, other end ground connection, described differential mode filter comprises: the 3rd electric capacity, one end of described 3rd electric capacity is connected with one end of described first electric capacity, the other end of described 3rd electric capacity is connected with one end of described second electric capacity, described protection module comprises: the first Schottky double diode and the second Schottky double diode, described difference ratio amplification module comprises, first and second operational amplifiers, wherein, the positive input of described first operational amplifier is connected to described first Schottky double diode, and the positive input of described second operational amplifier is connected to described second Schottky double diode, described compensating resistance module comprises: the first and second compensating resistances, and wherein, described first compensating resistance is connected with the output of described first operational amplifier, and described second compensating resistance is connected with described second operational amplifier.
In an embodiment of the present utility model, also comprise: the first low pass filter, between the negative input that described first low pass filter is connected to described first operational amplifier and output, wherein, described first low pass filter comprises: the 3rd resistance be connected in parallel and the 4th electric capacity; Second low pass filter, between the negative input that described second low pass filter is connected to described second operational amplifier and output, wherein, described second low pass filter comprises: the 4th resistance be connected in parallel and the 5th electric capacity.
In another embodiment of the present utility model, also comprise: the 5th resistance, described 5th resistance is connected between the negative input of described first operational amplifier and the negative input of described second operational amplifier.
According to the direct-current coupling differential amplifying device of the utility model embodiment, employing difference filter can suppress the common mode interference signal in Signal transmissions better, makes signal transmission distance farther.Further, the utility model does not arrange capacitance at the input of amplifying circuit, thus can realize the amplification to direct current and AC signal simultaneously.
The aspect that the utility model is additional and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present utility model.
Accompanying drawing explanation
Above-mentioned and/or additional aspect of the present utility model and advantage will become obvious and easy understand from accompanying drawing below combining to the description of embodiment, wherein:
Fig. 1 is the circuit diagram of the direct-current coupling differential amplifying device according to the utility model embodiment.
Embodiment
Be described below in detail embodiment of the present utility model, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the utility model, and can not be interpreted as restriction of the present utility model.
In the utility model, unless otherwise clearly defined and limited, the term such as term " installation ", " being connected ", " connection ", " fixing " should be interpreted broadly, and such as, can be fixedly connected with, also can be removably connect, or connect integratedly; Can be mechanical connection, also can be electrical connection; Can be directly be connected, also indirectly can be connected by intermediary, can be the connection of two element internals.For the ordinary skill in the art, the concrete meaning of above-mentioned term in the utility model can be understood as the case may be.
The utility model provides a kind of direct-current coupling differential amplifier circuit applied in signals collecting, can realize the amplification to direct current and AC signal simultaneously.
As shown in Figure 1, the direct-current coupling differential amplifying device of the utility model embodiment comprises: difference filter 1, protection module 2, difference ratio amplification module 3 and compensating resistance module 4.
Particularly, difference filter 1 comprises: differential mode filter and common-mode filter.Wherein, common-mode filter comprises: the first resistance R1, the second resistance R2, the first electric capacity C1 and the second electric capacity C2.Wherein, one end of the first electric capacity C1 is connected with the first resistance R1, other end ground connection AGND.One end of second electric capacity C2 is connected with the second resistance R2, other end ground connection AGND.Wherein, the first resistance R1 and the second resistance R2, as compensating resistance, may be used for reducing or eliminate stray inductance and amplifier input capacitance in transmission line and easily forms the vibration that LC resonant circuit produces.
Differential mode filter comprises: the 3rd electric capacity C3, and wherein one end of the 3rd electric capacity C3 is connected with one end of the first electric capacity C1, and the other end of the 3rd electric capacity C3 is connected with the second electric capacity C2.Wherein, the capacitance of the first electric capacity C1 and the second electric capacity C2 is 300pF, and the capacitance of the 3rd electric capacity C3 is 3nF.
Protection module 2 comprises the first Schottky double diode D1 and the second Schottky double diode D2.In an embodiment of the present utility model, the model of the first and second Schottky double diodes can be BAT54S.
Difference ratio amplification module 3 comprises: the first operational amplifier U1A and the second operational amplifier U1B.Wherein, the positive input of the first operational amplifier U1A is connected to the first Schottky double diode D1, and the positive input of the first operational amplifier U1B is connected to the first Schottky double diode D2.Particularly; first and second Schottky double diodes are added in the input of the first and second operational amplifiers as protection device, can prevent static discharge and input voltage from exceeding the maximum input voltage scope of operational amplifier and damaging the first and second operational amplifiers.
Compensating resistance module 4 comprises the first compensating resistance R6 and the second compensating resistance R7.Wherein, the first compensating resistance R6 is connected with the output of the first operational amplifier U1A, and the second compensating resistance R7 is connected with the second operational amplifier U1A.Particularly, first compensating resistance R6 can carry out compensating in ring to the first operational amplifier U1A, increase the ability that the first operational amplifier U1A is with capacitive load, second compensating resistance R7 can carry out compensating in ring to the second operational amplifier U1B, increases the ability that the second operational amplifier U1B is with capacitive load.
In an embodiment of the present utility model, direct-current coupling differential amplifying device of the present utility model also comprises: the first and second low pass filters, for suppressing the noise of the first operational amplifier U1A and the second operational amplifier U1B respectively.Wherein, between the negative input that the first low pass filter is connected to the first operational amplifier U1A and output, wherein, the first low pass filter comprises: the 3rd resistance R3 be connected in parallel and the 4th electric capacity C4.Between the negative input that second low pass filter is connected to the second operational amplifier U1B and output.Wherein, the second low pass filter comprises: the 4th resistance R5 be connected in parallel and the 5th electric capacity C5.
Further, direct-current coupling differential amplifying device of the present utility model also comprises: the 5th resistance R4, and wherein, the 5th resistance R4 is connected between the negative input of the first operational amplifier U1A and the negative input of the second operational amplifier U1B.
Below the Input output Relationship of direct-current coupling differential amplifying device of the present utility model is described:
The output signal VTP7=(VTP5-VTP6) of the first operational amplifier U1A. (1+R3/R4)+VTP6.
The output signal VTP8=(VTP6-VTP5) of the second operational amplifier U1B. (1+R5/R4)+VTP5.
Disconnected short with void from void:
VTP1＝VTP3＝VTP5；
VTP2＝VTP4＝VTP6。
The major parameter of circuit can be obtained thus:
The differential amplification multiple of the first operational amplifier U1A and the second operational amplifier U1B:
A＝(R3+R4+R5)/R4；
The cut-off frequency of differential mode filter:
fd＝1/2π(Rd+R1+R2)(C3+CS12)；
The cut-off frequency of common-mode filter:
fc＝1/2π(Rc+R1)C1＝1/2π(RC+R2)C2；
Wherein, Rd is transducer differential-mode output impedance, and Rc is common mode output impedance, and the series equivalent capacitance of C1 and C2 is CS12.
According to the direct-current coupling differential amplifying device of the utility model embodiment, employing difference filter can suppress the common mode interference signal in Signal transmissions better, makes signal transmission distance farther.Further, the utility model does not arrange capacitance at the input of amplifying circuit, thus can realize the amplification to direct current and AC signal simultaneously.
In the description of this specification, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present utility model or example.In this manual, identical embodiment or example are not necessarily referred to the schematic representation of above-mentioned term.And the specific features of description, structure, material or feature can combine in an appropriate manner in any one or more embodiment or example.
Although illustrate and described embodiment of the present utility model above, be understandable that, above-described embodiment is exemplary, can not be interpreted as restriction of the present utility model, those of ordinary skill in the art can change above-described embodiment when not departing from principle of the present utility model and aim, revising, replacing and modification in scope of the present utility model.Scope of the present utility model is by claims extremely equivalency.
Claims (3)
1. a direct-current coupling differential amplifying device, is characterized in that, comprising: difference filter, protection module, difference ratio amplification module and compensating resistance module, wherein,
Described difference filter comprises differential mode filter and common-mode filter, wherein,
Described common-mode filter comprises: the first and second resistance, the first and second electric capacity, and wherein, one end of described first electric capacity is connected with described first resistance, other end ground connection, and one end of described second electric capacity is connected with described second resistance, other end ground connection,
Described differential mode filter comprises: the 3rd electric capacity, and one end of described 3rd electric capacity is connected with one end of described first electric capacity, and the other end of described 3rd electric capacity is connected with one end of described second electric capacity;
Described protection module comprises: the first Schottky double diode and the second Schottky double diode;
Described difference ratio amplification module comprises; First and second operational amplifiers, wherein, the positive input of described first operational amplifier is connected to described first Schottky double diode, and the positive input of described second operational amplifier is connected to described second Schottky double diode;
Described compensating resistance module comprises: the first and second compensating resistances, and wherein, described first compensating resistance is connected with the output of described first operational amplifier, and described second compensating resistance is connected with described second operational amplifier.
2. direct-current coupling differential amplifying device as claimed in claim 1, is characterized in that, also comprise:
First low pass filter, between the negative input that described first low pass filter is connected to described first operational amplifier and output, wherein, described first low pass filter comprises: the 3rd resistance be connected in parallel and the 4th electric capacity;
Second low pass filter, between the negative input that described second low pass filter is connected to described second operational amplifier and output, wherein, described second low pass filter comprises: the 4th resistance be connected in parallel and the 5th electric capacity.
3. direct-current coupling differential amplifying device as claimed in claim 2, it is characterized in that, also comprise: the 5th resistance, described 5th resistance is connected between the negative input of described first operational amplifier and the negative input of described second operational amplifier.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520320442.4U CN204498074U (en) | 2015-05-18 | 2015-05-18 | A kind of direct-current coupling differential amplifying device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201520320442.4U CN204498074U (en) | 2015-05-18 | 2015-05-18 | A kind of direct-current coupling differential amplifying device |
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| CN204498074U true CN204498074U (en) | 2015-07-22 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111937284A (en) * | 2018-02-15 | 2020-11-13 | Tdk电子股份有限公司 | Compensation filter and method for starting up a compensation filter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111937284A (en) * | 2018-02-15 | 2020-11-13 | Tdk电子股份有限公司 | Compensation filter and method for starting up a compensation filter |
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Granted publication date: 20150722 |