CN111969994A - Broadband analog signal isolation transmission circuit based on magnetic field coupling - Google Patents
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
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Abstract
The invention discloses a magnetic field coupling-based broadband analog signal isolation transmission circuit which comprises an isolation transformer, an isolation end high-resistance amplifier and a non-isolation end high-resistance amplifier, wherein a primary winding and a tertiary winding are arranged on the primary side of the isolation transformer, a secondary winding is arranged on the secondary side of the isolation transformer, the primary winding and the tertiary winding are both connected with the isolation end high-resistance amplifier, and the secondary winding is connected with the non-isolation end high-resistance amplifier. The output signal of the whole isolation circuit is equal to the input signal of the whole isolation circuit, so that the isolation of the original signal is realized, and when a transformer capable of covering a higher frequency band is selected, the amplitude-frequency characteristic response of low-frequency band analog signal isolation transmission can be ensured while the isolation of the high-frequency band signal of the transformer is improved only by adding a capacitor or a resistor to reduce the turning frequency point of two first-order RC high-pass filter circuits.
Description
Technical Field
The invention relates to the field of isolated transmission of analog signals, in particular to a broadband analog signal isolated transmission circuit based on magnetic field coupling.
Background
The isolated transmission of analog signals of current isolation oscilloscopes is generally accomplished by utilizing magnetic field coupling realized by a transformer. A transformer consists essentially of two windings wound on a common core. When an alternating voltage is applied to one winding, an alternating voltage is induced to the other winding due to electromagnetic induction. Therefore, the windings of the transformer are mutually connected through the alternating magnetic field so as to complete the transmission of the alternating signal, and the isolated end and the non-isolated end are mutually isolated on the circuit. A schematic diagram of a transformer implemented wideband analog signal isolation transmission circuit is shown in fig. 1.
The transformer realizes the isolated transmission of analog signals, and the dielectric strength of the isolation depends on the insulating strength between windings and between the windings and the ground. The magnetic field coupling can usually realize the isolated transmission of analog signals between 100KHz and 500MHz, and because of the structural characteristics of the transformer, the number of turns is reduced to reduce the distributed capacitance and the number of turns is reduced to seriously influence the amplitude-frequency characteristic of a low frequency band when the isolated transmission of signals with the frequency of more than 500MHz is expanded, thereby causing a contradiction, so that one transformer can only isolate a certain section of high-frequency signals, such as an isolation transformer TC1-1T, and the frequency response of the transformer is between 400KHz and 500 MHz; and the frequency response of the same series of TC4-14 is between 200MHz and 1400 MHz. Therefore, if isolated transmission of broadband analog signals between 400KHz and 1400MHz is to be realized, two transformers are used, and the higher the upper limit frequency of the broadband signals to be isolated is, the more transformers are needed. At this time, the signal is divided into multiple paths for transmission, which not only greatly increases the volume, but also increases the signal noise and affects the signal quality.
Disclosure of Invention
Aiming at the problems of the existing broadband analog signal isolation transmission circuit, the invention provides a broadband analog signal isolation transmission circuit based on magnetic field coupling, which can expand the isolation transmission capability of high-frequency band analog signals and simultaneously ensure the corresponding amplitude-frequency characteristic of low-frequency band analog signal isolation transmission.
The invention adopts the following technical scheme:
a broadband analog signal isolation transmission circuit based on magnetic field coupling comprises an isolation transformer, an isolation end high-resistance amplifier and a non-isolation end high-resistance amplifier, wherein a primary winding and a tertiary winding are arranged on a primary side of the isolation transformer, a secondary winding is arranged on a secondary side of the isolation transformer, the primary winding and the tertiary winding are both connected with the isolation end high-resistance amplifier, and the secondary winding is connected with the non-isolation end high-resistance amplifier.
Preferably, the secondary winding and the tertiary winding have the same number of turns and distribution parameters.
Preferably, one end of the primary winding is grounded, and the other end of the primary winding is connected with the output end of the isolation end high-resistance amplifier;
one end of the tertiary winding is grounded, and the other end of the tertiary winding is connected with a first high-pass filter circuit which is connected with the reverse input end of the isolation end high-resistance amplifier;
the positive input end of the isolation end high-resistance amplifier is connected with an input signal.
Preferably, one end of the secondary winding is grounded, and the other end of the secondary winding is connected with a second high-pass filter circuit which is connected with the positive input end of the non-isolation end high-resistance amplifier;
the output end of the non-isolation end high-resistance amplifier is connected with the reverse input end of the non-isolation end high-resistance amplifier.
Preferably, the first high-pass filter circuit and the second high-pass filter circuit are both first-order RC high-pass filter circuits, the first high-pass filter circuit includes a first capacitor and a first resistor, the first capacitor is connected in series with the first resistor, and the first resistor is grounded;
the third winding is connected with the first capacitor, and the reverse input end of the isolation end high-resistance amplifier is connected between the first capacitor and the first resistor;
the second high-pass filter circuit comprises a second capacitor and a second resistor, the second capacitor is connected with the second resistor in series, and the second resistor is grounded;
the secondary winding is connected with the second capacitor, and the positive input end of the non-isolation end high-resistance amplifier is connected between the second capacitor and the second resistor.
Preferably, the first capacitor is identical to the second capacitor, and the first resistor is identical to the second resistor.
The invention has the beneficial effects that:
the input signal of the whole isolation circuit is equal to the output signal of the first high-pass filter circuit driven by the tertiary winding, and the tertiary winding and the secondary winding have the same number of turns and distribution parameters, so that the output of the secondary winding is the same as that of the tertiary winding, and the output of the first-order RC high-pass filter circuit driven by the secondary winding and having the same parameters is also the same; since the non-isolation end high-resistance amplifier is connected into a voltage follower mode, the output signal of the whole isolation circuit is equal to the output signal of the second high-pass filter circuit driven by the secondary winding. In summary, the output signal of the whole isolation circuit is equal to the input signal of the whole isolation circuit, so that the isolation of the original signal is realized, and when a transformer capable of covering a higher frequency band is selected, the frequency band of the low-frequency band analog signal can be greatly expanded only by increasing the capacitance or increasing the resistance to reduce the turning frequency point of the two first-order RC high-pass filter circuits, and the flatness of the amplitude-frequency characteristic response can be greatly ensured.
The invention expands the isolation transmission capability of high-frequency band and low-frequency band analog signals, can solve the contradiction caused by the structural characteristics of the transformer, can improve the isolation of the high-frequency band signals of the transformer, and can ensure the amplitude-frequency characteristic response of the low-frequency band analog signal isolation transmission.
Drawings
Fig. 1 is a schematic block diagram of a prior art wideband analog signal isolation circuit.
Fig. 2 is a schematic block diagram of a broadband analog signal isolation circuit based on magnetic field coupling.
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:
with reference to fig. 2, a magnetic field coupling-based broadband analog signal isolation transmission circuit includes an isolation transformer, an isolation-side high-impedance amplifier N1, and a non-isolation-side high-impedance amplifier N2.
The input resistance of a high-resistance amplifier is typically higher than 109Ω, the high-resistance amplifier has little effect on the input signal.
The primary side of the isolation transformer is provided with a primary winding 1 and a tertiary winding 2, the secondary side of the isolation transformer is provided with a secondary winding 3, the primary winding and the tertiary winding are both connected with the isolation end high-resistance amplifier, and the secondary winding is connected with the non-isolation end high-resistance amplifier.
The high-frequency-band analog signal isolation transmission capability can be further expanded, and the key of ensuring the amplitude-frequency characteristic response of low-frequency-band analog signal isolation transmission is the tertiary winding for feeding back a signal path.
Specifically, the secondary winding and the tertiary winding have the same number of turns and distribution parameters, so that the tertiary winding and the secondary winding have the same characteristic output response.
The primary winding and the tertiary winding also have the same number of turns and distribution parameters.
One end of the primary winding is grounded, and the other end of the primary winding is connected with the output end of the isolation end high-resistance amplifier N1.
One end of the tertiary winding is grounded, the other end of the tertiary winding is connected with a first high-pass filter circuit, and the first high-pass filter circuit is connected with the reverse input end of the isolation end high-resistance amplifier and serves as a feedback path.
The positive input end of the isolation end high-resistance amplifier is connected with an input signal Ui.
One end of the secondary winding is grounded, the other end of the secondary winding is connected with a second high-pass filter circuit, and the second high-pass filter circuit is connected with the positive input end of the non-isolation end high-resistance amplifier.
The output end of the non-isolation end high-resistance amplifier is connected with the reverse input end of the non-isolation end high-resistance amplifier to form a voltage follower mode. The output Uo of the non-isolated high-impedance amplifier is the output of the whole isolation circuit.
Specifically, the first high-pass filter circuit and the second high-pass filter circuit are both first-order RC high-pass filter circuits, the first high-pass filter circuit includes a first capacitor C1 and a first resistor R1, the first capacitor is connected in series with the first resistor, and the first resistor is grounded.
The third winding is connected with the first capacitor, and the reverse input end of the isolation end high-resistance amplifier is connected between the first capacitor and the first resistor.
The second high-pass filter circuit comprises a second capacitor C2 and a second resistor R2, wherein the second capacitor is connected with the second resistor in series, and the second resistor is grounded.
The secondary winding is connected with the second capacitor, and the positive input end of the non-isolation end high-resistance amplifier is connected between the second capacitor and the second resistor.
The first capacitor is the same as the second capacitor, and the first resistor is the same as the second resistor. I.e. the first high-pass filter circuit and the second high-pass filter circuit have the same parameters.
When the isolation end high-resistance amplifier N1 and the non-isolation end high-resistance amplifier N2 work in a deep negative feedback state, the isolation end high-resistance amplifier N1 and the non-isolation end high-resistance amplifier N2 have the characteristics of 'virtual short' and 'virtual disconnection', so that although the positive and negative input ends of the two high-resistance amplifiers are in the 'virtual disconnection' state, almost no current passes through the positive and negative input ends, signals of the two output ends can be regarded as 'virtual short', and the two output ends are in a:
an input signal Ui of the whole isolation circuit is equal to an output signal of a first high-pass filter circuit driven by a tertiary winding;
because the tertiary winding and the secondary winding have the same number of turns and distribution parameters, the output of the secondary winding is the same as that of the tertiary winding, and the output of a first-order RC high-pass filter circuit with the same parameters driven by the tertiary winding and the secondary winding is also the same;
since the non-isolated terminal high-resistance amplifier is connected into a voltage follower mode, the output signal Uo of the whole isolation circuit is equal to the output signal of the second high-pass filter circuit driven by the secondary winding.
In summary, the output signal Uo of the whole isolation circuit is equal to the input signal Ui of the whole isolation circuit, so that the isolation of the original signal is realized, and when a transformer capable of covering a higher frequency band is selected, due to the existence of a feedback path, the frequency band of the low-frequency band analog signal can be greatly expanded only by reducing the turning frequency point of the two first-order RC high-pass filter circuits by adding a capacitor or a resistor, and the flatness of the amplitude-frequency characteristic response can be greatly ensured.
And the turning frequency of the first-order RC high-pass filters with the same parameters is adjusted, so that the signal isolation transmission capability of a low frequency band can be ensured while the number of turns of the isolation transformer is reduced and the signal isolation transmission capability of a high frequency band is expanded.
The invention expands the isolation transmission capability of high-frequency band and low-frequency band analog signals, can solve the contradiction caused by the structural characteristics of the transformer, can improve the isolation of the high-frequency band signals of the transformer, and can ensure the amplitude-frequency characteristic response of the low-frequency band analog signal isolation transmission.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (6)
1. A broadband analog signal isolation transmission circuit based on magnetic field coupling is characterized by comprising an isolation transformer, an isolation end high-resistance amplifier and a non-isolation end high-resistance amplifier, wherein a primary winding and a tertiary winding are arranged on the primary side of the isolation transformer, a secondary winding is arranged on the secondary side of the isolation transformer, the primary winding and the tertiary winding are both connected with the isolation end high-resistance amplifier, and the secondary winding is connected with the non-isolation end high-resistance amplifier.
2. The magnetic field coupling-based broadband analog signal isolation transmission circuit according to claim 1, wherein the secondary winding and the tertiary winding have the same number of turns and distribution parameters.
3. The magnetic field coupling-based broadband analog signal isolation transmission circuit according to claim 1, wherein one end of the primary winding is grounded, and the other end of the primary winding is connected with the output end of the isolation-end high-resistance amplifier;
one end of the tertiary winding is grounded, and the other end of the tertiary winding is connected with a first high-pass filter circuit which is connected with the reverse input end of the isolation end high-resistance amplifier;
the positive input end of the isolation end high-resistance amplifier is connected with an input signal.
4. The magnetic field coupling-based broadband analog signal isolation transmission circuit according to claim 3, wherein one end of the secondary winding is grounded, and the other end of the secondary winding is connected with a second high-pass filter circuit which is connected with a positive input end of a non-isolation end high-resistance amplifier;
the output end of the non-isolation end high-resistance amplifier is connected with the reverse input end of the non-isolation end high-resistance amplifier.
5. The magnetic field coupling-based broadband analog signal isolation transmission circuit according to claim 4, wherein the first high-pass filter circuit and the second high-pass filter circuit are both first-order RC high-pass filter circuits, the first high-pass filter circuit comprises a first capacitor and a first resistor, the first capacitor is connected with the first resistor in series, and the first resistor is grounded;
the third winding is connected with the first capacitor, and the reverse input end of the isolation end high-resistance amplifier is connected between the first capacitor and the first resistor;
the second high-pass filter circuit comprises a second capacitor and a second resistor, the second capacitor is connected with the second resistor in series, and the second resistor is grounded;
the secondary winding is connected with the second capacitor, and the positive input end of the non-isolation end high-resistance amplifier is connected between the second capacitor and the second resistor.
6. The magnetic field coupling-based broadband analog signal isolation transmission circuit according to claim 5, wherein the first capacitor is the same as the second capacitor, and the first resistor is the same as the second resistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010769990.0A CN111969994A (en) | 2020-08-04 | 2020-08-04 | Broadband analog signal isolation transmission circuit based on magnetic field coupling |
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| CN202010769990.0A CN111969994A (en) | 2020-08-04 | 2020-08-04 | Broadband analog signal isolation transmission circuit based on magnetic field coupling |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112653447A (en) * | 2020-12-16 | 2021-04-13 | 北京航天计量测试技术研究所 | Analog signal isolation circuit based on transformer |
Citations (7)
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|---|---|---|---|---|
| US5517154A (en) * | 1995-01-13 | 1996-05-14 | Tektronix, Inc. | Split-path linear isolation circuit apparatus and method |
| CN201355808Y (en) * | 2009-02-11 | 2009-12-02 | 张兴杰 | High bandwidth linear isolation module |
| CN103733493A (en) * | 2011-08-12 | 2014-04-16 | 萨甘安全防护公司 | AC/DC converter with galvanic insulation and signal corrector |
| CN204539119U (en) * | 2015-05-21 | 2015-08-05 | 北京联合大学 | A kind of electric signal sampling isolation circuit |
| CN108134600A (en) * | 2018-02-12 | 2018-06-08 | 中山市嘉科电子有限公司 | A kind of switching signal isolation circuit |
| CN111082799A (en) * | 2019-12-25 | 2020-04-28 | 广州金升阳科技有限公司 | Signal isolation transmission circuit |
| CN111262573A (en) * | 2020-03-23 | 2020-06-09 | 常州信息职业技术学院 | Miniaturized low-conduction delay digital signal isolation transmission system |
-
2020
- 2020-08-04 CN CN202010769990.0A patent/CN111969994A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5517154A (en) * | 1995-01-13 | 1996-05-14 | Tektronix, Inc. | Split-path linear isolation circuit apparatus and method |
| CN201355808Y (en) * | 2009-02-11 | 2009-12-02 | 张兴杰 | High bandwidth linear isolation module |
| CN103733493A (en) * | 2011-08-12 | 2014-04-16 | 萨甘安全防护公司 | AC/DC converter with galvanic insulation and signal corrector |
| CN204539119U (en) * | 2015-05-21 | 2015-08-05 | 北京联合大学 | A kind of electric signal sampling isolation circuit |
| CN108134600A (en) * | 2018-02-12 | 2018-06-08 | 中山市嘉科电子有限公司 | A kind of switching signal isolation circuit |
| CN111082799A (en) * | 2019-12-25 | 2020-04-28 | 广州金升阳科技有限公司 | Signal isolation transmission circuit |
| CN111262573A (en) * | 2020-03-23 | 2020-06-09 | 常州信息职业技术学院 | Miniaturized low-conduction delay digital signal isolation transmission system |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112653447A (en) * | 2020-12-16 | 2021-04-13 | 北京航天计量测试技术研究所 | Analog signal isolation circuit based on transformer |
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Application publication date: 20201120 |