Multi-channel isolation amplifying circuit

Abstract

The utility model provides a multi-channel isolation amplification circuit which comprises a plurality of isolation amplification branches, and each isolation amplification branch comprises a signal reduction unit, a frequency division isolation module and a signal amplification unit which are sequentially connected between a signal input end and a signal output end; the frequency division isolation module comprises a frequency division unit, a high-frequency signal isolation unit, a low-frequency signal isolation unit and a signal synthesis unit, the high-frequency signal isolation unit and the low-frequency signal isolation unit are connected in parallel between the frequency division unit and the signal synthesis unit, and the input end of the frequency division unit is connected with the output end of the signal reduction unit; the output end of the signal synthesis unit is connected with the input end of the signal amplification unit. Transmission signals are subjected to input impedance matching through the signal reduction unit, the transmission signals are divided into high-frequency components and low-frequency components in the frequency division isolation module, different isolation schemes are adopted respectively, and the broadband signal transmission requirement can be met.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, specifically to a multi-channel isolation amplifier circuit. Background Technology

[0002] In applications involving multi-channel high-speed signal acquisition and processing, signal isolation and amplification are essential technologies.

[0003] Traditional isolation amplifier circuits typically involve trade-offs between the number of channels, isolation performance, and signal bandwidth, making them difficult to meet the demands of high-speed, multi-channel applications. Especially in high-frequency applications, the bandwidth limitations and signal distortion of isolation components (such as standalone optocouplers or transformer-based isolation components) become major bottlenecks. For example, linear optocoupler isolation circuits can achieve very high linearity and isolate DC signals, but their maximum bandwidth is limited to a few MHz, easily causing high-frequency signal distortion. Transformer-based isolation circuits, utilizing the principle of electromagnetic induction, completely isolate the primary and secondary sides, thus isolating the circuit. However, due to the characteristics of electromagnetic induction, transformers cannot isolate DC and low-frequency signals; generally, transformers can only isolate down to the kHz level, easily causing low-frequency signal distortion.

[0004] Therefore, how to achieve high-bandwidth, low-distortion signal isolation transmission has become an urgent technical problem to be solved. Utility Model Content

[0005] This application provides a multi-channel isolation amplifier circuit, which at least solves the technical problem of how to achieve high-bandwidth, low-distortion signal isolation transmission in related technologies.

[0006] According to a first aspect, embodiments of this application provide a multi-channel isolation amplifier circuit, including multiple isolation amplifier branches. Each isolation amplifier branch includes: a signal reduction unit, a frequency division isolation module, and a signal amplification unit connected sequentially between a signal input terminal and a signal output terminal. The frequency division isolation module includes a frequency division unit, a high-frequency signal isolation unit, a low-frequency signal isolation unit, and a signal synthesis unit. The high-frequency signal isolation unit and the low-frequency signal isolation unit are connected in parallel between the frequency division unit and the signal synthesis unit. The input terminal of the frequency division unit is connected to the output terminal of the signal reduction unit, and the output terminal of the signal synthesis unit is connected to the input terminal of the signal amplification unit.

[0007] In one embodiment, the signal reduction unit includes: a first operational amplifier, a first input resistor, and a first feedback resistor, wherein the signal input terminal is connected to the first input terminal of the first operational amplifier through the first input resistor, the second input terminal of the first operational amplifier is grounded, the output terminal of the first operational amplifier is connected to the first input terminal through the first feedback resistor, and the output terminal of the first operational amplifier is connected to the input terminal of the frequency divider unit, and the resistance value of the first feedback resistor is less than the resistance value of the first input resistor.

[0008] In one embodiment, the signal amplification unit includes: a second operational amplifier, a second input resistor, and a second feedback resistor, wherein the output terminal of the signal synthesis unit is connected to the first input terminal of the second operational amplifier through the second input resistor, the second input terminal of the second operational amplifier is grounded, the output terminal of the second operational amplifier is connected to the first input terminal through the second feedback resistor, and the output terminal of the second operational amplifier is connected to the signal output terminal, and the resistance value of the second feedback resistor is greater than the resistance value of the second input resistor.

[0009] In one embodiment, the signal amplification unit further includes a bias circuit connected to the second input terminal of the second operational amplifier for zero-bias adjustment of the transmitted signal.

[0010] In one embodiment, the signal amplification unit further includes a filter circuit connected between the output of the second operational amplifier and ground, for suppressing high-frequency noise and clutter.

[0011] In one embodiment, the frequency divider circuit includes a high-frequency branch and a low-frequency branch, wherein the low-frequency branch includes a low-pass filter circuit, and the high-frequency branch includes a subtraction circuit; the input terminal of the low-pass filter circuit is connected to the output terminal of the signal reduction unit; the output terminal of the low-pass filter circuit is connected to the first input terminal of the subtraction circuit, and the second input terminal of the subtraction circuit is connected to the output terminal of the signal reduction unit.

[0012] In one embodiment, the high-frequency signal isolation unit includes a transformer, one end of the primary winding of the transformer is connected to the output terminal of the high-frequency branch, and the other end is grounded; one end of the secondary winding is connected to the first input terminal of the signal synthesis unit, and the other end is grounded.

[0013] In one embodiment, the low-frequency signal isolation unit includes an optocoupler circuit, the input terminal of which is connected to the output terminal of the low-frequency branch, and the output terminal of which is connected to the second input terminal of the signal synthesis unit.

[0014] In one embodiment, the signal synthesis unit includes an adder circuit, the first input terminal of which is connected to the output terminal of the high-frequency signal isolation unit, and the second input terminal of which is connected to the output terminal of the low-frequency signal isolation unit.

[0015] In one embodiment, the multi-channel isolation amplifier circuit further includes an isolation power supply module having isolation power supply circuits corresponding one-to-one with the isolation amplifier branches.

[0016] This application has at least the following beneficial effects:

[0017] The multi-channel isolation amplifier circuit in this application includes multiple isolation amplifier branches. Each isolation amplifier branch includes: a signal reduction unit, a frequency division isolation module, and a signal amplification unit connected sequentially between the signal input terminal and the signal output terminal. The frequency division isolation module includes a frequency division unit, a high-frequency signal isolation unit, a low-frequency signal isolation unit, and a signal synthesis unit. The high-frequency signal isolation unit and the low-frequency signal isolation unit are connected in parallel between the frequency division unit and the signal synthesis unit. The input terminal of the frequency division unit is connected to the output terminal of the signal reduction unit, and the output terminal of the signal synthesis unit is connected to the input terminal of the signal amplification unit. The transmitted signal undergoes input impedance matching and amplitude range adjustment via a signal reduction unit. After passing through a frequency division and isolation module, the transmitted signal is restored to its original amplitude. This process achieves impedance matching, amplitude adjustment, and signal recovery, ensuring stable transmission across different amplitude ranges. Good input-output impedance matching reduces signal distortion. During transmission within the frequency division and isolation module, the signal is divided into high-frequency and low-frequency components. The low-frequency component is isolated by a low-frequency signal isolation unit, ensuring high linearity and low distortion in the low-frequency portion. Simultaneously, the high-frequency component is isolated by a high-frequency signal isolation unit and then reconstructed by a signal synthesis unit, further separating the transmitted signal into high-frequency and low-frequency components. Different isolation schemes are employed for each component, ensuring optimal isolation for both types of signals. Therefore, this method can meet the requirements of broadband signal transmission. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a modular structure of an exemplary multi-channel isolation amplifier circuit according to an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the circuit principle of a signal reduction unit and a signal amplification unit of an exemplary multi-channel isolation amplifier circuit according to an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the circuit principle of the frequency division isolation module of a multi-channel isolation amplifier circuit according to one embodiment of this application;

[0023] Figure 4 This is a schematic diagram of the circuit principle of the isolation power supply unit of a multi-channel isolation amplifier circuit according to one embodiment of this application. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, including a series of units, systems, products, or devices is not necessarily limited to those explicitly listed, but may include units, systems, products, or devices not explicitly listed.

[0026] This application provides a multi-channel isolation amplifier circuit, including multiple isolation amplifier branches, see [link to relevant documentation]. Figure 1 As shown, each isolated amplification branch includes:

[0027] A signal reduction unit 20, a frequency division isolation module 30, and a signal amplification unit 40 are sequentially connected between the signal input terminal 10 and the signal output terminal 50. The signal reduction unit 20 adjusts the input impedance of the transmitted signal and reduces its amplitude to ensure it is within the range required by the isolation unit. After isolation by the frequency division isolation module 30, the transmitted signal enters the signal amplification unit 40 to restore it to its original amplitude.

[0028] The frequency division isolation module 30 includes a frequency division unit 31, a high-frequency signal isolation unit 32, a low-frequency signal isolation unit 33, and a signal synthesis unit 34. The high-frequency signal isolation unit 32 and the low-frequency signal isolation unit 33 are connected in parallel between the frequency division unit 31 and the signal synthesis unit 34. The input terminal of the frequency division unit 31 is connected to the output terminal of the signal reduction unit 20, and the output terminal of the signal synthesis unit 34 is connected to the input terminal of the signal amplification unit 40.

[0029] In this embodiment, the transmitted signal undergoes input impedance matching and amplitude range adjustment via the signal reduction unit 20. After passing through the frequency division isolation module 30, the transmitted signal is restored to its original amplitude, achieving impedance matching, amplitude adjustment, and signal recovery. This ensures stable transmission of the transmitted signal within different amplitude ranges, good input-output impedance matching, and reduced signal distortion. When the transmitted signal enters the frequency division isolation module 30, it is divided into high-frequency and low-frequency components by the frequency division unit 31. The low-frequency component is isolated by the low-frequency signal isolation unit 33, ensuring high linearity and low distortion in the low-frequency portion. Simultaneously, the high-frequency component is isolated by the high-frequency signal isolation unit 32 and then reconstructed by the signal synthesis unit 34, dividing the transmitted signal into high-frequency and low-frequency components. Different corresponding isolation schemes are used for each component, ensuring optimal isolation for both high-frequency and low-frequency signals. Therefore, this method can meet the requirements of broadband signal transmission.

[0030] In one embodiment, the signal reduction unit 20 includes: a first operational amplifier 21, a first input resistor R1, and a first feedback resistor Rf1, wherein the signal input terminal 10 is connected to the first input terminal of the first operational amplifier 21 through the first input resistor R1, the second input terminal of the first operational amplifier 21 is grounded, the output terminal of the first operational amplifier 21 is connected to the first input terminal through the first feedback resistor Rf1, and the output terminal of the first operational amplifier 21 is connected to the input terminal of the frequency division unit 31, and the resistance value of the first feedback resistor Rf1 is less than the resistance value of the first input resistor R1.

[0031] In this embodiment, the signal reduction unit 20 is an amplification circuit constructed by the first operational amplifier 21, wherein the resistance value of the first feedback resistor Rf1 is less than the resistance value of the first input resistor R1 to achieve signal reduction. It can be a non-inverting amplifier circuit or an inverting amplifier circuit; in this embodiment, an inverting amplifier circuit is used as an example for explanation.

[0032] The first input resistor R1 is connected to the inverting input terminal of the first operational amplifier 21, and the first feedback resistor Rf1 is connected between the output terminal and the inverting input terminal of the first operational amplifier 21. The amplification factor of the first operational amplifier 21 is: -Rf1 f1 / R1, where R f1 Rf1 is the resistance value of the first feedback resistor, and R1 is the resistance value of the first input resistor R1.

[0033] In one embodiment, the signal amplification unit 40 includes: a second operational amplifier 41, a second input resistor R2, and a second feedback resistor Rf2. The output terminal of the frequency division isolation module 30 is connected to the first input terminal of the second operational amplifier 41 through the second input resistor R2. The second input terminal of the second operational amplifier 41 is grounded. The output terminal of the second operational amplifier 41 is connected to the first input terminal through the second feedback resistor Rf2. The output terminal of the second operational amplifier 41 is also connected to the signal output terminal 50. The resistance value of the second feedback resistor Rf2 is greater than the resistance value of the second input resistor R2.

[0034] In this embodiment, the signal amplification unit 40 is an amplification circuit constructed using the second operational amplifier 41. The resistance value of the second feedback resistor Rf2 is greater than the resistance value of the second input resistor R2 to achieve signal amplification. Both in-phase and out-of-phase amplification can be used. In this embodiment, the same amplification circuit as the signal reduction circuit is used to ensure that the signal output by the signal amplification unit 40 is in phase with the input signal of the signal reduction unit 20. In this embodiment, an out-of-phase amplification circuit is used as an example for explanation.

[0035] The second input resistor R2 is connected to the inverting input terminal of the second operational amplifier 41, and the second feedback resistor Rf2 is connected between the output terminal and the inverting input terminal of the second operational amplifier 41. The amplification factor of the second operational amplifier 41 is: -Rf2. f2 / R2, where R f2 Rf2 is the resistance value of the second feedback resistor, and R2 is the resistance value of the second input resistor R2.

[0036] The signal amplification unit 40 further includes a bias circuit 42 connected to the second input terminal of the second operational amplifier 41, used for zero-bias adjustment of the signal. In this embodiment, the bias circuit 42 can be connected to the power supply or ground via a potentiometer connected in series with a fixed resistor. The center tap of the potentiometer is connected to the second input terminal of the second operational amplifier 41. By adjusting the potentiometer, the DC bias of the input signal is changed, thereby adjusting the zero bias of the signal.

[0037] The signal amplification unit 40 further includes a filter circuit 43 connected between the output terminal of the second operational amplifier 41 and ground, used to suppress high-frequency noise and clutter. In this embodiment, an RC filter circuit composed of resistors and filter capacitors can be used to suppress high-frequency noise and clutter in the signal.

[0038] In this embodiment, the transmitted signal is conditioned by the signal amplification unit 20 and the signal reduction unit 40, resulting in good input-output impedance matching, low signal transmission distortion, and adjustable signal amplification and reduction rates by changing the values ​​of the input resistor and feedback resistor to adapt to different input signal ranges. Furthermore, it can support bandwidths higher than 50MHz, meeting the requirements for high-speed signal transmission.

[0039] In one embodiment, the frequency division unit 31 includes a high-frequency branch 312 and a low-frequency branch 311, wherein the low-frequency branch 311 includes a low-pass filter circuit, and the high-frequency branch 312 includes a subtraction circuit; the input terminal of the low-pass filter circuit is connected to the output terminal of the signal reduction unit 20; the output terminal of the low-pass filter circuit is connected to the first input terminal of the subtraction circuit, and the second input terminal of the subtraction circuit is connected to the output terminal of the signal reduction unit 20.

[0040] In this embodiment, the low-pass filter circuit can adopt either a Sallen-Key circuit topology or an MFB topology. The low-frequency component in the transmitted signal is obtained through the low-pass filter circuit and then transmitted to the low-frequency signal isolation unit 33 for isolated transmission.

[0041] The subtraction circuit can be constructed using an operational amplifier. Its non-inverting input is connected to the output of the signal reduction unit 20 via a resistor, receiving the transmitted signal output by the signal reduction unit 20. Its inverting input is connected to the output of the low-pass filter circuit via a resistor, and the output of the subtraction circuit is connected to the inverting input via a feedback resistor. The subtraction circuit can be a differential amplifier with a 1:1 amplification ratio. The low-frequency component and the transmitted signal output from the signal reduction unit 20 are input to the subtractor for subtraction. The low-frequency component of the complete transmitted signal is subtracted from the signal at the output of the subtraction circuit, and the remaining high-frequency component is transmitted to the high-frequency signal isolation unit 32 for isolated transmission.

[0042] In one embodiment, the high-frequency signal isolation unit 32 includes a transformer. One end of the primary winding of the transformer is connected to the output terminal of the high-frequency branch 312, and the other end is grounded. One end of the secondary winding is connected to the first input terminal of the signal synthesis unit 34, and the other end is grounded. In this embodiment, a high-frequency isolation transformer is used to achieve complete transmission of high-frequency signals through a push-pull drive circuit.

[0043] The low-frequency signal isolation unit 33 includes an optocoupler circuit. The input terminal of the optocoupler circuit is connected to the output terminal of the low-frequency branch 311, and the output terminal of the optocoupler circuit is connected to the second input terminal of the signal synthesis unit 34. In this embodiment, a linear optocoupler is used for low-frequency signal isolation, and the optocoupler design ensures high linearity and low distortion.

[0044] In one embodiment, the signal synthesis unit 34 includes an adder circuit. The first input terminal of the adder circuit is connected to the output terminal of the high-frequency signal isolation unit 32, and the second input terminal of the adder circuit is connected to the output terminal of the low-frequency signal isolation unit 33. The output terminal of the adder circuit is connected to the inverting input terminal via a feedback resistor. The adder circuit can be a differential amplifier with a 1:1 amplification ratio, used to superimpose high-frequency and low-frequency components to achieve reconstructed output of the transmitted signal.

[0045] In this embodiment, the high-frequency channel bandwidth of the frequency division isolation module 30 can reach over 50MHz, with low-frequency signal distortion. By combining optocouplers and transformers, it adapts to wideband signal transmission requirements. It features high isolation withstand voltage, meeting industrial and medical application standards.

[0046] In one embodiment, the multi-channel isolation amplifier circuit further includes an isolation power supply module 60, having isolation power supply circuits corresponding one-to-one with the isolation amplifier branches. In this embodiment, the isolation power supply circuit may include a front-stage power supply isolation circuit 61 and a rear-stage power supply isolation circuit 62. The front-stage power supply isolation circuit 61 can power the signal reduction unit 20, frequency division unit 31, and other front-stage circuits, while the rear-stage power supply isolation circuit 62 can power the signal amplification unit 40, signal synthesis unit 34, and other rear-stage circuits. In this embodiment, the isolation power supply circuit can use a DC-DC isolation module for isolation, with each channel powered by an independent isolation power supply unit, ensuring complete isolation between the front and rear stages of signal transmission. This module is designed to avoid electrical interference between channels while providing stable power supply to ensure the accuracy of signal transmission. In this embodiment, the isolation power supply unit has a high isolation withstand voltage (≥2500Vrms) to ensure electrical isolation safety, meeting the high requirements of multi-channel systems for power supply stability.

[0047] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0048] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A multi-channel isolation amplifier circuit, comprising multiple isolation amplifier branches, characterized in that, Each isolated amplification branch includes: A signal reduction unit, a frequency division isolation module, and a signal amplification unit are connected sequentially between the signal input terminal and the signal output terminal; The frequency division isolation module includes a frequency division unit, a high-frequency signal isolation unit, a low-frequency signal isolation unit, and a signal synthesis unit. The high-frequency signal isolation unit and the low-frequency signal isolation unit are connected in parallel between the frequency division unit and the signal synthesis unit. The input terminal of the frequency division unit is connected to the output terminal of the signal reduction unit, and the output terminal of the signal synthesis unit is connected to the input terminal of the signal amplification unit.

2. The multi-channel isolation amplifier circuit as described in claim 1, characterized in that, The signal reduction unit includes a first operational amplifier, a first input resistor, and a first feedback resistor. The signal input terminal is connected to the first input terminal of the first operational amplifier through the first input resistor. The second input terminal of the first operational amplifier is grounded. The output terminal of the first operational amplifier is connected to the first input terminal through the first feedback resistor. The output terminal of the first operational amplifier is also connected to the input terminal of the frequency division unit. The resistance value of the first feedback resistor is less than the resistance value of the first input resistor.

3. The multi-channel isolation amplifier circuit as described in claim 1, characterized in that, The signal amplification unit includes a second operational amplifier, a second input resistor, and a second feedback resistor. The output terminal of the signal synthesis unit is connected to the first input terminal of the second operational amplifier through the second input resistor. The second input terminal of the second operational amplifier is grounded. The output terminal of the second operational amplifier is connected to the first input terminal through the second feedback resistor, and the output terminal of the second operational amplifier is connected to the signal output terminal. The resistance value of the second feedback resistor is greater than the resistance value of the second input resistor.

4. The multi-channel isolation amplifier circuit as described in claim 3, characterized in that, The signal amplification unit also includes a bias circuit connected to the second input terminal of the second operational amplifier, used for zero-bias adjustment of the transmitted signal.

5. The multi-channel isolation amplifier circuit as described in claim 3, characterized in that, The signal amplification unit also includes a filter circuit connected between the output of the second operational amplifier and ground, used to suppress high-frequency noise and spurious signals.

6. The multi-channel isolation amplifier circuit as described in claim 1, characterized in that, The frequency division unit includes: a high-frequency branch and a low-frequency branch. The low-frequency branch includes a low-pass filter circuit, and the high-frequency branch includes a subtraction circuit. The input terminal of the low-pass filter circuit is connected to the output terminal of the signal reduction unit; the output terminal of the low-pass filter circuit is connected to the first input terminal of the subtraction circuit, and the second input terminal of the subtraction circuit is connected to the output terminal of the signal reduction unit.

7. The multi-channel isolation amplifier circuit as described in claim 6, characterized in that, The high-frequency signal isolation unit includes a transformer. One end of the primary winding of the transformer is connected to the output terminal of the high-frequency branch, and the other end is grounded. One end of the secondary winding is connected to the first input terminal of the signal synthesis unit, and the other end is grounded.

8. The multi-channel isolation amplifier circuit as described in claim 7, characterized in that, The low-frequency signal isolation unit includes an optocoupler circuit, the input terminal of which is connected to the output terminal of the low-frequency branch, and the output terminal of which is connected to the second input terminal of the signal synthesis unit.

9. The multi-channel isolation amplifier circuit as described in claim 1, characterized in that, The signal synthesis unit includes an adder circuit, the first input terminal of which is connected to the output terminal of the high-frequency signal isolation unit, and the second input terminal of which is connected to the output terminal of the low-frequency signal isolation unit.

10. The multi-channel isolation amplifier circuit as described in claim 1, characterized in that, Also includes: The isolated power supply module has an isolated power supply circuit that corresponds one-to-one with the isolated amplification branch.

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