Extremely low frequency wideband signal amplification circuit

Abstract

The utility model relates to a kind of very low frequency broadband signal amplification circuit, belong to electronic circuit technical field. Very low frequency broadband signal amplification circuit includes two-stage filter circuit and three-stage amplifier circuit. First-stage filter circuit connects signal input end, for the filtering processing of very low frequency signal, and the very low frequency signal is the underwater acoustic signal of frequency as low as 0.001 hertz;The input end of first-stage amplifier circuit is connected with the output end of first-stage filter circuit;The input end of second-stage amplifier circuit is connected with the output end of first-stage amplifier circuit;Second-stage filter circuit connects the output end of second-stage amplifier circuit;The input end of third-stage amplifier circuit is connected with the output end of second-stage filter circuit;Negative feedback low-pass filter circuit is connected to the input end of first-stage amplifier circuit through the output end of third-stage amplifier circuit;The output end of third-stage amplifier circuit is as the output end of very low frequency broadband signal amplification circuit.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to an ultra-low noise, high input impedance, ultra-low frequency broadband signal amplifier circuit. Background Technology

[0002] Marine hydrophones are used for the identification of marine acoustic signals.

[0003] Sound waves of various frequencies propagate in the ocean, including high-frequency, mid-frequency, and low-frequency sound waves, as well as extremely low-frequency sound waves with frequencies below 0.001 Hz. Extremely low-frequency sound waves have extremely low frequencies and periods ranging from tens to hundreds of seconds. The signal processing circuit of an extremely low-frequency piezoelectric hydrophone not only needs high input impedance to extend its low-frequency characteristics, but also must consider the severe impact of 1 / f flicker noise in the low-frequency range.

[0004] In existing technologies, in order to improve the ability to identify low-frequency signals in the ocean, a preamplifier is usually designed to preprocess the underwater acoustic signals.

[0005] For example, a high input impedance integrated operational amplifier can be used for signal amplification. It can achieve an input impedance of up to 6 GΩ at an operating frequency of 0.01 Hz, and the amplifier's operating frequency range is 0.01 Hz to 100 kHz. This solution takes into account the high input impedance matching requirements, but the integrated operational amplifier used has a high 1 / f noise problem, which makes it difficult to meet the low noise detection requirements of weak acoustic signals.

[0006] Alternatively, a combination of multiple amplifier circuits can be used to solve the problem of identifying extremely low frequency acoustic signals. However, this can lead to performance issues between the multiple amplifier stages. Utility Model Content

[0007] This invention at least partially solves one of the technical problems in related technologies, providing an ultra-low noise, high input impedance, ultra-low frequency broadband signal amplifier circuit.

[0008] To achieve the above objectives, in a first aspect, this utility model provides an ultra-low noise, high input impedance, ultra-low frequency broadband signal amplifier circuit, comprising:

[0009] First-stage filter circuit: connected to the signal input terminal, used for filtering extremely low frequency signals, the extremely low frequency signals being underwater acoustic signals with a frequency as low as 0.001 Hz;

[0010] The first-stage amplifier circuit: its input terminal is connected to the output terminal of the first filter circuit;

[0011] The second-stage amplifier circuit: its input terminal is connected to the output terminal of the first-stage amplifier circuit;

[0012] The second-stage filter circuit: its input terminal is connected to the output terminal of the second-stage amplifier circuit;

[0013] The third-stage amplifier circuit: its input terminal is connected to the output terminal of the second-stage filter circuit;

[0014] Negative feedback low-pass filter circuit: The output of the third-stage amplifier circuit is connected to the input of the first-stage amplifier circuit;

[0015] The output terminal of the third-stage amplifier circuit serves as the output terminal of the ultra-low frequency broadband signal amplifier circuit.

[0016] In some embodiments of this application, the first-stage amplifier circuit includes a field-effect transistor, whose gate is connected to the output terminal of the first-stage filter circuit; whose source is connected to the negative feedback low-pass filter circuit and the negative input terminal of the second-stage amplifier circuit; and whose drain is connected to the input terminal of the second-stage amplifier circuit.

[0017] In some embodiments of this application, the second-stage amplifier circuit includes a PNP transistor, whose emitter is connected to the system positive power supply via a resistor, whose base is connected to the drain of the field-effect transistor of the first-stage amplifier circuit, and whose collector is connected to the system ground via a resistor and connected to the second-stage filter circuit.

[0018] In some embodiments of this application, a resistor is connected in series in the circuit between the collector of the PNP transistor and the source of the effect transistor.

[0019] In some embodiments of this application, a resistor is connected in series in the circuit between the emitter of the PNP transistor and the drain of the effect transistor.

[0020] In some embodiments of this application, the second-stage filter circuit is used for filtering extremely low-frequency signals with frequencies as low as 0.001 Hz. It includes a capacitor and a resistor connected in series. The capacitor end is connected to the output of the second-stage amplifier circuit, the resistor end is connected to system ground, and the capacitor and resistor connection end is connected to the positive input of the third-stage amplifier circuit.

[0021] In some embodiments of this application, the third-stage amplifier circuit includes an amplifier, the negative input terminal of which is grounded through a resistor and connected to the output terminal through a resistor; the positive input terminal is connected to the output terminal of the second-stage filter circuit; and the output terminal is connected to a signal output interface.

[0022] In some embodiments of this application, the output of the amplifier is connected to the source of the field-effect transistor in the first-stage amplifier circuit via a negative feedback low-pass filter circuit.

[0023] In some embodiments of this application, the first-stage filter circuit and the second-stage filter circuit are RC filter circuits.

[0024] To address the need for detecting extremely low-frequency weak acoustic signals, an ultra-low-noise, high-input-impedance ultra-low-frequency broadband signal amplification circuit was designed. Compared to existing technologies, the ultra-low-frequency signal amplification circuit provided in this application has at least the following advantages:

[0025] 1. The ultra-low frequency signal amplification circuit provided in this application is a three-stage amplifier circuit in series. This circuit is a low-noise, high-input-impedance amplifier circuit with a negative feedback low-pass filter circuit, which is suitable for the identification of extremely low noise weak signals.

[0026] 2. The first-stage amplifier circuit uses a common-source amplifier circuit composed of an ultra-low frequency high-pass filter and an ultra-low noise JFET to achieve high input impedance for ultra-low frequency AC signals; the second-stage amplifier circuit uses a PNP common-emitter amplifier circuit to achieve inversion of the amplified signal and low output impedance; the third-stage amplifier circuit uses an ultra-low frequency high-pass filter and a non-inverting proportional low-noise integrated operational amplifier circuit to achieve DC component removal and high-gain AC amplification of the second-stage amplified output signal.

[0027] 3. The negative feedback low-pass filter circuit feeds the output signal of the third-stage amplifier circuit back to the first-stage amplifier circuit. The negative feedback amplification of the three-stage amplifier circuit is achieved through the voltage series negative feedback low-pass filter circuit, which improves the stability of the circuit.

[0028] The above description is merely an overview of the technical solution disclosed herein. In order to better understand the technical means of this disclosure and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this disclosure more apparent and understandable, specific embodiments of this disclosure are described below. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a circuit block diagram of an ultra-low frequency broadband signal amplification circuit according to an embodiment of this application;

[0031] Figure 2 This is a circuit schematic diagram of an ultra-low frequency broadband signal amplifier circuit according to an embodiment of this application;

[0032] Figure 3 This is an amplitude-frequency characteristic curve of an ultra-low frequency broadband signal amplifier circuit according to an embodiment of this application;

[0033] Figure 4This is a phase frequency response curve of an ultra-low frequency broadband signal amplifier circuit according to an embodiment of this application. Detailed Implementation

[0034] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0035] The prefixes such as "first" and "second" used in this application embodiment are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not constitute unnecessary restrictions due to the use of such prefixes. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0036] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; the term "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0037] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0038] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0039] Extremely low frequency (ELF) signals typically have low amplitude and are easily drowned out by noise. This is especially true in underwater communication, such as underwater acoustic communication, where the frequency of the acoustic signal is low and the underwater environment is noisy. Amplification circuits are usually needed to amplify the received weak acoustic signal so that it can be accurately decoded, thereby achieving reliable underwater communication.

[0040] To address the above problems, this application proposes an ultra-low noise, high input impedance, ultra-low frequency broadband signal amplifier circuit, the specific circuit block diagram of which is shown below. Figure 1 As shown, the circuit schematic is as follows: Figure 2 As shown, it specifically includes a three-stage amplifier and a negative feedback low-pass filter circuit.

[0041] In summary, the ultra-low noise, high input impedance, ultra-low frequency signal amplifier circuit includes:

[0042] First-stage filter circuit: connected to the signal input terminal, used for filtering extremely low frequency signals, which are underwater acoustic signals with frequencies as low as 0.001 Hz;

[0043] The first-stage amplifier circuit: its input terminal is connected to the output terminal of the first filter circuit;

[0044] The second-stage amplifier circuit: its input terminal is connected to the output terminal of the first-stage amplifier circuit;

[0045] The second-stage filter circuit: its input terminal is connected to the output terminal of the second-stage amplifier circuit;

[0046] The third-stage amplifier circuit: its input terminal is connected to the output terminal of the second-stage amplifier circuit;

[0047] Negative feedback low-pass filter circuit: The output of the third-stage amplifier circuit is connected to the input of the first-stage amplifier circuit;

[0048] The output of the third-stage amplifier circuit serves as the output of the ultra-low frequency broadband signal amplifier circuit.

[0049] Based on the ultra-low noise, high input impedance ultra-low frequency signal amplification circuit provided in the embodiments of this application, the ultra-low noise, high input impedance ultra-low frequency broadband signal amplification circuit can effectively amplify these ultra-low frequency signals while suppressing noise and improving the signal transmission quality.

[0050] It should be understood that underwater acoustic signals with frequencies as low as 0.001 Hz refer to underwater acoustic signals with frequencies greater than 0.001 Hz that can be amplified and identified by the ultra-low frequency broadband signal amplifier circuit proposed in this application.

[0051] In some embodiments of this application, the first filtering circuit is an RC filtering circuit, including a filtering resistor R1 and a filtering capacitor C1. The first terminal of the filtering capacitor C1 is connected to the signal input terminal, the second terminal of the filtering capacitor C1 is connected to the first terminal of the filtering resistor R1 and connected to the first-stage amplifier circuit, and the second terminal of the filtering resistor R1 is connected to the signal input terminal.

[0052] For details, please refer to the following: Figure 1 The input terminal of the first filter circuit serves as the signal input terminal, which can be connected to the signal output of devices such as piezoelectric acoustic transducers. After passing through the RC ultra-low frequency high-pass filter circuit, by reasonably setting the values ​​of capacitors and resistors, low-frequency signals are filtered, causing signals with frequencies below 0.001Hz to be significantly attenuated, thus setting the lower cutoff frequency of the circuit.

[0053] In some embodiments of this application, the first-stage amplifier circuit includes a field-effect transistor Q1, whose gate is connected to the output terminal of the first filter circuit, specifically to the second terminal of the filter capacitor C1; its source is connected to the negative feedback low-pass filter circuit and the negative input terminal of the second-stage amplifier circuit; and its drain is connected to the positive input terminal of the second-stage amplifier circuit.

[0054] It should be understood that, in order to amplify extremely low frequency signals, the first-stage amplifier circuit uses a common-source amplifier circuit composed of an extremely low frequency high-pass filter and an ultra-low noise JFET to enable the input of extremely low frequency AC signals with high input impedance.

[0055] In some embodiments of this application, the second-stage amplifier circuit includes a PNP transistor Q2. The PNP common-emitter amplifier circuit realizes the inversion of the amplified signal and low output impedance output. The emitter of the PNP transistor Q2 is connected to the drain of the field-effect transistor of the first-stage amplifier circuit through a resistor. Its emitter is connected to the positive power supply of the system through a resistor. Its base is connected to the drain of the field-effect transistor of the first-stage amplifier circuit. Its collector is connected to the source of the field-effect transistor of the first-stage amplifier circuit through a resistor and connected to the second-stage filter circuit.

[0056] In some embodiments of this application, a resistor R2 is connected in series in the circuit between the collector of the PNP transistor Q2 and the source of the effect transistor. The resistor R2 is a high-impedance resistor.

[0057] In some embodiments of this application, a resistor R3 is connected in series in the circuit between the emitter of the PNP transistor Q2 and the drain of the effect transistor. Resistor R3 is a high-impedance resistor.

[0058] By employing a high-impedance design, the impedance matching characteristics of the circuit can be further optimized, ensuring smoother signal transmission between different amplification stages and improving the overall gain stability of the amplifier circuit. The use of high-impedance resistors can also suppress noise generation to some extent, thereby improving the signal-to-noise ratio of the amplifier circuit and making the amplified signal clearer and more accurate, suitable for subsequent processing and analysis. Based on the above structure, the amplifier circuit of this application can achieve high gain, low noise, high input impedance, and low output impedance characteristics during the amplification of extremely low-frequency signals, thus meeting the needs of various high-precision signal processing applications.

[0059] The second-stage filter circuit is used for filtering extremely low-frequency signals down to 0.001 Hz. The circuit parameters are the same as those of the first-stage filter circuit, including a capacitor and a resistor connected in series. The capacitor is connected to the output of the second-stage amplifier circuit, the resistor is connected to the system ground, and the capacitor and resistor connection is connected to the positive input of the third-stage amplifier circuit.

[0060] The third-stage amplifier circuit includes an amplifier, whose negative input terminal is grounded through a resistor and connected to the output terminal through another resistor; the positive input terminal is connected to the output terminal of the second-stage filter circuit; and the output terminal is connected to the signal output interface.

[0061] Specifically, the third-stage amplifier circuit uses a non-inverting, low-noise integrated operational amplifier circuit to achieve high-gain AC amplification of the second-stage amplified output signal.

[0062] In some embodiments of this application, the output of the amplifier is connected to the source of the field-effect transistor Q1 via a negative feedback low-pass filter circuit. The negative feedback low-pass filter circuit includes a resistor and a capacitor connected in parallel.

[0063] It should be understood that negative feedback amplification of the three-stage amplifier circuit is achieved through a voltage-series negative feedback low-pass filter circuit. This circuit effectively improves the circuit's anti-interference capability and system stability, while also featuring high gain, low noise, extremely low frequency, and wide bandwidth.

[0064] The amplitude-frequency and phase-frequency characteristic curves of the ultra-low noise, high input impedance, ultra-low frequency broadband signal amplifier circuit provided in this application are as follows: Figure 3 , Figure 4 As shown, the circuit exhibits linear amplification and low phase shift in the 0.001-50kHz frequency band.

[0065] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A very low frequency broadband signal amplifier circuit, characterized in that, It includes: First-stage filter circuit: connected to the signal input terminal, used for filtering extremely low frequency signals, the extremely low frequency signals being underwater acoustic signals with a frequency as low as 0.001 Hz; The first-stage amplifier circuit: its input terminal is connected to the output terminal of the first filter circuit; The second-stage amplifier circuit: its input terminal is connected to the output terminal of the first-stage amplifier circuit; The second-stage filter circuit: its input terminal is connected to the output terminal of the second-stage amplifier circuit; The third-stage amplifier circuit: its input terminal is connected to the output terminal of the second-stage filter circuit; Negative feedback low-pass filter circuit: The output of the third-stage amplifier circuit is connected to the input of the first-stage amplifier circuit; The output terminal of the third-stage amplifier circuit serves as the output terminal of the ultra-low frequency broadband signal amplifier circuit.

2. The ultra-low frequency broadband signal amplification circuit according to claim 1, characterized in that, The first-stage amplifier circuit includes a field-effect transistor, whose gate is connected to the output of the first-stage filter circuit; whose source is connected to the negative feedback low-pass filter circuit; and whose drain is connected to the input of the second-stage amplifier circuit.

3. The ultra-low frequency broadband signal amplification circuit according to claim 2, characterized in that, The second-stage amplifier circuit includes a PNP transistor, whose emitter is connected to the system positive power supply through a resistor, whose base is connected to the drain of the field-effect transistor in the first-stage amplifier circuit, and whose collector is connected to the system ground through a resistor and connected to the second-stage filter circuit.

4. The ultra-low frequency broadband signal amplification circuit according to claim 3, characterized in that, The second-stage filter circuit is used for filtering extremely low-frequency signals with frequencies as low as 0.001 Hz. It includes a capacitor and a resistor connected in series. The capacitor is connected to the output of the second-stage amplifier circuit, the resistor is connected to the system ground, and the capacitor and resistor connection is connected to the positive input of the third-stage amplifier circuit.

5. The ultra-low frequency broadband signal amplification circuit according to claim 4, characterized in that, The third-stage amplifier circuit includes an amplifier, the negative input terminal of which is grounded through a resistor and connected to the output terminal through a resistor; the positive input terminal is connected to the output terminal of the second-stage filter circuit; and the output terminal is connected to a signal output interface.

6. The ultra-low frequency broadband signal amplification circuit according to claim 5, characterized in that, The output of the amplifier is connected to the source of the field-effect transistor in the first-stage amplifier circuit via a negative feedback low-pass filter circuit.

7. The ultra-low frequency broadband signal amplification circuit according to claim 6, characterized in that, The negative feedback low-pass filter circuit of the amplifier is a low-pass filter circuit with a resistor and a capacitor connected in parallel.

8. The ultra-low frequency broadband signal amplifier circuit according to claim 1, characterized in that, The first-stage filter circuit and the second-stage filter circuit are RC high-pass filter circuits.

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