An electrical signal sampling device

Abstract

The present application provides an electrical signal sampling device, the device comprising a voltage-dividing resistor and a first active device; the first end of the voltage-dividing resistor is connected to a measured signal source; the second end of the voltage-dividing resistor is connected to the first active device and is grounded through the first active device; the second end of the voltage-dividing resistor serves as a signal sampling point of the measured signal source. By arranging an active device between the voltage-dividing resistor and the ground, the present solution can, on the one hand, utilize the power generated by the active device to increase the power of the signal sampled at the signal sampling point, and on the other hand, can further reduce the equivalent resistance between the measured signal source and the ground through the active device, thereby improving the signal-to-noise ratio of the signal sampled at the signal sampling point.

Description

Technical Field

[0001] The present invention relates to the technical field of signal sampling, and in particular to an electrical signal sampling device. Background Art

[0002] Small signal sampling technology is a signal sampling technology that is widely used in various electronic, electrical and automation equipment. This technology mainly solves the problem of how to accurately sample weak electrical signals in circuits, such as current signals and voltage signals.

[0003] An existing small signal sampling technology solution is to configure a voltage divider resistor between a signal source to be sampled and a ground terminal, and use the voltage divider resistor and the internal resistance of the signal source to sample and obtain the electrical signal generated by the signal source.

[0004] The problem with this solution is that the signal-to-noise ratio of the electrical signal sampled in this way is negatively correlated with the resistance value of the voltage divider resistor, but if the resistance value of the voltage divider resistor is too low, the sampled signal power will be too small. Therefore, when performing small signal sampling based on this solution, it is difficult to obtain a sufficiently high signal-to-noise ratio and signal power at the same time. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides an electrical signal sampling device to provide a small signal sampling solution that can have both high signal-to-noise ratio and high signal power.

[0006] The present application provides an electrical signal sampling device, comprising a voltage-dividing resistor and a first active device;

[0007] The first end of the voltage-dividing resistor is connected to a measured signal source;

[0008] The second end of the voltage-dividing resistor is connected to the first active device and is grounded through the first active device;

[0009] The second end of the voltage-dividing resistor serves as a signal sampling point of the measured signal source.

[0010] Optionally, the first active device includes a first operational amplifier;

[0011] The output end of the first operational amplifier is connected to the second end of the voltage-dividing resistor;

[0012] One input terminal of the first operational amplifier is connected to the first end of the voltage-dividing resistor, and the other input terminal of the first operational amplifier is grounded.

[0013] Optionally, the non-inverting input terminal of the first operational amplifier is grounded, and the inverting input terminal is connected to the first end of the voltage-dividing resistor;

[0014] or,

[0015] A non-inverting input terminal of the first operational amplifier is connected to a first end of the voltage-dividing resistor, and a negative input terminal of the first operational amplifier is grounded.

[0016] Optionally, the device further comprises a second operational amplifier;

[0017] The first end of the voltage-dividing resistor is connected to the input end of the first operational amplifier through the second operational amplifier.

[0018] Optionally, the first end of the voltage-dividing resistor is connected to the second operational amplifier via a first resistor.

[0019] Optionally, the output terminal of the second operational amplifier is connected to the input terminal of the first operational amplifier;

[0020] The first end of the voltage-dividing resistor is connected to the input end of the second operational amplifier.

[0021] Optionally, the first end of the voltage-dividing resistor is connected to the input end of the second operational amplifier, including:

[0022] The non-inverting input terminal of the second operational amplifier is connected to the first end of the voltage dividing resistor;

[0023] Alternatively, the inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor.

[0024] Optionally, when the non-inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier;

[0025] When the inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier.

[0026] Optionally, when the non-inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier via a second resistor;

[0027] When the inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier via the second resistor.

[0028] Optionally, the resistance of the voltage-dividing resistor is related to the internal resistance of the measured signal source.

[0029] The beneficial effects of this application are:

[0030] An active device is arranged between the voltage-dividing resistor and the ground. On the one hand, the power generated by the active device can be used to increase the power of the signal sampled at the signal sampling point. On the other hand, the active device can be used to further reduce the equivalent resistance between the measured signal source and the ground, thereby improving the signal-to-noise ratio of the signal sampled at the signal sampling point. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 A structural schematic diagram of a small signal sampling circuit provided for related technology;

[0033] Figure 2 A schematic diagram of the structure of an electrical signal sampling device provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the structure of another electrical signal sampling device provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of the structure of another electrical signal sampling device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to facilitate understanding of the principle and beneficial effects of the solution provided by this embodiment, a small signal sampling circuit provided by the related art and its working principle are first introduced below. Figure 1 , which is a structural schematic diagram of a small signal sampling circuit provided by the related technology.

[0038] Figure 1In the figure, Us represents the measured signal source, R0 represents the internal resistance of the measured signal source, Uk represents the interference source connected in parallel with the measured signal source, R1 represents the internal resistance of the interference source, and Rs represents the voltage divider resistor, one end of which is connected to the output end of the measured signal source and the other end is grounded. The measured signal source can be a weak current source or a weak voltage source. Generally, R1 is much larger than R0, that is, R1>>R0.

[0039] In this circuit, the common end of the voltage divider resistor and the measured signal source serves as the sampling point of the signal sampling module. The signal sampling module can detect the voltage signal at the sampling point. This voltage signal can be regarded as a sampling signal. It can be understood that the sampling signal can include two parts. One part is the voltage divider signal Uss of the measured signal source acting on the voltage divider resistor, and the other part is the signal voltage divider Uks of the interference source acting on the voltage divider resistor.

[0040] After the signal sampling module obtains the sampled signal, the sampled signal can be processed by other subsequent modules to obtain the real signal Us of the measured signal source.

[0041] right Figure 1 By analyzing the sampling circuit shown in the figure, it can be found that Uss=Us*Rs / (R0+Rs), Uks=Uk*Rs / (R1+Rs). According to the definition of signal-to-noise ratio, the signal-to-noise ratio expression of the existing sampling circuit can be determined as shown in the following formula (1).

[0042] SNR=Uss / Uks=(Us / Uk)*(1+(R1-R0) / (R0+Rs)), (1).

[0043] Since the internal resistance of the measured signal source and the interference source remains basically unchanged during actual signal sampling, it can be considered that the SNR in formula (1) is a dependent variable that changes with Rs. The derivative expression (2) can be obtained by taking the derivative of SNR with respect to Rs.

[0044] dSNR / dRs= Us(R0-R1) / Uk(R0+Rs) 2 , (2).

[0045] Since R1 is greater than R0, dSNR / dRs is always less than 0. As Rs decreases, SNR gradually increases. Therefore, reducing Figure 1 The resistance value of the voltage divider resistor Rs in the sampling circuit can improve the signal-to-noise ratio.

[0046] However, in order to obtain a larger signal power on Rs, Rs cannot be too small.

[0047] The signal power Ps of the measured signal source acting on Rs can be expressed as: Ps=Uss 2 / Rs=Us 2*Rs / (R0+Rs) 2 .

[0048] By observing the expression of the above signal power, it can be found that when Rs=R0, that is, the resistance of the voltage divider resistor is equal to the internal resistance of the measured signal source, the signal power Ps reaches the maximum value, at this time PS=Us 2 / 4Rs, so in order to obtain the maximum signal power on Rs, Rs cannot be too small, which is contradictory to the requirement of taking Rs as small as possible when a high signal-to-noise ratio is required.

[0049] As an example, assuming Rs=R0=1MΩ (megaohm), R1=100MΩ, Us=0.1V, Uk=1V, according to the above expression of signal-to-noise ratio and signal power, it can be calculated that the signal-to-noise ratio is 5.05 and the signal power is 2.5*10 -6 Megawatt (mW).

[0050] In order to solve the contradiction between increasing signal power and increasing signal-to-noise ratio in the above-mentioned existing sampling circuit, the present application provides an electrical signal sampling device, see Figure 2 , Figure 2 The circuit structure in the dotted rectangular frame is the signal sampling device provided in this embodiment. It can be seen that the signal sampling device may include a voltage dividing resistor and a first active device.

[0051] Among them, the voltage divider resistor (i.e. Figure 2 A first end of the resistor R2) shown is connected to a signal source to be measured;

[0052] The second end of the voltage-dividing resistor is connected to the first active device and is grounded through the first active device;

[0053] The second end of the voltage-dividing resistor serves as a signal sampling point of the measured signal source.

[0054] Rs is the equivalent resistance between the output terminal of the signal sampling device of this embodiment and the ground of the signal source under test.

[0055] The first active device may be an amplifier or other active devices, which is not limited in this embodiment.

[0056] Ui represents the voltage signal at the output end where the measured signal source and the interference source are connected in parallel, and Is represents the signal current output by the measured signal source at the output end.

[0057] When the device is working, the first active device can be powered by an external power supply, and a sampling signal can be obtained through a signal sampling module. The sampling signal can be a voltage signal or a current signal at a sampling point. The sampling signal is then processed by other modules subsequent to the signal sampling module to obtain a real signal of the signal source under test.

[0058] The measured signal source of this embodiment may be a small signal source that generates a tiny current. Exemplarily, the current generated by the measured signal source may be between 100 pA (picoampere) and 1 μA (microampere).

[0059] The beneficial effects of this embodiment are:

[0060] An active device is arranged between the voltage-dividing resistor and the ground. On the one hand, the power generated by the active device can be used to increase the power of the signal sampled at the signal sampling point. On the other hand, the active device can be used to further reduce the equivalent resistance between the measured signal source and the ground, thereby improving the signal-to-noise ratio of the signal sampled at the signal sampling point.

[0061] In some optional embodiments, see Figure 3 , the first active device of this embodiment may be a first operational amplifier.

[0062] An output terminal of the first operational amplifier is connected to a second terminal of the voltage dividing resistor;

[0063] One input terminal of the first operational amplifier is connected to the first end of the voltage-dividing resistor, and the other input terminal of the first operational amplifier is grounded.

[0064] The connection relationship between the first operational amplifier and the voltage dividing resistor may be:

[0065] The non-inverting input terminal of the first operational amplifier is grounded, and the inverting input terminal of the first operational amplifier is connected to the first end of the voltage dividing resistor;

[0066] Alternatively, the non-inverting input terminal of the first operational amplifier is connected to the first end of the voltage-dividing resistor, and the inverting input terminal of the first operational amplifier is grounded.

[0067] Further optionally, a resistor R4 may be connected in series between the input terminal of the first operational amplifier and the first terminal of the voltage-dividing resistor.

[0068] The advantage of connecting the first end of the voltage-dividing resistor to the input end of the first operational amplifier is that the voltage of the first end of the voltage-dividing resistor is limited to 0V by utilizing the virtual short end characteristic of the first operational amplifier, thereby facilitating obtaining the real signal of the measured signal source from the sampled signal.

[0069] In some optional embodiments, in order to improve the stability of the sampling device of this embodiment, see Figure 4 , the sampling device also includes a second operational amplifier;

[0070] The second operational amplifier may be located between the first end of the voltage-dividing resistor and the input end of the first operational amplifier, that is, the first end of the voltage-dividing resistor may be connected to the input end of the first operational amplifier through the second operational amplifier.

[0071] The first end of the voltage divider resistor can be directly connected to the second operational amplifier, or can be connected through the first resistor, that is, Figure 4 Resistor R4 is shown connected to the second operational amplifier.

[0072] When the second operational amplifier is connected through the first resistor, one end of the first resistor is connected to the first end of the voltage-dividing resistor, and the other end of the first resistor is connected to the second operational amplifier.

[0073] When a second operational amplifier is also included, the input end of the second operational amplifier can be directly connected to the first end of the voltage divider resistor, or can be connected to the other end of the first resistor and connected to the first end of the voltage divider resistor through the first resistor.

[0074] The output of the second operational amplifier can be connected to the input of the first operational amplifier. Specifically, the output of the second operational amplifier can be connected to the non-inverting input of the first operational amplifier, and the inverting input of the first operational amplifier is grounded. Alternatively, the output of the second operational amplifier can be connected to the inverting input of the first operational amplifier, and the non-inverting input of the first operational amplifier is grounded.

[0075] Optionally, when the first end of the voltage divider resistor is connected to the input end of the second operational amplifier, the first end of the voltage divider resistor can be specifically connected to the non-phase input end of the second operational amplifier (which can be directly connected or connected through the first resistor), or the first end of the voltage divider resistor can be specifically connected to the inverting input end of the second operational amplifier (which can be directly connected or connected through the first resistor).

[0076] Further, still healthy Figure 4 , when the non-inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the inverting input terminal of the second operational amplifier may be connected to the output terminal of the second operational amplifier;

[0077] In contrast, when the inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier.

[0078] When the non-inverting input terminal of the second operational amplifier is connected to the first end of the voltage divider resistor, the connection mode of the inverting input terminal and the output terminal thereof may be that the inverting input terminal of the second operational amplifier is directly connected to the output terminal of the second operational amplifier, or the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier via the second resistor (i.e. Figure 4 The resistor R3) is connected to the output terminal of the second operational amplifier.

[0079] When the inverting input terminal of the second operational amplifier is connected to the first end of the voltage divider resistor, the connection method of its non-inverting input terminal and output terminal can be that the non-inverting input terminal of the second operational amplifier is directly connected to the output terminal of the second operational amplifier, or the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through the second resistor.

[0080] In some optional embodiments, in order to obtain the largest possible signal power at the sampling point, the resistance value of the voltage divider resistor can be determined according to the resistance value of the internal resistance of the measured signal source, that is, the resistance value of the voltage divider resistor is related to the internal resistance of the measured signal source. As an example, the resistance value of the voltage divider resistor can be set to be equal to the internal resistance of the measured signal source.

[0081] Figure 4 The operating principle of the device shown is as follows.

[0082] Assume that the open-loop gains of the first operational amplifier and the second operational amplifier are both AoI (approximately 10 4 ~10 7 ), since the non-inverting input terminal of the first operational amplifier (i.e. Figure 4 The 3rd terminal shown in the figure is grounded, so the voltage U3 here is equal to 0. According to the virtual short and virtual open characteristics of the operational amplifier, (U3-U2) = Uss / AoI≈0, and then it can be considered that U2=-Uss / AoI≈0.

[0083] Further using the virtual short and virtual break characteristics of the operational amplifier, it can be known that the current flowing through the first resistor R4 is 0, that is, Figure 4 The voltage U5 at terminal 5, the voltage U6 at terminal 6, and the voltage Ui at the first end of the voltage-dividing resistor are all equal to U2, that is, approximately equal to 0, that is, Ui=U5=U6=U2=-Uss / AoI≈0.

[0084] For the signal current Is, since the current flowing through the first resistor is 0, it can be considered that the current flowing through the voltage divider resistor is equal to the signal current Is. Considering that Ui=-Uss / AoI, it can be determined that Is = (Ui-Uss) / R2=Ui*(1+AoI) / R2, Rs=Ui / Is=R2 / (1+AoI)≈R2 / AoI.

[0085] In combination with the above example, assuming that R2=R0=1MΩ (megaohm), R1=100MΩ, Us=0.1V, Uk=1V, it can be calculated based on the above expressions of signal-to-noise ratio and signal power. At this time, the signal-to-noise ratio SNR is SNR=Uss / Uks=(Us / Uk)*(1+(R1-R0) / (R0+Rs)), where Rs=R2 / AoI, so R0+Rs is approximately equal to R0, and then SNR≈10 can be calculated.

[0086] In addition, since the current flowing through the first resistor is 0, the signal current output by the measured signal source can be considered to be equal to the current flowing through the voltage divider resistor, that is, (Us-Ui) / R0=(Ui-Uss) / R2. Since Ui is approximately equal to 0, it can be considered that Uss≈Us*R2 / R0. In the above example, the resistance values ​​of R2 and R0 are equal, both 1MΩ, so it can be determined that Uss≈Us. Therefore, the signal power Ps at the signal sampling point can be calculated according to the following formula:

[0087] Ps=Uss 2 / R2=Us 2 / R2=1*10 -5 mW.

[0088] By comparing the signal-to-noise ratio of the present embodiment with the signal-to-noise ratio in the aforementioned example of the prior art, and the signal power of the present embodiment with the power in the aforementioned example of the prior art, it can be found that under the same conditions, that is, R2=R0=1MΩ (megaohm), R1=100MΩ, Us=0.1V, Uk=1V, the present embodiment improves the signal-to-noise ratio at the signal sampling point by 2 times relative to the prior art, and improves the signal power at the signal sampling point by 4 times relative to the prior art. It can be seen that, compared with the existing small signal sampling circuit, the present embodiment can simultaneously improve the signal-to-noise ratio and signal power during small signal sampling.

[0089] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0090] It should be noted that the concepts such as “first” and “second” mentioned in the present invention are only used to distinguish different systems, modules or units, and are not used to limit the order or interdependence of the functions performed by these systems, modules or units.

[0091] The present application can be implemented or used by professionals and technicians. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrical signal sampling device, characterized in that: including a voltage-dividing resistor and a first active device; The first end of the voltage-dividing resistor is connected to a measured signal source; The second end of the voltage-dividing resistor is connected to the first active device and is grounded through the first active device; The second end of the voltage-dividing resistor serves as a signal sampling point of the measured signal source; The first active device comprises a first operational amplifier; The apparatus also includes a second operational amplifier; The output end of the first operational amplifier is connected to the second end of the voltage-dividing resistor; One input terminal of the first operational amplifier is connected to the output terminal of the second operational amplifier so as to be connected to the first end of the voltage-dividing resistor through the second operational amplifier, and the other input terminal of the first operational amplifier is grounded; Any one of the non-inverting input terminal and the inverting input terminal of the second operational amplifier is connected to the first terminal of the voltage dividing resistor; The other of the non-inverting input terminal and the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier.

2. The device according to claim 1, characterized in that The non-inverting input terminal of the first operational amplifier is grounded, and the inverting input terminal is connected to the first end of the voltage-dividing resistor; or, A non-inverting input terminal of the first operational amplifier is connected to a first end of the voltage-dividing resistor, and a negative input terminal of the first operational amplifier is grounded.

3. The device according to claim 1, characterized in that The first end of the voltage-dividing resistor is connected to the second operational amplifier through a first resistor.

4. The device according to claim 1, characterized in that When the non-inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through the second resistor; When the inverting input terminal of the second operational amplifier is connected to the first end of the voltage-dividing resistor, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier via the second resistor.

5. The device according to claim 1, characterized in that The resistance value of the voltage-dividing resistor is related to the internal resistance of the measured signal source.

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