Current sampling circuit and current sampling system

Abstract

The invention discloses a current sampling circuit and a current sampling system, and relates to the technical field of signal sampling, and the circuit comprises a sampling module which is connected with a to-be-tested device and a gating module, and a control module which is connected with the to-be-tested device and the gating module; the control module is used for acquiring current information of the to-be-tested equipment and transmitting a gating signal to the gating module according to the current information; and the gating module is used for selecting a target sampling unit from the sampling module to sample the to-be-detected current transmitted by the to-be-detected equipment according to the gating signal. And the sampling module is used for generating a corresponding potential difference signal according to the current to be measured and transmitting the potential difference signal to the control module through the gating module. Compared with the prior art, the continuous current path is formed by the at least two sampling units connected in series, and the target sampling unit is selected based on the gating signal to perform differential sampling, so that the current is kept uninterrupted during range switching, and the system stability and the measurement precision are improved.

Description

Technical Field

[0001] This application relates to the field of signal sampling technology, and in particular to a current sampling circuit and a current sampling system. Background Technology

[0002] In the field of precision current measurement, especially in semiconductor testing, source measurement units (SMUs), and multi-range instruments, accurate sampling of multiple current ranges from microamperes to amperes is often required. The traditional sampling method uses parallel switching of multiple resistors, where a switch selects the sampling resistor branch corresponding to the range, while the others are disconnected. This method causes a momentary interruption in the current loop when switching sampling ranges, leading to abrupt changes in the operating state of the circuit under test and potentially introducing switching noise and voltage spikes, affecting system stability and measurement continuity. Furthermore, in the parallel structure, each sampling resistor is independently grounded, making it susceptible to common-mode interference and ground loop noise, reducing sampling accuracy.

[0003] Therefore, how to maintain the continuity of the current path and achieve high-precision differential measurement during multi-level current sampling is an urgent problem to be solved. Summary of the Invention

[0004] The main purpose of this application is to provide a current sampling circuit and a current sampling system, which aims to solve the technical problem of how to maintain the continuity of the current path and achieve high-precision differential measurement during multi-level current sampling.

[0005] To achieve the above objectives, this application proposes a current sampling circuit, which includes a sampling module, a gating module, and a control module, wherein the sampling module has at least two sampling units connected in series. The sampling module is connected to the device under test and the gating module, respectively, and the control module is connected to the device under test and the gating module, respectively. The control module is used to acquire the current information of the device under test and transmit a gating signal to the gating module according to the current information; The gating module is used to select a target sampling unit from the sampling module to sample the current to be measured transmitted by the device under test according to the gating signal; the sampling module is used to generate a corresponding potential difference signal according to the current to be measured, and transmit the potential difference signal to the control module through the gating module.

[0006] In one embodiment, the sampling unit includes: Sampling resistor, balancing capacitor, and bypass switch; The first end of the sampling resistor is connected to the first end of the balancing capacitor, the first end of the bypass switch, the device under test, and the gating module, respectively. The second end of the sampling resistor is connected to the second end of the balancing capacitor, the second end of the bypass switch, and the gating module, respectively.

[0007] In one embodiment, the gating module includes: a potential acquisition unit and a channel selection unit; The input terminal of the potential acquisition unit is connected to the nodes of each sampling unit in the sampling module to acquire the potential difference signal of each node. The channel selection unit is connected to the output terminal of the potential acquisition unit and the control module, respectively. The channel selection unit is used to select the potential difference signal corresponding to the target sampling unit from the potential difference signals of each node according to the gating signal, and output the potential difference signal to the control module.

[0008] In one embodiment, the control module includes: an information acquisition unit, a signal generation unit, and a signal receiving unit; The information acquisition unit is connected to the device under test and is used to acquire the current information of the device under test; The signal generation unit is connected to the information acquisition unit and is used to generate the gating signal according to the current information and transmit the gating signal to the gating module. The signal receiving unit is connected to the gating module and is used to receive the potential difference signal transmitted by the gating module.

[0009] In one embodiment, the potential acquisition unit includes at least three voltage followers; The input terminal of the voltage follower is connected to the node of each sampling unit in the sampling module, and the output terminal of the voltage follower is connected to the channel selection unit.

[0010] In one embodiment, the circuit further includes a signal: a signal conditioning module; The signal conditioning module is connected between the gating module and the control module and is used to amplify the potential difference signal.

[0011] In one embodiment, the circuit further includes: a direction switching module; The direction switching is connected between the gating module and the signal conditioning module, and is used to switch the polarity of the potential difference signal input to the signal conditioning module according to the direction of the current to be measured.

[0012] In one embodiment, the signal conditioning module includes: an instrumentation amplifier; The differential input terminal of the instrumentation amplifier is connected to the gating module to receive the potential difference signal; The output terminal of the instrumentation amplifier is connected to the control module, and is used to transmit the amplified potential difference signal to the control module.

[0013] In one embodiment, the direction switching module includes: a single-pole double-throw switch unit; The single-pole double-throw switch unit is connected between the gating module and the signal conditioning module, and is used to change the differential polarity of the potential difference signal input to the signal conditioning module by switching the physical connection path.

[0014] In addition, to achieve the above objectives, this application also proposes a current sampling system, which includes the current sampling circuit as described above.

[0015] This application proposes a current sampling circuit and a current sampling system. The circuit includes a sampling module, a gating module, and a control module. The sampling module has at least two sampling units connected in series. The sampling module is connected to both the device under test (DUT) and the gating module. The control module is connected to both the DUT and the gating module. The control module acquires the current information of the DUT and transmits a gating signal to the gating module based on the current information. The gating module selects a target sampling unit from the sampling module to sample the current transmitted by the DUT based on the gating signal. The sampling module generates a corresponding potential difference signal based on the current and transmits the potential difference signal to the control module through the gating module.

[0016] This application incorporates a current sampling circuit within a current sampling system. A sampling module is connected to both the device under test (DUT) and a gating module, while a control module is also connected to both. The control module acquires the current information from the DUT and transmits a gating signal to the gating module based on this information. The gating module selects a target sampling unit from the sampling modules based on the gating signal to sample the current transmitted by the DUT. The sampling module generates a corresponding potential difference signal based on the current under test and transmits this signal to the control module via the gating module. Compared to existing systems, this application improves system stability and measurement accuracy by constructing a continuous current path using at least two series-connected sampling units and selecting a target sampling unit for differential sampling based on the gating signal. This ensures uninterrupted current flow during range switching. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application 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.

[0019] Figure 1 This is a schematic diagram of the structure of the first embodiment of the current sampling circuit proposed in this application; Figure 2 This is a schematic diagram of the structure of the second embodiment of the current sampling circuit proposed in this application; Figure 3 This is a schematic diagram of the third embodiment of the current sampling circuit proposed in this application.

[0020] Explanation of reference numerals in the attached figures:

[0021] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0025] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0026] It should be noted that in the field of precision current measurement, especially in semiconductor testing, source measurement units (SMUs), and multi-range instruments, accurate sampling of multiple current ranges from microamperes to amperes is often required. The traditional sampling method uses parallel switching of multiple resistors, where a switch selects the sampling resistor branch corresponding to the range, while the others are disconnected. This method causes a momentary interruption in the current loop when switching sampling ranges, leading to abrupt changes in the operating state of the circuit under test and potentially introducing switching noise and voltage spikes, affecting system stability and measurement continuity. Furthermore, in the parallel structure, each sampling resistor is independently grounded, making it susceptible to common-mode interference and ground loop noise, reducing sampling accuracy.

[0027] To address the aforementioned technical problems, this embodiment proposes a current sampling circuit. This embodiment includes a current sampling circuit within the current sampling system. Sampling module 1 is connected to the device under test (DUT) 4 and gating module 2, respectively. Control module 3 is also connected to DUT 4 and gating module 2. Control module 3 acquires the current information of DUT 4 and transmits a gating signal to gating module 2 based on the current information. Gating module 2 selects a target sampling unit from sampling module 1 based on the gating signal to sample the current transmitted by DUT 4. Sampling module 1 generates a corresponding potential difference signal based on the current under test and transmits the potential difference signal to control module 3 through gating module 2. Compared to existing methods, this embodiment, by constructing a continuous current path using at least two series-connected sampling units and selecting a target sampling unit for differential sampling based on the gating signal, maintains uninterrupted current flow during range switching, thereby improving system stability and measurement accuracy.

[0028] For ease of understanding, the following is combined with Figures 1 to 3 The current sampling circuit provided in the embodiments of this application will be described in detail.

[0029] Reference Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the current sampling circuit proposed in this application.

[0030] like Figure 1As shown, in this embodiment, the circuit includes: a sampling module 1, a gating module 2, and a control module 3. The sampling module 1 is provided with at least two sampling units connected in series. The sampling module 1 is connected to the device under test 4 and the gating module 2 respectively, and the control module 3 is connected to the device under test 4 and the gating module 2 respectively. The control module 3 is used to acquire the current information of the device under test 4 and transmit a gating signal to the gating module 2 according to the current information; The gating module 2 is used to select a target sampling unit from the sampling module 1 to sample the current to be measured transmitted by the device under test 4 according to the gating signal; The sampling module 1 is used to generate a corresponding potential difference signal based on the current to be measured, and transmit the potential difference signal to the control module 3 through the gating module 2.

[0031] It should be noted that sampling module 1 can be a circuit section used to carry the measured current and convert it into a voltage signal. Sampling module 1 contains at least two sampling units connected in series to form a continuous current path. The sampling unit can be any module capable of current-to-voltage conversion and having a bypass function, for example, a unit consisting of a precision sampling resistor R, a balancing capacitor C for dynamic compensation, and a switch (such as an optocoupler TLP3556A) connected in parallel for selective access or bypass. The overall connection method of sampling module 1 is as follows: after all sampling units are connected in series, their first and last ends are respectively connected to the current loop of the device under test 4, thereby realizing the continuous flow of current.

[0032] The gating module 2 can be a circuit section used to select a specific signal pair from multiple nodes of the sampling module 1. The gating module 2 receives a gating signal from the control module 3 and, based on this signal, determines which of the sampling units in the sampling module 1 is the current target sampling unit, thereby selecting the potential signal across the target sampling unit. The gating module 2 can be any circuit combination capable of implementing multi-channel differential signal selection; for example, it can be a potential acquisition front-end composed of a set of voltage followers 211, combined with a channel selection circuit composed of multiple analog switches (such as ADG1204).

[0033] Control module 3 can be a circuit section used to manage the sampling process and process signals. Control module 3 is responsible for acquiring current information (such as a preset range or a rough estimate) from the device under test 4 or the test system, generating a command (i.e., a gating signal) for selecting the target sampling unit based on this information, and sending it to gating module 2. Simultaneously, control module 3 also receives a potential difference signal representing the magnitude of the measured current transmitted from gating module 2 for subsequent calculation, display, or control. Control module 3 can be any unit with logic processing and signal interface functions, for example, composed of a microcontroller (MCU), a field-programmable gate array (FPGA), or dedicated logic circuits. Its information acquisition unit 31 can be implemented through a digital communication interface or an analog monitoring channel.

[0034] Understandably, current information can be reference data or instructions used to determine the current sampling range. Current information can be any data format that can indicate the approximate range or specific range of the current to be measured, such as the range value set by the user through the host computer software (e.g., "1mA range"), the current range initially estimated by the automatic ranging function, or preset parameters from the test sequence.

[0035] The strobe signal can be a control command issued by the control module 3 to instruct the strobe module 2 to select a specific sampling unit. The strobe signal can be any level or digital signal capable of encoding the identity of the target sampling unit, such as a specific combination of TTL logic levels or a serial communication message containing address information.

[0036] The potential difference signal can be a voltage difference analog signal that directly characterizes the magnitude of the measured current. The potential difference signal is generated across the target sampling resistor R in sampling module 1, and its voltage value (U), the current flowing through it (I), and the resistance value (R) satisfy Ohm's law (U=I×R). The potential difference signal is any differential voltage proportional to the current; for example, a 1V voltage difference generated when a 1mA current flows through a 1kΩ resistor.

[0037] In its implementation, control module 3 first acquires the current information of the device under test (DUT) 4. This current information may originate from user settings, preliminary judgment of the automatic range, or the results of the previous test cycle. Based on this information, control module 3 generates a specific gating signal and sends it to gating module 2. Upon receiving this signal, gating module 2 precisely connects the electrical connections at both ends of the target sampling unit from all sampling units of sampling module 1. At this time, the current under test flows through the entire series-connected sampling module 1, generating a voltage drop across the target sampling unit. This voltage drop, as a potential difference signal, is captured by gating module 2 and transmitted back to control module 3, thus completing one current sampling. The entire process ensures that the main path of the measured current remains continuous regardless of which sampling unit is selected for measurement, overcoming the problem of current interruption caused by traditional parallel switching methods.

[0038] The current sampling system in this embodiment includes a current sampling circuit. Sampling module 1 is connected to the device under test (DUT) 4 and gating module 2, respectively. Control module 3 is also connected to DUT 4 and gating module 2. Control module 3 acquires the current information of DUT 4 and transmits a gating signal to gating module 2 based on the current information. Gating module 2 selects a target sampling unit from sampling module 1 based on the gating signal to sample the current transmitted by DUT 4. Sampling module 1 generates a corresponding potential difference signal based on the current under test and transmits the potential difference signal to control module 3 through gating module 2. Compared to existing systems, this embodiment improves system stability and measurement accuracy by constructing a continuous current path using at least two series-connected sampling units and selecting a target sampling unit for differential sampling based on the gating signal. This ensures uninterrupted current flow during range switching.

[0039] Reference Figure 2 , Figure 2 This is a schematic diagram of the structure of the second embodiment of the current sampling circuit proposed in this application.

[0040] Based on the above embodiments, a second embodiment of this application is proposed. In order to collect the current of the device under test 4, such as... Figure 2 As shown, in this embodiment, the sampling unit includes: Sampling resistor R, balancing capacitor C, and bypass switch K; The first end of the sampling resistor R is connected to the first end of the balancing capacitor C, the first end of the bypass switch K, the device under test 4, and the gating module 2, respectively. The second end of the sampling resistor R is connected to the second end of the balancing capacitor C, the second end of the bypass switch K, and the gating module 2, respectively.

[0041] It should be noted that the sampling resistor R can be any resistor element with precision current-to-voltage conversion function, such as a chip resistor with an accuracy of 0.1% and a temperature characteristic of 50ppm / ℃, whose resistance value can range from 1MΩ to 1Ω depending on the range requirements.

[0042] The balancing capacitor C can be any capacitive element used to compensate for dynamic characteristics, such as a ceramic capacitor connected in parallel across the sampling resistor R to balance the dynamic effects of the device under test. The balancing capacitor C is used to improve the frequency response of the sampling node and suppress voltage fluctuations caused by rapidly changing currents.

[0043] The bypass switch K can be any switching element that achieves electrical isolation on / off control, such as the optocoupler switch TLP3556A, used to provide a low-impedance bypass path for current in the non-sampling state. The state of the bypass switch K determines whether the current flows through the sampling resistor R or bypasses it.

[0044] In the specific implementation, the first end of the sampling resistor R is simultaneously connected to the first end of the balancing capacitor C and the first end of the bypass switch K, and is led out to the current loop of the device under test 4 and the potential acquisition point of the gating module 2. The second end of the sampling resistor R is simultaneously connected to the second end of the balancing capacitor C and the second end of the bypass switch K, and is led out to another potential acquisition point of the gating module 2. When the sampling unit is selected as the target sampling unit, the bypass switch K remains open, and the current to be measured flows entirely through the sampling resistor R, generating a potential difference across it for sampling. When the sampling unit is not selected, the bypass switch K closes, providing a parallel path with extremely low resistance for the current, allowing most of the current to flow through the bypass switch K, thereby effectively bypassing the sampling resistor R from the main current path and avoiding the introduction of unnecessary voltage drops and power consumption.

[0045] Furthermore, in order to select the target signal from multiple sampling points, the process continues as follows: Figure 2 As shown, in this embodiment, the gating module 2 includes: a potential acquisition unit 21 and a channel selection unit 22; The input terminal of the potential acquisition unit 21 is connected to the nodes of each sampling unit in the sampling module 1, and is used to acquire the potential difference signal of each node. The channel selection unit 22 is connected to the output terminal of the potential acquisition unit 21 and the control module 3, respectively. The channel selection unit 22 is used to select the potential difference signal corresponding to the target sampling unit from the potential difference signals of each node according to the gating signal, and output the potential difference signal to the control module 3.

[0046] It should be noted that the potential acquisition unit 21 can be any circuit set with high input impedance used to acquire and buffer voltage signals, such as an array of voltage followers 211 composed of multiple operational amplifiers (such as SGM8255A). Each input terminal of the potential acquisition unit 21 is connected to a node of a sampling unit in the sampling module 1 to acquire the potential of that node to ground in real time.

[0047] The channel selection unit 22 can be any digitally controlled circuit used to select one or a pair of signals from multiple inputs, such as a multiplexer or analog switch integrated circuit (e.g., ADG1204). The input terminals of the channel selection unit 22 are connected to all the output terminals of the potential acquisition unit 21, the control terminal is used to receive the selection signal from the control module 3, and the output terminal is used to output the selected signal.

[0048] In the specific implementation, the potential acquisition unit 21 operates continuously, with each voltage follower 211 independently acquiring and buffering the potential of the corresponding node in the sampling module 1. All buffered node potential signals are sent in parallel to multiple input terminals of the channel selection unit 22. When the control module 3 needs to measure the current, it sends a gating signal representing a specific target sampling unit to the channel selection unit 22. Upon receiving the gating signal, the channel selection unit 22 activates its internal switching array, precisely selecting from all input signals the two buffered potential signals corresponding to the two nodes at the ends of the target sampling unit, and outputting these two signals as a pair of differential potential difference signals. This process enables the measurement of the voltage difference across any specific resistor in a series resistor chain without physically switching the current path, solely through selective switching of electrical connections.

[0049] Furthermore, in order to manage and coordinate the entire current sampling process, continue as follows... Figure 2 As shown, in this embodiment, the control module 3 includes: an information acquisition unit 31, a signal generation unit 32, and a signal receiving unit 33; The information acquisition unit 31 is connected to the device under test 4 and is used to acquire the current information of the device under test 4; The signal generation unit 32 is connected to the information acquisition unit 31 and is used to generate the gating signal according to the current information and transmit the gating signal to the gating module 2. The signal receiving unit 33 is connected to the gating module 2 and is used to receive the potential difference signal transmitted by the gating module 2.

[0050] It should be noted that the information acquisition unit 31 can be any interface or logic circuit used to receive or determine the range parameters of the current to be measured, such as a communication interface (such as SPI or UART) that receives test instructions from a host computer, or a microcontroller that outputs range codes according to a preset test sequence.

[0051] The signal generation unit 32 can be any logic circuit that generates specific control commands based on range parameters. For example, it can be a digital logic circuit or microprocessor that translates the range code (such as "1mA range") into the corresponding multiplexer address code. The signal generation unit 32 translates the current information output by the information acquisition unit 31 into a gating signal that the gating module 2 can directly recognize and execute.

[0052] The signal receiving unit 33 can be any input interface circuit used to receive analog voltage signals, such as the analog front end or differential receiving pin of an analog-to-digital converter (ADC). The signal receiving unit 33 is responsible for receiving the analog voltage signal representing the potential difference across the target sampling resistor R transmitted by the gating module 2.

[0053] In its implementation, when the test system decides to measure a 1mA current, this 1mA range instruction is sent as current information to the information acquisition unit 31. After obtaining the current information from the information acquisition unit 31, the signal generation unit 32 immediately converts it into a specific, executable command, such as a set of binary gating signals that connect the internal switch of the gating module 2 to the corresponding node of the 1KΩ resistor, and sends the gating signals to the gating module 2. Subsequently, the gating module 2 completes the measurement of the target sampling unit according to the gating signals and sends the obtained potential difference signal (e.g., 0.5V) back to the control module 3. The signal receiving unit 33 is responsible for receiving the potential difference signal and providing it to other circuits inside or outside the control module 3 for final processing and calculation, thereby obtaining an accurate current value.

[0054] Furthermore, in order to achieve the acquisition and buffering of the potential signal, we continue as follows... Figure 2 As shown, in this embodiment, the potential acquisition unit 21 includes at least three voltage followers 211; The input terminal of the voltage follower 211 is connected to the node of each sampling unit in the sampling module 1, and the output terminal of the voltage follower 211 is connected to the channel selection unit 22.

[0055] It should be noted that the voltage follower 211 can be any operational amplifier circuit with high input impedance and unity-gain buffer characteristics, such as a non-inverting amplifier circuit (gain of 1) connected using an SGM8255A operational amplifier.

[0056] In a specific implementation, the potential acquisition unit 21 consists of at least three voltage followers 211. The input of each voltage follower 211 is independently and one-to-one connected to a node of a specific sampling unit in the sampling module 1, used to directly acquire the node's potential relative to ground. The output of each voltage follower 211 is connected to the corresponding input of the channel selection unit 22. For example, for a sampling module 1 with seven sampling resistors R connected in series, the potential acquisition unit 21 will use eight voltage followers 211, connected to eight nodes across all resistors. When current flows through the sampling module 1, the potential of each node is acquired and buffered in real time by the connected voltage follower 211. The buffered multiple potential signals output by the voltage followers 211 collectively constitute the source for signal selection by the channel selection unit 22.

[0057] Reference Figure 3 , Figure 3 This is a schematic diagram of the third embodiment of the current sampling circuit proposed in this application.

[0058] Based on the above embodiments, a third embodiment of this application is proposed. In order to perform gain processing on the original potential difference signal representing the current magnitude, such as... Figure 3 As shown, in this embodiment, the circuit further includes a signal conditioning module 5; The signal conditioning module is connected between the gating module 2 and the control module 3, and is used to amplify the potential difference signal.

[0059] It should be noted that the signal conditioning module 5 can be any module used to amplify, filter or transform analog small signals, such as the instrumentation amplifier 51 (e.g., SGM621).

[0060] In its implementation, the signal conditioning module 5 is connected between the output of the gating module 2 and the signal receiving unit 33 of the control module 3. The raw potential difference signal, representing the voltage across the target sampling resistor R, output by the gating module 2, is first sent to the signal conditioning module 5. For example, when a weak potential difference signal (e.g., 0.1V) is output from the gating module 2, the signal conditioning module 5 (e.g., an instrumentation amplifier 51 with a gain of 5x) amplifies the potential difference signal into a voltage signal (e.g., 0.5V) with a more suitable amplitude for processing, according to a preset multiplier. The amplified voltage signal is then transmitted from the output of the signal conditioning module 5 to the signal receiving unit 33 of the control module 3 for subsequent analog-to-digital conversion and calculation. The addition of the signal conditioning module 5 significantly improves the system's ability to distinguish and measure minute current signals.

[0061] Furthermore, to ensure the consistency of the measured signal polarity under different current directions, the following steps are continued... Figure 3 As shown, in this embodiment, the circuit further includes: a direction switching module 6; The direction switching is connected between the gating module 2 and the signal conditioning module 5, and is used to switch the polarity of the potential difference signal input to the signal conditioning module 5 according to the direction of the current to be measured.

[0062] It should be noted that the direction switching module 6 can be any circuit that can controllably change the connection path of the two signals, such as a switching circuit composed of a single-pole double-throw analog switch (e.g., ADG1236). The direction switching module 6 is specifically used to switch the connection order of the two differential signals input to the signal conditioning module 5 according to the actual flow direction of the measured current.

[0063] In its implementation, the direction switching module 6 is connected between the output of the gating module 2 and the input of the signal conditioning module 5. The potential difference signal (e.g., the potentials of nodes N2 and N3) output from the gating module 2, originating from the target sampling resistor R, is first fed into the two inputs of the direction switching module 6. The direction switching module 6 operates based on an independently acquired direction signal reflecting the direction of the current under test (e.g., a high / low level provided by the source meter control circuit). When the current direction is from left to right, the direction switching module 6 connects the first signal (e.g., the N2 potential) output from the gating module 2 to the positive input (IN+) of the signal conditioning module 5 and the second signal (e.g., the N3 potential) to the negative input (IN-) of the signal conditioning module 5. When the current direction is from right to left, the direction switching module 6 performs the opposite operation, connecting the first signal (N2 potential) to IN- and the second signal (N3 potential) to IN+.

[0064] Furthermore, in order to amplify the weak differential voltage signal into a single-ended voltage signal referenced to ground, the following steps are continued... Figure 3 As shown, in this embodiment, the signal conditioning module 5 includes: an instrumentation amplifier 51; The differential input terminal of the instrumentation amplifier 51 is connected to the gating module 2 and is used to receive the potential difference signal; The output terminal of the instrumentation amplifier 51 is connected to the control module 3, and is used to transmit the amplified potential difference signal to the control module 3.

[0065] It should be noted that the instrumentation amplifier 51 can be any integrated circuit or discrete circuit with high input impedance, high common-mode rejection ratio and precision differential amplification capability, such as the SGM621 instrumentation amplifier 51 chip.

[0066] In its implementation, the differential input terminals (positive input IN+ and negative input IN-) of the instrumentation amplifier 51 are connected to the output of the gating module 2 (or via the direction switching module 6) to receive the raw potential difference signal from the target sampling resistor R. The output of the instrumentation amplifier 51 is directly connected to the input of the signal receiving unit 33 in the control module 3. For example, when the gating module 2 outputs a 0.1V differential signal, the instrumentation amplifier 51 amplifies the signal to a single-ended output voltage of 0.5V through a precision resistor network (e.g., configured as a 5x gain) placed between the gain pins of the instrumentation amplifier 51.

[0067] Furthermore, in order to achieve the physical exchange of differential signal polarity through basic switching elements, continuing as follows... Figure 3 As shown, in this embodiment, the direction switching module 6 includes: a single-pole double-throw switch unit 61; The single-pole double-throw switch unit 61 is connected between the gating module 2 and the signal conditioning module 5, and is used to change the differential polarity of the potential difference signal input to the signal conditioning module 5 by switching the physical connection path.

[0068] It should be noted that the single-pole double-throw switch unit 61 can be any electronic switch with one moving end and two stationary ends, and capable of switching the moving end to different stationary ends according to the control level, such as an independent switch channel in an analog switch integrated circuit (such as ADG1236).

[0069] In its implementation, the direction switching module 6 typically consists of two single-pole double-throw (SPDT) switch units 61. The moving terminal of the first SPDT switch unit 61 is connected to the first signal line output by the gating module 2 (e.g., the potential corresponding to the left node of the target sampling resistor R), while its two stationary terminals are connected to the positive input (IN+) and negative input (IN-) of the instrumentation amplifier 51 of the signal conditioning module 5, respectively. The moving terminal of the second SPDT switch unit 61 is connected to the second signal line output by the gating module 2 (e.g., the potential corresponding to the right node of the target sampling resistor R), and the connection order of its two stationary terminals is reversed compared to the first switch, i.e., connected to the negative input (IN-) and positive input (IN+) of the instrumentation amplifier 51, respectively. When polarity needs to be switched, a unified direction control signal synchronously changes the connection position of the moving terminals of the two SPDT switch units 61. For example, when the control signal is high, both moving terminals are connected to the first stationary terminal, so that the original first and second signals enter IN+ and IN- respectively; when the control signal is low, the two moving terminals synchronously switch to the second stationary terminal, so that the original first and second signals are swapped and sent to IN- and IN+ respectively.

[0070] To achieve the above objectives, this application also proposes a current sampling system, which includes the current sampling circuit described above.

[0071] It should be noted that the specific implementation of the current sampling system provided in this embodiment can refer to the above embodiments, and this embodiment will not elaborate on it further. Therefore, the effects achieved by the current sampling system in this embodiment can also refer to the above embodiments, and this embodiment will not elaborate on them further.

[0072] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A current sampling circuit, characterized in that, The circuit includes: a sampling module, a gating module, and a control module, wherein the sampling module is provided with at least two sampling units connected in series; The sampling module is connected to the device under test and the gating module, respectively, and the control module is connected to the device under test and the gating module, respectively. The control module is used to acquire the current information of the device under test and transmit a gating signal to the gating module according to the current information; The gating module is used to select a target sampling unit from the sampling module to sample the current to be measured transmitted by the device under test according to the gating signal; the sampling module is used to generate a corresponding potential difference signal according to the current to be measured, and transmit the potential difference signal to the control module through the gating module.

2. The circuit as described in claim 1, characterized in that, The sampling unit includes: Sampling resistor, balancing capacitor, and bypass switch; The first end of the sampling resistor is connected to the first end of the balancing capacitor, the first end of the bypass switch, the device under test, and the gating module, respectively. The second end of the sampling resistor is connected to the second end of the balancing capacitor, the second end of the bypass switch, and the gating module, respectively.

3. The circuit as described in claim 1, characterized in that, The gating module includes: a potential acquisition unit and a channel selection unit; The input terminal of the potential acquisition unit is connected to the nodes of each sampling unit in the sampling module to acquire the potential difference signal of each node. The channel selection unit is connected to the output terminal of the potential acquisition unit and the control module, respectively. The channel selection unit is used to select the potential difference signal corresponding to the target sampling unit from the potential difference signals of each node according to the gating signal, and output the potential difference signal to the control module.

4. The circuit as described in claim 1, characterized in that, The control module includes: an information acquisition unit, a signal generation unit, and a signal receiving unit; The information acquisition unit is connected to the device under test and is used to acquire the current information of the device under test; The signal generation unit is connected to the information acquisition unit and is used to generate the gating signal according to the current information and transmit the gating signal to the gating module. The signal receiving unit is connected to the gating module and is used to receive the potential difference signal transmitted by the gating module.

5. The circuit as described in claim 3, characterized in that, The potential acquisition unit includes at least three voltage followers; The input terminal of the voltage follower is connected to the node of each sampling unit in the sampling module, and the output terminal of the voltage follower is connected to the channel selection unit.

6. The circuit as described in claim 1, characterized in that, The circuit also includes a signal: a signal conditioning module; The signal conditioning module is connected between the gating module and the control module and is used to amplify the potential difference signal.

7. The circuit as described in claim 6, characterized in that, The circuit also includes: a direction switching module; The direction switching is connected between the gating module and the signal conditioning module, and is used to switch the polarity of the potential difference signal input to the signal conditioning module according to the direction of the current to be measured.

8. The circuit as described in claim 6, characterized in that, The signal conditioning module includes: an instrumentation amplifier; The differential input terminal of the instrumentation amplifier is connected to the gating module to receive the potential difference signal; The output terminal of the instrumentation amplifier is connected to the control module, and is used to transmit the amplified potential difference signal to the control module.

9. The circuit as described in claim 7, characterized in that, The direction switching module includes: a single-pole double-throw switch unit; The single-pole double-throw switch unit is connected between the gating module and the signal conditioning module, and is used to change the differential polarity of the potential difference signal input to the signal conditioning module by switching the physical connection path.

10. A current sampling system, characterized in that, The current sampling system includes the current sampling circuit according to any one of claims 1 to 9.

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