Analog signal processing equipment and testing system

Abstract

This application relates to the technical field of vehicle-mounted signal testing, and in particular to an analog signal processing device and testing system. The device includes a carrier board, a gain module, an impedance matching module, and a reference ground switching module, wherein: the impedance matching module is connected to the positive and negative input terminals of the gain module; the impedance matching module is used to switch differential positive and differential negative signals to a target input path with the same impedance in response to a control signal, and input them to the gain module; the gain module is used to amplify the input differential positive and differential negative signals and output them; the reference ground switching module is connected to the gain module and the impedance matching module; the reference ground switching module is used to switch the connection between the on-board reference ground and the reference reference ground; the on-board reference ground is the reference ground of the analog signal carrier board; the gain module, impedance matching module, and reference ground switching module are all connected on the carrier board. The solution of this application can reduce the error of the processed analog signal.

Description

Technical Field

[0001] This application relates to the technical field of vehicle signal testing, and in particular to an analog signal processing device and testing system. Background Technology

[0002] HIL (Hardware-in-the-loop) testing is a testing method that combines real hardware with real-time simulation models and is currently widely used in automotive testing scenarios. HIL testing typically uses an NI chassis and a test board set; the NI chassis simulates automotive equipment or automotive electrical systems and can output corresponding status signals, while the test board set is used for signal transmission between the NI chassis and the automotive ECU (Hardware-in-the-loop Electronic Control Unit).

[0003] The interaction between the NI chassis and the ECU involves both digital and analog signal exchanges. Analog processing boards, which process analog signals, are primarily used to adjust the voltage signals input from the NI chassis to the range applicable to the ECU. However, analog signals are inherently susceptible to interference; furthermore, the scenarios and operating conditions in automotive testing are particularly complex, making them more prone to introducing interference. A significant source of interference is the issue of the reference ground during analog signal processing. Due to certain interferences, the reference ground provided on the analog processing board may not maintain a zero potential, leading to substantial errors in the processing of analog signals and consequently, unreliable test results.

[0004] Therefore, how to reduce the error of analog signals and thus improve the reliability of test results is an urgent problem to be solved. Summary of the Invention

[0005] Therefore, it is necessary to provide an analog signal processing device and testing system that can reduce the error of analog signals.

[0006] In a first aspect, this application provides an analog signal processing device, which includes a carrier board, a gain module, an impedance matching module, and a reference ground switching module, wherein:

[0007] The impedance matching module is connected to the positive and negative input terminals of the gain module.

[0008] The impedance matching module is used to switch the differential positive signal and the differential negative signal to a target input path with the same impedance in response to a control signal, and input them to the gain module.

[0009] The gain module is used to amplify the input differential positive signal and the differential negative signal before outputting them;

[0010] The reference ground switching module is connected to the gain module and the impedance matching module. The reference ground switching module is used to switch the connection between the on-board reference ground and the reference reference ground. The on-board reference ground is the reference ground of the carrier board.

[0011] The gain module, the impedance matching module, and the reference ground switching module are all connected on the carrier board.

[0012] In one embodiment, the reference ground switching module includes a switching switch and a first reference point and a second reference point disposed on the carrier board, wherein:

[0013] The first reference point is connected to the ground plane of the carrier plate; the second reference point is used to connect to an external zero potential point.

[0014] The first end of the switching switch is connected to the impedance matching module and the gain module, and the second end of the switching switch is used to switch between the first reference point and the second reference point.

[0015] In one embodiment, the gain module includes a differential amplifier, a filter module, and a reference resistor, wherein:

[0016] The positive and negative input terminals of the differential amplifier are both connected to the impedance matching module, and the output terminal of the differential amplifier is connected to the filtering module.

[0017] One end of the reference resistor is connected to the positive input terminal of the differential amplifier, and the other end is connected to the reference ground switching module.

[0018] In one embodiment, the impedance matching module includes a first matching resistor, a second matching resistor, an electromagnetic relay, and a switching transistor, wherein:

[0019] The first normally open contact of the electromagnetic relay is used to input a differential negative signal, and the second terminal is connected in series with the negative input terminal of the differential amplifier by a first matching resistor; the first normally open contact of the electromagnetic relay is used to input a differential positive signal, and the second terminal is connected in series with the positive input terminal of the differential amplifier by a first matching resistor.

[0020] The first normally closed contact of the electromagnetic relay is used to input a differential positive signal, and the second terminal is connected in series with the negative input terminal of the differential amplifier by a second matching resistor; the first terminal of the second normally closed contact of the electromagnetic relay is used to input a differential negative signal, and the second matching resistor is connected in series with the positive input terminal of the differential amplifier.

[0021] The base of the switching transistor is used to input a high-level or low-level control signal. The collector of the switching transistor is connected to the first end of the coil of the electromagnetic relay. The second end of the coil of the electromagnetic relay is connected to the first power supply terminal. The emitter of the switching transistor is connected to the first end of the switching switch.

[0022] In one embodiment, a first filter capacitor is connected in parallel across both ends of each of the first matching resistors and each of the second matching resistors.

[0023] In one embodiment, a second filter capacitor is connected in series between both the positive and negative power supply terminals of the differential amplifier and the first terminal of the switching switch.

[0024] In one embodiment, the device further includes a negative feedback resistor connected in series between the output and negative input of the differential amplifier.

[0025] In one embodiment, both the positive and negative input terminals of the differential amplifier are connected to a balancing potential module, which is used to provide a balancing potential.

[0026] In one embodiment, the balancing potential module includes a first diode and a second diode;

[0027] The cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is connected to a negative voltage, and the cathode of the second diode is connected to a positive voltage;

[0028] The cathode of the first diode is connected to either the positive or negative input terminal of the differential amplifier.

[0029] Secondly, this application provides a test system, the system comprising an NI chassis, a backplane, a power board, and an analog signal processing device as described in any one of the first aspects, wherein:

[0030] The analog signal processing device and the power supply board are both connected via a backplane, and the power supply board is used to supply power to the analog signal processing device.

[0031] The NI chassis is used to provide analog differential signals to the input of the analog signal processing device, and the output of the analog signal processing device is connected to the ECU under test.

[0032] In the aforementioned analog signal processing equipment and testing system, the impedance matching module, in response to a control signal, switches the differential positive signal and differential negative signal to a target input path with the same impedance and inputs them to the gain module. This ensures that the differential positive signal and differential negative signal have the same impedance when input, thereby reducing interference and errors introduced between the two signals. The differential gain module can subtract the input differential positive signal and differential negative signal and then gain the result to obtain the final output analog signal.

[0033] The reference ground switching module provides two reference grounds for the impedance matching and gain modules: an on-board reference ground provided by the carrier board, and an externally connected reference ground. When there is significant interference in the environment, users can connect the impedance matching and gain modules to the reference ground using the reference ground switching module. Users can then connect their desired target potential to the reference ground, thus meeting their actual needs and reducing the errors and interference caused by the instability of the on-board reference ground on the analog signal. In a more stable environment with less interference, users can omit the potential for the reference ground and connect the impedance matching and gain modules to the on-board reference ground directly using the carrier board's reference ground layer to provide zero potential, which is more convenient. Attached Figure Description

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a simplified schematic diagram of the structure of an analog signal processing device in one embodiment;

[0036] Figure 2 This is a schematic diagram of the gain module in one embodiment;

[0037] Figure 3 This is a schematic diagram of the impedance matching module in one embodiment. Detailed Implementation

[0038] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0040] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0041] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0042] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0043] When used herein, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0044] In one exemplary embodiment, this application provides an analog signal processing device that can amplify (amplify or reduce) an input analog signal so that the final output amplified analog signal can meet the voltage range requirements of the signal receiving end (such as a host computer).

[0045] Furthermore, the analog signal processing device in this application can be applied in actual detection scenarios; for example, it can be configured in a car. The input end of the analog signal processing device is connected to the output end of the analog signal sensor and receives the analog signal output by the analog signal sensor. After performing gain processing on the analog signal, the analog signal processing device outputs it to the vehicle ECU (Electronic Control Unit). The analog signal sensors in the car include, but are not limited to, wheel speed sensors, acceleration sensors, current sensors, voltage sensors, and pressure sensors.

[0046] The analog signal processing device in this application can also be applied to scenarios of HIL (Hardware-in-the-Loop) testing of automobiles; for example, the input terminal of the analog signal processing device is connected to the output terminal of the NI chassis, which is used to output analog signals simulating the status of various parts / equipment of the automobile. The analog signal processing device receives the analog signals output by the analog signal sensor, performs gain processing on the analog signals, and outputs them to the vehicle ECU (Electronic Control Unit).

[0047] Reference Figure 1 The analog signal processing device provided in this application may specifically include a carrier board, a gain module, an impedance matching module, and a reference ground switching module, wherein: the impedance matching module is connected to the positive and negative input terminals of the gain module; the impedance matching module is used to switch the differential positive signal and differential negative signal to the target input path with the same impedance in response to a control signal, and input them to the gain module; the gain module is used to amplify the input differential positive signal and differential negative signal and output them; the reference ground switching module is connected to the gain module and the impedance matching module, and is used to switch the connection between the on-board reference ground and the reference reference ground; the on-board reference ground is the reference ground of the carrier board; the gain module, the impedance matching module, and the reference ground switching module are all connected on the carrier board.

[0048] In this embodiment, the analog signal input to the differential gain module is a differential signal, which includes a differential positive signal and a differential negative signal. The differential positive and negative signals are input to the input terminal of the differential gain module through an impedance matching module. Specifically, the impedance matching module provides at least two positive paths for the differential positive signal to be input to the positive input terminal of the differential gain module, and at least two negative paths for the differential negative signal to be input to the negative input terminal of the differential gain module. The positive and negative paths are symmetrically arranged, so that each positive path corresponds to a negative path with the same impedance. In response to a control signal, the impedance matching module switches the differential positive and differential negative signals to target input paths with the same impedance and inputs them to the gain module, thereby ensuring that the differential positive and differential negative signals have the same impedance when input, thus reducing interference and error introduction between the two signals. The differential gain module can subtract the input differential positive and differential negative signals and then gain them to obtain the final output analog signal.

[0049] The reference ground switching module provides two reference grounds for the impedance matching and gain modules: an on-board reference ground provided by the carrier board, and an externally connected reference ground. When there is significant interference in the environment, users can connect the impedance matching and gain modules to the reference ground using the reference ground switching module. Users can then connect the reference ground to their desired target potential, thus meeting their actual needs and reducing the errors and interference caused by the instability of the on-board reference ground on the analog signal. In a more stable environment with less interference, users can omit the reference ground connection and connect the impedance matching and gain modules to the on-board reference ground via the reference ground switching module, directly utilizing the carrier board's ground plane to provide zero potential, which is more convenient.

[0050] In one exemplary embodiment, such as Figure 1 As shown, the reference ground switching module includes a switching switch K1 and a first reference point CK1 and a second reference point CK2 disposed on the carrier board, wherein: the first reference point CK1 is connected to the ground plane of the carrier board; the second reference point CK2 is used to connect to an external zero potential point; the first end of the switching switch is connected to the impedance matching module and the gain module, and the second end of the switching switch is used to switch between the first reference point and the second reference point.

[0051] Specifically, the changeover switch K1 can be a single-pole double-throw switch, a push-button switch, or any other type of changeover switch or component, as long as it can achieve the effect of switching between the first reference point CK1 and the second reference point CK2. The carrier board typically uses a 6-layer or 4-layer PCB structure, and its layer structure includes at least one preset ground plane to provide a zero potential (GND-1) for the chips or components mounted on the board. The first reference point CK1 is connected to the ground plane of the carrier board.

[0052] The second reference point CK2 is left floating. It can be configured as a terminal interface fixed to the carrier board or a floating pin. Users can connect their custom target potential GND-2 through the second reference point CK2. It should be noted that the target potential can be zero or a non-zero potential; users can choose according to their actual needs.

[0053] In one embodiment, Figure 2 As shown, the gain module may specifically include a differential amplifier U1, a filter module, and a reference resistor R0, wherein: the positive and negative input terminals of the differential amplifier U1 are both connected to the impedance matching module, and the output terminal of the differential amplifier U1 is connected to the filter module; one end of the reference resistor R0 is connected to the positive input terminal of the differential amplifier U1, and the other end is connected to the reference ground switching module.

[0054] Specifically, the positive input terminal of differential amplifier U1 is used to input a differential positive signal, and the negative input terminal is used to input a differential negative signal. The positive power supply terminal of differential amplifier U1 is connected to an externally input positive voltage, and the negative power supply terminal is connected to an externally input negative voltage. Furthermore, to maintain stable power supply to differential amplifier U1, a filter capacitor C1 is connected in series at both the positive and negative power supply terminals. One end of one filter capacitor C1 is connected to the positive power supply terminal of differential amplifier U1, and the other end is grounded; one end of the other filter capacitor C1 is connected to the negative power supply terminal of differential amplifier U1, and the other end is grounded. The grounded filter capacitor C1 is connected to the first terminal of the switching switch in the reference ground switching module. When the power supply voltage of differential amplifier U1 decreases, the filter capacitor C1 can discharge, thereby keeping the power supply voltage of differential amplifier U1 stable and reducing interference caused by power supply voltage fluctuations to signal processing.

[0055] Furthermore, referring to Figure 2 The differential amplifier U1 outputs a gain signal after differential gain and feeds this gain signal back to the ECU. The filtering module is used to filter the gain signal output by the differential amplifier U1 to obtain a more stable gain signal. In other words, the filtering module makes the gain signal fed back to the ECU by the differential amplifier U1 more stable and less interfered with. The filtering module specifically includes a resistor R3 and a capacitor C4. The first end of the resistor R3 is connected to the output terminal of the differential amplifier U1, and the second end of the resistor R3 is used to output an analog signal. The first end of the capacitor C4 is connected to the second end of the resistor R3, and the second end of the capacitor C4 is connected to the first end of the switch K1 for grounding.

[0056] Furthermore, referring to Figure 2A capacitor C2 is connected in parallel across the reference resistor R0. On one hand, the reference resistor R0 and capacitor C2 form an RC oscillation circuit, thereby filtering the signal input to the positive input terminal of the differential amplifier U1. On the other hand, the ratio of the resistance of the reference capacitor R0 to the equivalent resistance of the input impedance connected to the positive input terminal of the differential amplifier U1 is the amplification factor of the gain amplifier U1. In other words, with a fixed input impedance connected to the positive input terminal of the differential amplifier U1, the amplification factor of the differential amplifier U1 can be adjusted by changing the resistance of the reference capacitor R0. Therefore, in one possible implementation, the reference resistor R0 can also be replaced with a digital potentiometer. A digital potentiometer can be controlled by adjusting a digital signal, thereby changing its equivalent resistance. When the reference resistor R0 is a digital potentiometer, the user can output a corresponding digital signal to the digital potentiometer through the NI chassis or ECU, thereby changing the equivalent resistance of the digital potentiometer. This allows for relatively convenient adjustment of the amplification factor of the differential amplifier U1.

[0057] In one embodiment, reference Figure 2 The device also includes a negative feedback resistor RF, which is connected in series between the output and negative input terminals of the differential amplifier U1 to achieve closed-loop feedback. Furthermore, a capacitor C5 is connected in parallel across the negative feedback resistor RF. On one hand, the negative feedback resistor RF further filters out common-mode noise in the circuit through a high common-mode rejection ratio, thereby eliminating common-mode interference. On the other hand, the closed-loop negative feedback mechanism effectively reduces the output impedance of the differential amplifier U1, thus avoiding signal attenuation caused by the load effect of subsequent circuits (such as an ADC or long cables).

[0058] In one embodiment, reference Figure 3 The impedance matching module includes a first matching resistor R1, a second matching resistor R2, an electromagnetic relay KM, and a switching transistor Q1. Specifically, the first normally open contact KM-1 of the electromagnetic relay KM is used to input a differential negative signal, and the second terminal is connected in series with the negative input terminal of the differential amplifier U1 via a first matching resistor R1. The first normally open contact KM-2 of the electromagnetic relay KM is used to input a differential positive signal, and the second terminal is connected in series with the positive input terminal of the differential amplifier U1 via a first matching resistor R1. The first normally closed contact KM-3 of the electromagnetic relay KM is used to input a differential positive signal, and the second terminal is connected in series with the negative input terminal of the differential amplifier U1 via a second matching resistor R2. The first normally closed contact KM-4 of the electromagnetic relay KM is used to input a differential negative signal, and the second terminal is connected in series with the positive input terminal of the differential amplifier U1 via a second matching resistor R2.

[0059] The base of the switching transistor Q1 is used to input a high-level or low-level control signal. The collector of the switching transistor Q1 is connected to the first terminal of the coil of the electromagnetic relay KM. The second terminal of the coil of the electromagnetic relay KM is used to input the power supply voltage. The emitter of the switching transistor Q1 is connected to the first terminal of the switching switch K1.

[0060] Specifically, when the control signal input to the base of the switching transistor Q1 is low, the collector of the switching transistor Q1 is not conducting to the emitter. Therefore, the power supply circuit of the coil of the electromagnetic relay KM cannot be connected, and the coil of the electromagnetic relay KM cannot be energized. As a result, the first normally open contact KM-1 and the second normally open contact KM-2 of the electromagnetic relay KM are both open, while the first field-closed contact KM-3 and the second normally closed contact KM-4 of the electromagnetic relay KM are both closed. This allows the differential positive signal to be input to the positive input terminal of the differential amplifier U1 through the second matching resistor R2, and the differential negative signal to be input to the negative input terminal of the differential amplifier U1 through another second matching resistor R2.

[0061] Specifically, refer to Figure 2 and Figure 3 A protective resistor R5 is connected to the base of the switching transistor Q1. The externally output control signal is input to the base of the switching transistor Q1 through the protective resistor R5. The protective resistor limits the current input to the base of the switching transistor Q1, thus protecting the component. A pull-down resistor R6 is connected in series between the base and emitter of the switching transistor Q1. Since the collector of the switching transistor Q1 only conducts to the emitter when the base receives a high-level control signal, a default low level needs to be set for the base of the switching transistor Q1 when it is not conducting. This default low level is provided by the pull-down resistor R6.

[0062] Furthermore, referring to Figure 2 and Figure 3 An overcurrent diode D0 is connected in parallel across the two ends of the electromagnetic relay KM. A resistor R7 is connected to the second end of the electromagnetic relay KM, which limits the current in the coil of the electromagnetic relay KM to provide overcurrent protection. The anode of the overcurrent diode D0 is connected to the first end of the coil of the electromagnetic relay KM, and the cathode is connected to the second end of the coil of the electromagnetic relay KM. When the coil of the electromagnetic relay KM is energized, the overcurrent diode D0 does not operate. When the coil of the electromagnetic relay KM is de-energized, the overcurrent diode D0 and the coil of the electromagnetic relay KM form a closed circuit, thereby consuming the residual electrical energy in the coil.

[0063] Reference Figure 2When the control signal input to the base of the switching transistor Q1 is high, the collector of the switching transistor Q1 conducts to the emitter. Therefore, the power supply circuit of the coil of the electromagnetic relay KM is turned on, and the coil of the electromagnetic relay KM is energized. As a result, the first normally open contact KM-1 and the second normally open contact KM-2 of the electromagnetic relay KM are both switched to the closed state, while the first field-closed contact KM-3 and the second normally closed contact KM-4 of the electromagnetic relay KM are both switched to the open state. This allows the differential positive signal to be input to the positive input terminal of the differential amplifier U1 through the first matching resistor R1, and the differential negative signal to be input to the negative input terminal of the differential amplifier U1 through another first matching resistor R1.

[0064] By inputting high-level or low-level control signals as described above, the differential signal can be input to the differential amplifier U1 through the first matching resistor R1 or the second matching resistor R2, thereby achieving selection of the differential signal input impedance. Furthermore, since the two normally open contacts KM-1 and KM-2 of the electromagnetic relay KM are both connected to the first matching resistor R1, and the two normally closed contacts KM-3 and KM-4 of the electromagnetic relay KM are both connected to the second matching resistor R2, the two normally closed contacts can be synchronously turned on or off, and the two normally open contacts can also be synchronously turned on or off, thus ensuring that the input impedances of the differential positive signal and the differential negative signal remain consistent.

[0065] Furthermore, a first filter capacitor C3 is connected in parallel across each of the first matching resistor R1 and each of the second matching resistor R2; thus, regardless of which matching resistor the differential positive signal and differential negative signal are input to the differential amplifier U1, filtering can be achieved once, which can keep the differential positive signal and differential negative signal input to the differential amplifier U1 stable.

[0066] In one embodiment, reference Figure 3 The differential amplifier has a balancing potential module connected to both its positive and negative input terminals. This module provides a balancing potential. The balancing potential module serves at least four purposes, which are explained below.

[0067] The first function is that the virtual short effect of the differential amplifier U1 forces the potentials of the two input terminals to be equal, ensuring that common-mode signals (such as noise or interference) are canceled at the input terminals, and only the differential-mode signals are amplified; the setting of the balancing potential module can improve the circuit's ability to suppress common-mode interference and enhance the signal-to-noise ratio of the signal.

[0068] The second function is that, under the condition of virtual short, the voltage difference at the input of differential amplifier U1 is determined only by the differential mode signal. The presence of the balancing potential module can avoid the error introduced by the common mode voltage. At the same time, combined with negative feedback, differential amplifier U1 can accurately amplify the useful signal.

[0069] The third function is that the virtual open circuit characteristic of the differential amplifier U1 makes the input current approach zero, and the impedance seen from the signal source is extremely high. This reduces the load effect on the high impedance signal source and can ensure the accuracy of signal acquisition.

[0070] The fourth function is that the balanced potential modules connected to the two input terminals of the differential amplifier U1 can be designed symmetrically in physical layout, reducing the differential influence of external electromagnetic interference and further improving noise immunity.

[0071] Specifically, the balancing potential module includes a first diode D1 and a second diode D2; wherein, the cathode of the first diode D1 is connected to the anode of the second diode D2, the anode of the first diode D1 is connected to a negative voltage, and the cathode of the second diode D2 is connected to a positive voltage; the cathode of the first diode D1 is connected to either the positive or negative input terminal of the differential amplifier U1.

[0072] It is understood that the above-mentioned balancing potential module and impedance matching module can also take other forms, and are not limited to the forms mentioned in the above embodiments, as long as they can achieve the functions of completing the corresponding reference potential and switching and matching the input impedance of the differential signal.

[0073] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0074] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An analog signal processing device, characterized in that, The device includes a carrier board, a gain module, an impedance matching module, and a reference ground switching module, wherein: The impedance matching module is connected to the positive and negative input terminals of the gain module. The impedance matching module is used to switch the differential positive signal and the differential negative signal to a target input path with the same impedance in response to a control signal, and input them to the gain module. The gain module is used to amplify the input differential positive signal and the differential negative signal before outputting them; The reference ground switching module is connected to the gain module and the impedance matching module. The reference ground switching module is used to switch the connection between the on-board reference ground and the reference reference ground. The on-board reference ground is the reference ground of the carrier board. The gain module, the impedance matching module, and the reference ground switching module are all connected on the carrier board.

2. The analog signal processing device according to claim 1, characterized in that, The reference ground switching module includes a switching switch and a first reference point and a second reference point disposed on the carrier plate, wherein: The first reference point is connected to the ground plane of the carrier plate; the second reference point is used to connect to an external zero potential point. The first end of the switching switch is connected to the impedance matching module and the gain module, and the second end of the switching switch is used to switch between the first reference point and the second reference point.

3. The analog signal processing device according to claim 2, characterized in that, The gain module includes a differential amplifier, a filter module, and a reference resistor, wherein: The positive and negative input terminals of the differential amplifier are both connected to the impedance matching module, and the output terminal of the differential amplifier is connected to the filtering module. One end of the reference resistor is connected to the positive input terminal of the differential amplifier, and the other end is connected to the reference ground switching module.

4. The analog signal processing device according to claim 3, characterized in that, The impedance matching module includes a first matching resistor, a second matching resistor, an electromagnetic relay, and a switching transistor, wherein: The first normally open contact of the electromagnetic relay is used to input a differential negative signal, and the second terminal is connected in series with the negative input terminal of the differential amplifier by a first matching resistor; the first normally open contact of the electromagnetic relay is used to input a differential positive signal, and the second terminal is connected in series with the positive input terminal of the differential amplifier by a first matching resistor. The first normally closed contact of the electromagnetic relay is used to input a differential positive signal, and the second terminal is connected in series with the negative input terminal of the differential amplifier by a second matching resistor; the first terminal of the second normally closed contact of the electromagnetic relay is used to input a differential negative signal, and the second matching resistor is connected in series with the positive input terminal of the differential amplifier. The base of the switching transistor is used to input a high-level or low-level control signal. The collector of the switching transistor is connected to the first end of the coil of the electromagnetic relay. The second end of the coil of the electromagnetic relay is connected to the first power supply terminal. The emitter of the switching transistor is connected to the first end of the switching switch.

5. The analog signal processing device according to claim 4, characterized in that, A first filter capacitor is connected in parallel across both ends of each of the first matching resistors and each of the second matching resistors.

6. The analog signal processing device according to claim 4, characterized in that, A second filter capacitor is connected in series between the positive and negative power supply terminals of the differential amplifier and the first terminal of the switching switch.

7. The analog signal processing device according to claim 5, characterized in that, The device also includes a negative feedback resistor, which is connected in series between the output terminal and the negative input terminal of the differential amplifier.

8. The analog signal processing apparatus according to claim 7, characterized in that, The differential amplifier is connected to a balancing potential module at both its positive and negative input terminals. The balancing potential module is used to provide a balancing potential.

9. The analog signal processing apparatus according to claim 8, characterized in that, The balanced potential module includes a first diode and a second diode; The cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is connected to a negative voltage, and the cathode of the second diode is connected to a positive voltage; The cathode of the first diode is connected to either the positive or negative input terminal of the differential amplifier.

10. A testing system, characterized in that, The system includes an NI chassis, a backplane, a power board, and an analog signal processing device as described in any one of claims 1-9, wherein: The analog signal processing device and the power supply board are both connected via a backplane, and the power supply board is used to supply power to the analog signal processing device. The NI chassis is used to provide analog differential signals to the input of the analog signal processing device, and the output of the analog signal processing device is connected to the ECU under test.

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