Multi-gear signal smooth switching method

Abstract

The application provides a multi-gear signal smooth switching method applied to a multi-gear signal measurement system, which comprises the following steps: for two adjacent gain gears, determining a range overlap area according to a range upper limit of a high gain gear and a range lower limit of a low gain gear, wherein the range upper limit is higher than the range lower limit; setting an upper switching threshold and a lower switching threshold in the range overlap area, so that the difference between the upper switching threshold and the lower switching threshold forms a back difference window; obtaining original sampling values output by an analog-to-digital converter, converting the original sampling values into current equivalent values of a measured physical quantity dimension according to a gain coefficient of a current gear, and filtering the current equivalent values through a digital low-pass filter to obtain filtered current equivalent values as measurement values; and making a gear switching decision according to the comparison results of the current equivalent values, the upper switching threshold and the lower switching threshold.

Description

Technical Field

[0001] This application mainly relates to the field of signal measurement technology, and in particular to a method for smooth switching of multi-level signals. Background Technology

[0002] In scientific instruments and industrial measurement applications such as core power measurement, radiation detection, and precision electrometers, measurement systems typically employ a multi-gain measurement architecture. This involves setting multiple gain levels through the front-end acquisition circuit to cover different measurement ranges and automatically selecting the appropriate level based on the magnitude of the measured signal.

[0003] However, existing measurement systems have the following problems: when the magnitude of the measured signal fluctuates around a given threshold, the system will frequently switch between adjacent levels, resulting in level oscillation; and, at the moment of switching between different gain levels, the output signal is prone to sudden changes, causing the measurement data to lose its reference value during the switching period. Summary of the Invention

[0004] The purpose of this application is to provide a method for smooth switching of multi-gear signals, which can effectively reduce the signal jumps before and after gear oscillation.

[0005] In a first aspect, this application provides a method for smooth switching of multi-gain signals, applied to a multi-gain signal measurement system. The multi-gain signal measurement system includes a front-end acquisition circuit, an analog-to-digital converter (ADC), and a processor unit connected in sequence. The front-end acquisition circuit is configured with multiple different gain levels to cover different measurement ranges. These different ranges use a unified physical dimension of the measured quantity, and each gain level corresponds to a unique gain coefficient. The ADC is used to control the conversion of the analog signal output by the front-end acquisition circuit into a digital signal. The processor unit internally contains a unique digital low-pass filter. The method includes: for two adjacent gain levels, determining a range overlap region based on the upper limit of the high-gain level's range and the lower limit of the low-gain level's range, wherein the upper limit of the range is higher than the lower limit; setting an upper switching threshold and a lower switching threshold within the range overlap region, such that the upper switching threshold is equal to the lower limit of the high-gain level's range. The difference between the lower and upper switching thresholds forms a hysteresis window, wherein the upper switching threshold is higher than the lower switching threshold. The original sampled value output by the analog-to-digital converter is obtained, and according to the gain coefficient of the current gear, the original sampled value is converted into the current equivalent value of the measured physical quantity. The current equivalent value is then filtered by the digital low-pass filter, and the filtered current equivalent value is used as the measured value. A gear switching decision is made based on the comparison results between the current equivalent value and the upper and lower switching thresholds: if the current equivalent value exceeds the upper switching threshold, the current gear is controlled to switch from the high-gain gear to the low-gain gear; if the current equivalent value is lower than the lower switching threshold, the current gear is controlled to switch from the low-gain gear to the high-gain gear; if the current equivalent value is within the hysteresis window, the current gear remains unchanged.

[0006] In one embodiment of this application, the front-end acquisition circuit includes a transimpedance amplifier, and the multiple different gain levels correspond to multiple feedback resistors connected in parallel with the transimpedance amplifier. The resistance values ​​of the multiple feedback resistors are different from each other, and an analog switch is provided between each feedback resistor and the transimpedance amplifier. The processor unit controls the analog switch to select a corresponding feedback resistor to achieve level switching.

[0007] In one embodiment of this application, the number of gain levels is eight, corresponding to feedback resistors with resistance values ​​of 10GΩ, 1GΩ, 100MΩ, 10MΩ, 1MΩ, 100kΩ, 10kΩ and 1kΩ respectively.

[0008] In one embodiment of this application, the dimension is current, and the gain coefficient is proportional to the resistance value of a corresponding feedback resistor.

[0009] In one embodiment of this application, the digital low-pass filter is an infinite impulse response filter or a finite impulse response filter.

[0010] In one embodiment of this application, the digital signal is a voltage signal, and the maximum value of the digital signal is 2.5V.

[0011] In one embodiment of this application, the voltage corresponding to the upper limit of the range is not higher than 80% of the maximum output voltage of the transimpedance amplifier, and the voltage corresponding to the lower limit of the range is not lower than 4% of the maximum output voltage of the transimpedance amplifier.

[0012] In one embodiment of this application, the range of the hysteresis window is 50% to 100% of the range overlap region.

[0013] In one embodiment of this application, after making a gear shift decision based on the comparison result of the current equivalent value with the upper switching threshold and the lower switching threshold, the method further includes: determining whether the state in which the current equivalent value exceeds the upper switching threshold or is lower than the lower switching threshold has continuously reached a preset number, and whether the time elapsed since the last gear shift exceeds a preset time; if the state has continuously reached the preset number and the time elapsed since the last gear shift exceeds the preset time, then controlling the front-end acquisition circuit to switch from the current gear to the target gear, wherein, for the current gear being the high-gain gear, the target gear being the low-gain gear, and for the current gear being the low-gain gear, the target gear being the high-gain gear; otherwise, gear shifting is not performed.

[0014] In one embodiment of this application, the processor unit is any one of a microcontroller, a digital signal processor, and a field-programmable gate array (FPGA).

[0015] Compared with the prior art, the beneficial effects of this application are as follows: The technical solution of this application eliminates the problem of frequent switching between adjacent levels by using a hysteresis window design to keep the system at the current level when the signal fluctuates near the threshold. A unified dimensional conversion mechanism maps the output signals of different gain levels to the same physical quantity space, ensuring continuous equivalent values ​​before and after switching without jumps due to gain differences. By using only one digital low-pass filter within the system, the equivalent value continues to be input to the same filter after switching, allowing the historical state variables accumulated within the filter to continue naturally without needing to re-establish a steady state, resulting in a smooth output transition. Furthermore, the switching decision is based on the measured value rather than the original signal, avoiding erroneous switching triggered by noise spikes. Thus, the multi-level signal measurement system can output continuous, stable, and disturbance-free measurement data throughout the entire dynamic range, with a simple architecture requiring only one set of digital filters and eliminating the need for complex hardware soft-switching circuits.

[0016] It should be understood that the summary section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0017] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of some embodiments thereof in the accompanying drawings, in which: Figure 1 This is a schematic diagram of a multi-level signal measurement system provided in an exemplary embodiment of this application; Figure 2 This is a magnified view of the transconductance network in a multi-level signal measurement system. Figure 3 This is a flowchart of a multi-level signal measurement method provided by an exemplary embodiment of this application; Figure 4 This is one of the logical diagrams of a backflow window provided in an exemplary embodiment of this application; Figure 5 This is one of the logical diagrams of a backflow window provided in an exemplary embodiment of this application; Figure 6 This is a logical diagram of a gear shifting control provided by an exemplary embodiment of this application. Detailed Implementation

[0018] The principles of this disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not impose any limitation on the scope of this disclosure. The disclosure described herein may be implemented in ways other than those described below.

[0019] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0020] References to "an embodiment," "embodiment," "exemplary embodiment," etc., in this disclosure indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment needs to include specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an exemplary embodiment, whether explicitly described or not, those skilled in the art will recognize that such a feature, structure, or characteristic affects its connection to other embodiments.

[0021] It should be understood that while the terms “first” and “second”, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term “and / or” as used herein includes any and all combinations of one or more of the listed terms.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. The singular forms “a,” “an,” and “the” used herein also include the plural forms unless the context clearly indicates otherwise. The terms “a group of elements” or “a collection of elements” as used herein are intended to include one or more elements. It should also be understood that the terms “comprising,” “including,” “having,” “possessing,” “including,” and / or “comprising,” when used herein, specify the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0023] This application provides a multi-range signal measurement method, which is applied to a multi-range signal measurement system. This system can be used for various wide-range signal measurement scenarios such as current measurement, voltage measurement, and optical power measurement, requiring only adjustments to the type of physical quantity and gain coefficient for dimension conversion. For ease of description, the following embodiments use current measurement (i.e., the measured physical quantity is current) as an example.

[0024] The following is combined with Figure 1 and Figure 2 A brief introduction to the hardware configuration of a multi-level signal measurement system is provided. For example... Figure 1As shown, the multi-gain signal measurement system includes a front-end acquisition circuit 10, an analog-to-digital converter (ADC) 20, and a processor unit 30 connected in sequence. Specifically, the front-end acquisition circuit 10 is located at the signal input terminal of the measurement system, used to receive external measured signals and convert them into analog signals. The front-end acquisition circuit 10 has multiple different gain levels to cover different measurement ranges. Different ranges use a unified measured physical dimension (current), enabling the multi-gain signal measurement system to maintain effective measurement over a wide dynamic range. The ADC 20 is connected to the output terminal of the front-end acquisition circuit 10, used to convert the analog signal output by the front-end acquisition circuit 10 into a digital signal. The processor unit 30 is connected to the output terminal of the ADC 20, used to perform dimension conversion, threshold determination, level switching control, and digital low-pass filtering on the digital signal. The digital low-pass filtering is implemented by a digital low-pass filter internally configured in the processor unit 30. Optionally, the output terminal of the processor unit 30 is also connected to a digital-to-analog converter (DAC) 40, used to convert the digital signal into an analog signal.

[0025] In some embodiments, the front-end acquisition circuit 10 includes a transimpedance amplifier 101, and multiple different gain levels correspond to multiple feedback resistors connected in parallel with the transimpedance amplifier 101. Figure 1 The example shows feedback resistors R1-R8, each with a different resistance value. Figure 2 This is a magnified view of a portion of the transconductance network (i.e., the transimpedance amplifier feedback network) in the front-end acquisition circuit 10. (Reference) Figure 2 The processor unit 30 controls the analog switch 102 ( Figure 1 An example is shown where the analog switch 102 corresponding to the feedback resistor R1 selects a corresponding feedback resistor to achieve range switching. Specifically, in a multi-range signal measurement system, the analog switch 102 is an electronic switching device controlled by the processor unit 30. In practical applications, the processor unit 30 controls the corresponding analog switch 102 to close according to a selected gain range, thereby selecting the feedback loop of the feedback resistor corresponding to that gain range and the transimpedance amplifier 101. At this time, the feedback loops of the feedback resistors corresponding to other gain ranges and the transimpedance amplifier 101 are all disconnected, thus ensuring that only one gain range operates at a time. The embodiments of this application use an analog switch selection method to achieve range switching, which has the advantages of fast response speed, no contact wear, and small size compared with the traditional mechanical relay switching method.

[0026] In some embodiments, there are eight gain levels, corresponding to feedback resistors with resistance values ​​of 10GΩ, 1GΩ, 100MΩ, 10MΩ, 1MΩ, 100kΩ, 10kΩ, and 1kΩ, respectively. For example, the eight gain levels are defined as levels 1 to 8, and the corresponding feedback resistors are defined as R8 to R1 (R8 is 10GΩ, R7 is 1GΩ, and so on).

[0027] In some embodiments, the analog-to-digital converter 20 converts the analog signal output by the front-end acquisition circuit 10 into a digital signal. In the current measurement shown in this embodiment, the output terminal of the front-end acquisition circuit 10 is the output terminal of the transimpedance amplifier 101 (i.e., Figure 1 The output terminal of the transimpedance amplifier 101 is connected to the input terminal of the analog-to-digital converter 20 (out terminal). Therefore, the analog signal is the voltage signal at the output terminal of the transimpedance amplifier 101. Since R1~R8 are connected in parallel with the transimpedance amplifier 101, the analog signal is the voltage signal at the output terminal of the transimpedance amplifier 101. Figure 1 In the multi-level signal measurement system shown, the larger the resistance value of the feedback resistor, the higher the gain of the signal; that is, the gain coefficient is proportional to the resistance value of the corresponding feedback resistor.

[0028] In some embodiments, the analog-to-digital converter 20 can be a 24-bit Σ-Δ analog-to-digital converter 20. The Σ-Δ analog-to-digital converter 20 features high resolution and low noise, making it suitable for high-precision acquisition of weak signals.

[0029] In some embodiments, the processor unit 30 is any one of a microcontroller (MCU), a digital signal processor (DSP), and a field-programmable gate array (FPGA). MCUs are suitable for general embedded scenarios, DSPs are suitable for high-speed signal processing scenarios, and FPGAs are suitable for parallel processing and low-latency scenarios. This embodiment uses a microcontroller as an example.

[0030] Figure 3 This is a flowchart of a method for smooth switching of multi-level signals provided in this application. In a specific implementation, steps S1 to S4 in the flowchart are... Figure 1 The processor unit 30 in the processor is the main execution unit. For example... Figure 3 As shown, the method for smooth switching of multi-level signals includes: Step S1: Determine the range overlap area based on the upper limit of the high gain range and the lower limit of the low gain range, wherein the upper limit of the range is higher than the lower limit of the range.

[0031] Specifically, the range refers to the effective measurement range of a multi-gain signal measurement system at a certain gain level. The upper and lower limits of the range are the upper and lower boundaries of the effective measurement range, respectively.

[0032] Taking gain level 2 (R7=1GΩ, high gain level) and gain level 3 (R6=100MΩ, low gain level) as examples, when the front-end acquisition circuit is switched to gain level 2, the effective measurement range is 0.1nA-2nA. When the front-end acquisition circuit is switched to gain level 3, the effective measurement range is 1nA-20nA. It can be seen that the upper limit of the high gain level is 2nA, and the lower limit of the low gain level is 1nA. Gain levels 2 and 3 overlap in the 1nA to 2nA range, meaning the range overlap area is 1nA-2nA.

[0033] In some embodiments, the voltage corresponding to the upper limit of the range is no higher than 80% of the maximum output voltage of the transimpedance amplifier, and the voltage corresponding to the lower limit of the range is no lower than 4% of the maximum output voltage of the transimpedance amplifier. In the example above, the maximum output voltage of the transimpedance amplifier is 2.5V. The advantage of this is that by reserving transient margin for each gain range, the signal in the range overlap region is within the effective measurement range in both ranges, thereby providing a high-quality judgment space for subsequent switching decision hysteresis.

[0034] Step S2: Set an upper switching threshold and a lower switching threshold within the range overlap area, so that the difference between the upper switching threshold and the lower switching threshold forms a hysteresis window, wherein the upper switching threshold is higher than the lower switching threshold.

[0035] Specifically, the upper switching threshold refers to the trigger threshold value for switching from a high gain level to a low gain level, and the lower switching threshold refers to the trigger threshold value for switching from a low gain level to a high gain level. The interval formed by the difference between the two is the hysteresis window.

[0036] In some embodiments, the hysteresis window ranges from 50% to 100% of the range overlap area.

[0037] like Figure 4 and Figure 5 As shown, taking gain level 2 (R7=1GΩ, high gain level) and gain level 3 (R6=100MΩ, low gain level) as examples, in step S2, the upper switching threshold is 1.8nA, the lower switching threshold is 1.2nA, and the hysteresis window is 1.2nA-1.8nA (range of 0.6nA), which accounts for 60% of the range overlap area.

[0038] According to Ohm's law, the upper switching threshold is 1.8nA, corresponding to a sampling voltage of 1.8V in the high gain setting; the lower switching threshold is 1.2nA, corresponding to a sampling voltage of 0.12V in the low gain setting.

[0039] In a multi-gain signal measurement system, each group of adjacent gain levels can be set with a dedicated hysteresis window. The proportions of these hysteresis windows in the range overlap area can be the same or different, and there is no restriction on this.

[0040] Step S3: Obtain the original sampled value output by the analog-to-digital converter, convert the original sampled value into the current equivalent value of the measured physical quantity according to the gain coefficient of the current range, and filter the current equivalent value through a digital low-pass filter, and use the filtered current equivalent value as the measurement value.

[0041] Taking gain level 2 (R7=1GΩ, high gain level) and gain level 3 (R6=100MΩ, low gain level) as examples, if the current level is gain level 3, the gain coefficient of gain level 3 (R6=100MΩ) is called to complete the dimension conversion. If the current level is gain level 2, the gain coefficient of gain level 2 (R7=1GΩ) is called to complete the dimension conversion. The unit of the current equivalent value can be uniformly set to nA.

[0042] The current equivalent value is filtered by a digital low-pass filter, which is the only filter in the multi-level signal measurement system. The cutoff frequency of the filter is set according to the target signal bandwidth (typically 10Hz).

[0043] Taking a second-order Butterworth IIR low-pass filter as an example, the current equivalent value after filtering satisfies: y[n] = b0 x[n] + b1 x[n-1] + b2 x[n-2] - a1 y[n-1] - a2 y[n-2] Where x[n] is the current equivalent value after converting the original sampled value into current, y[n] is the current equivalent value after filtering, i.e. the measured value; y[n-1] and y[n-2] are historical measured values, x[n-1] is the historical equivalent value, and b0, b1, b2, a1, and a2 are preset coefficients.

[0044] As can be seen from the above formula, the digital low-pass filter continuously maintains a set of historical variables during operation and does not perform a clearing operation when switching gears. At the same time, the digital low-pass filter is unique (the only filter that performs the signal filtering function in a multi-gear signal measurement system). Therefore, no matter how the current gear is switched, each current equivalent value is uniformly sent to the digital low-pass filter, so that the historical state variables accumulated inside the filter continue naturally before and after the gear switching, without the need to re-establish a steady state, ensuring that the output signal has no transition process.

[0045] Step S4: Make a gear switching decision based on the comparison results of the current equivalent value with the upper switching threshold and the lower switching threshold: when the current equivalent value exceeds the upper switching threshold, control the current gear to switch from the high gain gear to the low gain gear; when the current equivalent value is lower than the lower switching threshold, control the current gear to switch from the low gain gear to the high gain gear; when the current equivalent value is within the hysteresis window, keep the current gear unchanged.

[0046] Taking gain level 2 (R7=1GΩ, high gain) and gain level 3 (R6=100MΩ, low gain) as examples, assuming the current level is gain level 2, the processor unit compares the current equivalent value with the upper switching threshold and the lower switching threshold. When the current equivalent value exceeds the upper switching threshold (1.8nA), the decision is to switch the current level from gain level 2 to gain level 3; when the current equivalent value is lower than the lower switching threshold (1.2nA), the decision is to switch the current level from gain level 3 to gain level 2; when the current equivalent value is within the hysteresis window (1.2nA-1.8nA), the decision is to keep the current level unchanged.

[0047] Existing solutions often employ a single threshold criterion. For example, when the detected current value is greater than 1.5nA, the system switches to gain level 3, and when it is less than or equal to 1.5nA, it switches to gain level 2. When the measured value fluctuates repeatedly between 1.4nA and 1.6nA, this approach causes repeated switching between gain level 2 and gain level 3, resulting in level oscillation. Compared to existing designs, the technical solution in this application incorporates a hysteresis window. Therefore, even if the current equivalent value fluctuates repeatedly between 1.4nA and 1.6nA, the processor unit can determine that the front-end acquisition circuit should remain at the current level without switching. This eliminates the oscillation phenomenon at its source and ensures the reliability of the level switching decision.

[0048] In some embodiments, after the gear shifting decision in step S4, the processor unit further performs the following steps: after making the gear shifting decision based on the comparison results of the current equivalent value with the upper shifting threshold and the lower shifting threshold, it further includes: determining whether the state where the current equivalent value exceeds the upper shifting threshold or is lower than the lower shifting threshold has continuously reached a preset number, and whether the time elapsed since the last gear shift exceeds a preset time; if the state has continuously reached the preset number and the time elapsed since the last gear shift exceeds the preset time, then the front-end acquisition circuit is controlled to switch from the current gear to the target gear, wherein the current gear is a high-gain gear and the target gear is a low-gain gear, and the current gear is a low-gain gear and the target gear is a high-gain gear; otherwise, gear shifting is not performed.

[0049] refer to Figure 6Taking gain level 2 (R7=1GΩ, high gain) and gain level 3 (R6=100MΩ, low gain) as examples, in this example, the preset quantity is 3 and the preset duration is 10ms. When the current equivalent value exceeds 1.8nA and the judgment condition mentioned above is met, the processor unit controls the front-end acquisition circuit to switch from the high gain level (gain level 2) to the low gain level (gain level 3). When the current equivalent value is lower than 1.2nA and the judgment condition mentioned above is met, the processor unit controls the front-end acquisition circuit to switch from the low gain level (gain level 3) to the high gain level (gain level 2).

[0050] The advantage of doing this is that, based on using the hysteresis window to solve the gear oscillation problem, by judging whether the state has reached the preset number of sampling periods, the problem of instantaneous signal spikes triggering erroneous switching can be further avoided. Thus, anti-shake design is achieved in both the time and space dimensions, ensuring smooth and stable signal measurement.

[0051] The technical solution of this application eliminates the problem of frequent switching between adjacent levels by using a hysteresis window design to keep the system at the current level when the signal fluctuates near the threshold. A unified dimensional conversion mechanism maps the output signals of different gain levels to the same physical quantity space, ensuring continuous equivalent values ​​before and after switching without jumps due to gain differences. By using only one digital low-pass filter within the system, the equivalent value continues to be input to the same filter after switching, allowing the historical state variables accumulated within the filter to continue naturally without needing to re-establish a steady state, resulting in a smooth output transition. Furthermore, the switching decision is based on the measured value rather than the original signal, avoiding erroneous switching triggered by noise spikes. Thus, the multi-level signal measurement system can output continuous, stable, and disturbance-free measurement data throughout the entire dynamic range, with a simple architecture requiring only one set of digital filters and eliminating the need for complex hardware soft-switching circuits.

[0052] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0053] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0054] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0055] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0056] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A method for smooth switching of multi-level signals, characterized in that, An application is made in a multi-gain signal measurement system, comprising a front-end acquisition circuit, an analog-to-digital converter, and a processor unit connected in sequence. The front-end acquisition circuit has multiple gain levels to cover different measurement ranges, each range using a unified dimension of the measured physical quantity. Each gain level corresponds to a unique gain coefficient. The analog-to-digital converter controls the conversion of the analog signal output by the front-end acquisition circuit into a digital signal. The processor unit internally contains a unique digital low-pass filter. The method includes: For two adjacent gain levels, the range overlap area is determined based on the upper limit of the range of the higher gain level and the lower limit of the range of the lower gain level, wherein the upper limit of the range is higher than the lower limit of the range. Within the range overlap region, an upper switching threshold and a lower switching threshold are set such that the difference between the upper switching threshold and the lower switching threshold forms a hysteresis window, wherein the upper switching threshold is higher than the lower switching threshold. The original sampled value output by the analog-to-digital converter is obtained. According to the gain coefficient of the current range, the original sampled value is converted into the current equivalent value of the measured physical quantity. The current equivalent value is then filtered by the digital low-pass filter, and the filtered current equivalent value is used as the measurement value. The gear shifting decision is made based on the comparison results between the current equivalent value and the upper switching threshold and the lower switching threshold: if the current equivalent value exceeds the upper switching threshold, the current gear is controlled to switch from the high gain gear to the low gain gear; if the current equivalent value is lower than the lower switching threshold, the current gear is controlled to switch from the low gain gear to the high gain gear; if the current equivalent value is within the hysteresis window, the current gear remains unchanged.

2. The method for smooth switching of multi-level signals as described in claim 1, characterized in that, The front-end acquisition circuit includes a transimpedance amplifier. The multiple different gain levels correspond to multiple feedback resistors connected in parallel with the transimpedance amplifier. The resistance values ​​of the multiple feedback resistors are different from each other. An analog switch is provided between each feedback resistor and the transimpedance amplifier. The processor unit controls the analog switch to select a corresponding feedback resistor to achieve level switching.

3. The method for smooth switching of multi-level signals as described in claim 2, characterized in that, The number of gain levels is 8, corresponding to feedback resistors with resistance values ​​of 10GΩ, 1GΩ, 100MΩ, 10MΩ, 1MΩ, 100kΩ, 10kΩ and 1kΩ respectively.

4. The method for smooth switching of multi-level signals as described in claim 2, characterized in that, The gain coefficient is proportional to the resistance value of the corresponding feedback resistor.

5. The method for smooth switching of multi-level signals as described in claim 1, characterized in that, The digital low-pass filter is an infinite impulse response filter or a finite impulse response filter.

6. The method for smooth switching of multi-level signals as described in claim 3, characterized in that, The digital signal is a voltage signal, and the maximum value of the digital signal is 2.5V.

7. The method for smooth switching of multi-level signals as described in claim 6, characterized in that, The voltage corresponding to the upper limit of the range is not higher than 80% of the maximum output voltage of the transimpedance amplifier, and the voltage corresponding to the lower limit of the range is not lower than 4% of the maximum output voltage of the transimpedance amplifier.

8. The method for smooth switching of multi-level signals as described in claim 1, characterized in that, The range of the hysteresis window is 50% to 100% of the range overlap area.

9. The method for smooth switching of multi-level signals as described in claim 1, characterized in that, After making a gear shifting decision based on the comparison results of the current equivalent value with the upper shifting threshold and the lower shifting threshold, the process further includes: Determine whether the current equivalent value exceeds the upper switching threshold or is lower than the lower switching threshold for a continuous period of time, and whether the time elapsed since the last gear shift exceeds a preset time. If the state continues to reach the preset number and the time since the last gear switch exceeds the preset time, then the front-end acquisition circuit is controlled to switch from the current gear to the target gear, wherein the current gear is the high gain gear and the target gear is the low gain gear, and the current gear is the low gain gear and the target gear is the high gain gear. Otherwise, gear shifting will not be performed.

10. The method for smooth switching of multi-level signals as described in claim 1, characterized in that, The processor unit can be any one of a microcontroller, a digital signal processor, or a field-programmable gate array (FPGA).

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