CN112290918B - Method, device and system for threshold correction of comparator - Google Patents
Method, device and system for threshold correction of comparator Download PDFInfo
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- 238000012937 correction Methods 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000005070 sampling Methods 0.000 claims abstract description 248
- 230000008859 change Effects 0.000 claims abstract description 16
- 238000001514 detection method Methods 0.000 claims description 10
- 238000005259 measurement Methods 0.000 claims description 10
- 238000012545 processing Methods 0.000 claims description 7
- 238000002603 single-photon emission computed tomography Methods 0.000 claims description 3
- 238000002600 positron emission tomography Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 238000002591 computed tomography Methods 0.000 description 3
- 238000002595 magnetic resonance imaging Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004397 blinking Effects 0.000 description 1
- 230000001364 causal effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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- 238000003384 imaging method Methods 0.000 description 1
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- 230000000750 progressive effect Effects 0.000 description 1
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- 230000002285 radioactive effect Effects 0.000 description 1
- 239000000700 radioactive tracer Substances 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/22—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral
- H03K5/24—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral the characteristic being amplitude
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
- G01T1/2914—Measurement of spatial distribution of radiation
- G01T1/2985—In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis)
Abstract
The embodiment of the application discloses a method, a device and a system for carrying out threshold correction on a comparator, wherein the method comprises the steps of reading an initial level which is output by the comparator after comparing a reference value received through a first input end on the comparator with an initial sampling threshold received through a second input end on the comparator, wherein the first input end is also used for receiving an analog signal to be sampled; the initial sampling threshold value is adjusted according to a preset change value to obtain a current sampling threshold value, and the current sampling threshold value is provided to the second input end of the comparator; reading the current level output by the comparator after comparing the reference value with the current sampling threshold; judging whether the current level is the same as the initial level, and determining a correction threshold of the comparator according to a judgment result. By utilizing the technical scheme, the automatic threshold correction of the comparator can be realized under the condition of not changing the system structure.
Description
Technical Field
The present disclosure relates to the field of data processing technologies, and in particular, to a method, an apparatus, and a system for performing threshold correction on a comparator.
Background
Positron emission tomography (Positron Emission Tomography, abbreviated as PET) is a technique for clinical imaging by using radioactive elements, and mainly captures gamma photons emitted by positron annihilation in a subject to obtain distribution of a tracer labeled with a positron nuclide in the subject, thereby obtaining physiological characteristics such as organ functions and metabolism.
At present, a Multi-sampling threshold (Multi-Voltage Threshold, abbreviated as MVT) sampling circuit is generally used for digitally sampling a pulse signal detected by a PET detector, the MVT sampling circuit mainly uses a comparator to compare the voltage of the pulse signal output by the PET detector with a preset reference voltage and output a corresponding level signal, and a time-to-digital converter is used for measuring the moment when the level signal output by the comparator turns over, so as to obtain a sampling point of the pulse signal.
When the pulse signal output by the PET detector is digitally sampled by the MVT sampling circuit, the actual voltage of the comparator turned over may not be consistent with the preset reference voltage due to the influence of various factors such as the manufacturing process of the comparator and environmental factors, so that the accuracy of the signal sampling result may be reduced, and therefore, the threshold correction of the comparator is required.
Currently, the comparator is typically thresholded using the arrangement shown in fig. 1 as follows: the pulse signal generated by the signal generator is input to one input end of the comparator, a fixed threshold value is provided to the other input end of the comparator through an analog-digital converter (DAC), the pulse width (Duration over threshold, DOT for short) of the pulse signal exceeding the fixed threshold value is measured, and the deviation between the measured DOT and the theoretical DOT is calculated to obtain a threshold value correction value of the comparator, so that the correction of the comparator is realized.
In the process of implementing the present application, the inventor finds that at least the following problems exist in the prior art:
since the threshold correction value of the comparator varies depending on the environment, the device lifetime, and the like, it is necessary to perform threshold correction again on the comparator according to actual conditions. However, in practical application, when the sampling system is built, if the threshold correction is required to be performed again on the comparator, the system structure needs to be changed to switch an input end of the comparator to be connected with the signal generator, which is troublesome and time-consuming to correct.
Disclosure of Invention
It is an object of embodiments of the present application to provide a method, apparatus and system for threshold correction of a comparator, so as to implement automatic threshold correction of the comparator without changing the system structure.
To solve the above technical problem, embodiments of the present application provide a method for performing threshold correction on a comparator, where the method may include the following steps:
reading an initial level output by the comparator after comparing a reference value received through a first input end on the comparator with an initial sampling threshold received through a second input end on the comparator, wherein the first input end is also used for receiving an analog signal to be sampled;
the initial sampling threshold value is adjusted according to a preset change value to obtain a current sampling threshold value, and the current sampling threshold value is provided to the second input end of the comparator;
reading the current level output by the comparator after comparing the reference value with the current sampling threshold;
judging whether the current level is the same as the initial level, and determining a correction threshold of the comparator according to a judgment result.
Optionally, the step of determining the correction threshold of the comparator according to the judgment result includes:
when the initial level is judged to be the same as the current level, respectively taking the current level and the current sampling threshold as the initial level and the initial sampling threshold, and repeating the steps of adjusting the initial sampling threshold and reading the current level until the current level is judged to be different from the initial level;
when the current level is judged to be different from the initial level, it is determined that a correction threshold of the comparator is located between a difference value of the initial sampling threshold and the reference value and a difference value of the current sampling threshold and the reference value.
Optionally, after determining that the correction threshold of the comparator is located between the difference between the initial sampling threshold and the reference value and the difference between the current sampling threshold and the reference value, the step of determining the correction threshold of the comparator according to the judgment result further includes:
and taking the difference value between the initial sampling threshold value and the reference value, the difference value between the current sampling threshold value and the reference value, or the average value or root mean square of the difference value between the current sampling threshold value and the reference value and the difference value between the initial sampling threshold value and the reference value as a correction threshold value of the comparator.
Optionally, after determining that the correction threshold of the comparator is between the difference of the initial sampling threshold and the reference value and the difference of the current sampling threshold and the reference value, the method further comprises:
reducing the preset change value, adjusting the initial sampling threshold value when the current level is judged to be different from the initial level according to the reduced preset change value to obtain a current sampling threshold value, and providing the obtained current sampling threshold value to the second input end;
repeating the steps of reading the current level and judging whether the current level is the same as the initial level until the current level is different from the initial level;
and when the current level is judged to be different from the initial level, determining the difference value between the initial sampling threshold value and the reference value, the difference value between the current sampling threshold value and the reference value, or the average value or the root mean square of the difference value between the current sampling threshold value and the reference value and the difference value between the initial sampling threshold value and the reference value as the correction threshold value of the comparator.
Optionally, the reference value includes a power-on voltage of a system in which the comparator is located or a voltage provided by an externally provided supply terminal.
Optionally, the initial sampling threshold is a sum of the reference value and a pre-estimated maximum or minimum sampling threshold, and the initial sampling threshold is within a range of an element connected to the second input of the comparator.
Optionally, the step of adjusting the initial sampling threshold according to a preset variation value to obtain a current sampling threshold includes:
when the initial sampling threshold value is the sum of the reference value and a pre-estimated maximum sampling threshold value, subtracting the preset change value from the initial sampling threshold value to obtain the current sampling threshold value;
and when the initial sampling threshold value is the sum of the reference value and a minimum sampling threshold value estimated in advance, adding the preset change value to the initial sampling threshold value to obtain the current sampling threshold value.
Optionally, the preset variation value is preset according to a minimum scale of an element connected to the second input terminal of the comparator.
The embodiment of the application also provides a device for performing threshold correction on the comparator, which can comprise:
a first reading unit configured to read an initial level output by the comparator after comparing a reference value received through a first input terminal thereon with an initial sampling threshold value received through a second input terminal thereon, wherein the first input terminal is further used for receiving an analog signal to be sampled;
the adjusting unit is configured to adjust the initial sampling threshold value according to a preset change value to obtain a current sampling threshold value, and provide the current sampling threshold value to the second input end of the comparator;
a second reading unit configured to read a current level output by the comparator after comparing the reference value with the current sampling threshold;
and a determining unit configured to determine whether the current level is the same as the initial level, and determine a correction threshold of the comparator according to a determination result.
Optionally, the determining unit is specifically configured to:
when the initial level is judged to be the same as the current level, respectively taking the current level and the current sampling threshold value as the initial level and the initial sampling threshold value, and indicating the adjusting unit and the second reading unit to circularly execute corresponding operations until the current level is judged to be different from the initial level;
and when the current level is judged to be different from the initial level, determining the difference value between the initial sampling threshold value and the reference value, the difference value between the current sampling threshold value and the reference value, or the average value or the root mean square of the difference value between the current sampling threshold value and the reference value and the difference value between the initial sampling threshold value and the reference value as the correction threshold value of the comparator.
The embodiment of the application also provides a signal sampling system, which can comprise the comparator and a device for carrying out threshold correction on the comparator.
Optionally, the system may further include:
a detection device is connected to the first input of the comparator to provide an analog signal to be sampled to the comparator.
Optionally, the detection device comprises an MRI device, a CT device, a SPECT device, a PET device, or a PET-CT device.
Optionally, the system further comprises:
a threshold supply means configured to provide a plurality of sampling thresholds to the comparator under control of the means, the plurality of sampling thresholds comprising an initial sampling threshold and a current sampling threshold.
Optionally, the threshold supply device comprises a digital-to-analog converter, an adjustable voltage divider circuit, or an adjustable power supply.
Optionally, the system further comprises:
and a time measurement device configured to measure a time when the analog signal reaches a preset sampling threshold value based on the level signal output from the comparator, to obtain a sampling point composed of the time and the preset sampling threshold value, the preset sampling threshold value being included in a plurality of the sampling threshold values.
Optionally, the time measurement device comprises a time to digital converter, a time to analog converter or a timer.
Optionally, the input of the time measurement device is connected in parallel with the output of the device and the comparator, or the input of the time measurement device is connected with the output of the comparator and the output of the time measurement device is connected with the device.
Optionally, the system further comprises:
and the data processing device is configured to reconstruct the obtained sampling points to obtain a restored waveform of the analog signal.
Optionally, the system may further include:
a switch disposed between the detection device and the first input of the comparator;
and a supply terminal connected to the switch to supply a reference value to the first input terminal in the form of a direct current signal.
As can be seen from the technical solutions provided in the embodiments of the present application, by determining whether an initial level obtained under an initial sampling threshold is the same as a current level obtained under a current sampling threshold obtained by adjusting the initial sampling threshold, and determining a correction threshold of a comparator according to a determination result, automatic threshold correction of the comparator is achieved, so that when an analog signal is sampled, the sampling threshold can be directly set according to the correction threshold, and no additional signal generator is required to generate a correction signal, and further after system deployment is completed, threshold correction can be directly performed on the comparator in the same manner, without changing a system structure, which can simplify operations and save correction time.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and that other drawings may be obtained according to these drawings without inventive effort to a person skilled in the art.
FIG. 1 is a schematic diagram of a prior art apparatus for threshold correction of a comparator;
FIG. 2 is a flow chart of a method for threshold correction of a comparator provided in an embodiment of the present application;
FIG. 3 is a schematic diagram of an apparatus for threshold correction of a comparator according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a signal sampling system according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a signal sampling system according to another embodiment of the present application;
FIG. 6 is a schematic diagram of a signal sampling system according to another embodiment of the present application;
fig. 7 is a schematic structural diagram of a signal sampling system according to another embodiment of the present application.
Detailed Description
The technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only for explaining a part of the embodiments of the present application, but not all embodiments, and are not intended to limit the scope of the present application or the claims. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected/coupled" to another element, it can be directly connected/coupled to the other element or intervening elements may also be present. The term "connected/coupled" as used herein may include electrical and/or mechanical physical connections/couplings. The term "comprising" as used herein refers to the presence of a feature, step or element, but does not exclude the presence or addition of one or more other features, steps or elements. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Unless defined otherwise, 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In addition, in the description of the present application, the terms "first," "second," "third," etc. are used merely for descriptive purposes and distinguishing between similar objects, and not necessarily for describing a sequential or chronological order, nor are they to be construed as indicating or implying relative importance. Furthermore, in the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
Furthermore, the comparator described herein is not limited to use in MVT sampling circuits, and may be applied to any op-amp circuit. Methods, apparatuses, and signal sampling systems for performing threshold correction on a comparator provided in embodiments of the present application are described below with reference to the accompanying drawings.
As shown in fig. 2, an embodiment of the present application provides a method for threshold correction of a comparator, which may include the steps of:
s1, the read comparator compares a reference value received through a first input terminal on the read comparator with an initial sampling threshold value received through a second input terminal on the read comparator to output an initial level.
The comparator may generally comprise two inputs of opposite polarity, e.g. a first input and a second input. Wherein the first input may be used for receiving a reference value and an analog signal to be sampled and the second input may be used for receiving a sampling threshold. The sampling threshold may be an electrical threshold such as a voltage threshold or a current threshold, or may be a threshold of another characteristic. The analog signal may be a pulse signal (e.g., a blinking pulse signal) or may be another type of signal.
The reference value may be fixed data as a reference when the comparator performs threshold correction. For example, the reference value may be a power-on voltage of the system in which the comparator is located, that is, a voltage of the system in which the comparator is located after the system is powered on and before an analog signal to be sampled is sent to the comparator, which may be understood as a reference value of the first input terminal, a voltage provided by an externally provided supply terminal, or a voltage obtained by converting a current on the system. In general, the reference value may be a voltage of 600 mv.
The initial sampling threshold may be pre-estimated data based on historical data or circuit characteristics and may be sized within the range of the element connected to the second input of the comparator. For example, it may be the sum of a reference value and a pre-estimated maximum sampling threshold (e.g., 50 mv) or minimum sampling threshold (e.g., -50 mv), or other values. The minimum and maximum sampling thresholds may be estimated from the range of an element (e.g., a digital-to-analog converter (DAC)) connected to the second input of the comparator.
After the comparator receives the reference value at its first input and the initial sampling threshold at its second input, it compares the reference value with the initial sampling threshold and outputs a corresponding level signal, herein referred to as an initial level, based on the comparison result. For example, the comparator may output a high level signal (e.g., 1) when the reference value is greater than or equal to the initial sampling threshold, and may output a low level signal (e.g., 0) when the reference value is less than the initial sampling threshold.
After the comparator outputs the initial level, the initial level of the comparator output may be read. Specifically, the initial level output from the output terminal of the comparator may be read directly, or the initial level output from the output terminal of the comparator may be read indirectly by a timing unit such as a time-to-digital converter.
S2, adjusting the initial sampling threshold value according to a preset change value to obtain a current sampling threshold value, and providing the current sampling threshold value for the comparator.
After reading the initial level, the current sampling threshold may be obtained by subtracting or adding a preset variation value from the initial sampling threshold, and the obtained current sampling threshold is also within the range of the element connected to the second input of the comparator, that is, the current sampling threshold is greater than or equal to the output minimum value of the element and less than or equal to the output maximum value of the element. For example, when the initial sampling threshold is the sum of the reference value and the minimum sampling threshold, the current sampling threshold may be the sum of the initial sampling threshold and the preset variation value; when the initial sampling threshold is the sum of the reference value and the maximum sampling threshold, the current sampling threshold may be the difference between the initial sampling threshold and the preset variation value. The preset change value may be preset by combining a maximum sampling threshold value and a minimum sampling threshold value which are estimated in advance and according to statistical data or historical experience, or may be preset according to a minimum scale of an element connected with the second input end of the comparator, and the value of the preset change value is generally smaller. For example, it may be 10 times or 20 times the minimum scale of the element.
After the initial sampling threshold is adjusted to the current sampling threshold, the adjusted current sampling threshold may be directly provided to the second input terminal of the comparator, or the current sampling threshold may be provided to the comparator through a DAC or the like.
S3, the current level output by the comparator after comparing the reference value with the current sampling threshold is read.
After the adjusted current sampling threshold is provided to the comparator, the comparator may compare the reference value with the current sampling threshold and output a current level according to the comparison result. For example, the comparator outputs a high level when the reference value is greater than or equal to the current sampling threshold value, and outputs a low level when the reference value is less than the current sampling threshold value.
After the comparator outputs the current level, the current level output by the comparator may be read directly or indirectly through a timing element such as a TDC connected to the output of the comparator.
S4, judging whether the current level is the same as the initial level, and determining a correction threshold of the comparator according to a judging result.
After the current level is read, whether the read current level is the same as the initial level or not can be judged, when the current level is judged to be the same as the initial level, the current level and the current sampling threshold value can be respectively used as the initial level and the initial sampling threshold value, and the steps S2-S3 are repeatedly executed until the current level is judged to be different from the initial level; when it is judged that the current level is different from the initial level, it may be determined that the correction threshold of the comparator is located between the difference value of the initial sampling threshold and the reference value and the difference value of the current sampling threshold and the reference value.
After determining that the correction threshold of the comparator is located between the difference value between the initial sampling threshold and the reference value and the difference value between the current sampling threshold and the reference value, any value between the difference value between the initial sampling threshold and the reference value and the difference value between the current sampling threshold and the reference value can be used as the correction value of the comparator, or the difference value between the current sampling threshold and the reference value or the difference value between the initial sampling threshold and the reference value can be directly used as the correction threshold of the comparator, as shown in formulas (1) and (2); it is also possible to calculate an average or root mean square of the difference between the initial sampling threshold and the reference value and the difference between the current sampling threshold and the reference value, and take the resulting average or root mean square as the correction threshold of the comparator.
Vcali=vcur-vbase=vcali_min+n vcali_step or vcali_max-N vcali_step (1)
Vcali=vori-vbase=vcali_min+ (N-1) vcali_step or vcali_max- (N-1) vcali_step (2)
Wherein Vcali is a correction threshold of the comparator, vcur is a current sampling threshold, vbase is a reference value, vcali_min is a minimum sampling threshold, vcali_max is a maximum sampling threshold, vcali_step is a preset variation value, and N is the number of times of repeatedly executing steps S2 to S3, which is a positive integer.
In another embodiment, in order to improve the accuracy of the obtained correction threshold, after determining that the correction threshold of the comparator is located between the difference value between the initial sampling threshold and the reference value and the difference value between the current sampling threshold and the reference value, the preset variation value may be appropriately reduced, and the initial sampling threshold when the current level is different from the initial level is adjusted and judged by using the reduced preset variation value to obtain the current sampling threshold, and the obtained current sampling threshold is provided to the second input terminal of the comparator; repeating the step of reading the current level (i.e., step S3) and the step of judging whether the current level is the same as the initial level until it is judged that the current level is different from the initial level; when the current level is judged to be different from the initial level, determining the difference value between the initial sampling threshold and the reference value, the difference value between the current sampling threshold and the reference value, or the average value or root mean square of the difference value between the current sampling threshold and the reference value and the difference value between the initial sampling threshold and the reference value at the moment as the correction threshold of the comparator. After the correction threshold is obtained, the sampling threshold to be supplied to the comparator may be set directly according to the correction threshold, so that a more accurate sampling result can be obtained when sampling the analog signal with the system including the comparator.
As can be seen from the above description, the present application achieves automatic threshold correction of a comparator by determining whether an initial level obtained under an initial sampling threshold is the same as a current level obtained under a current sampling threshold obtained by adjusting the initial sampling threshold, that is, determining whether the comparator is inverted, and determining that the comparator is inverted when the initial level is different from the current level, so that it can be determined that a correction threshold of the comparator is located between a difference value between the initial sampling threshold and a reference value and a difference value between the current sampling threshold and the reference value, so that when an analog signal is sampled, an arbitrary value between the difference value between the initial sampling threshold and the reference value and the difference value between the current sampling threshold and the reference value can be directly used as the correction threshold and the sampling threshold can be set according to the correction threshold, without an additional signal generator generating a correction signal, and further, after the system deployment is completed, the comparator can be directly subjected to threshold correction in the same manner, without changing a system structure, that is, a device for supplying the analog signal to be sampled is not required to be disassembled, and a signal generator is connected, which can simplify the operation and save correction time.
The embodiment of the present application further provides an apparatus for performing threshold correction on a comparator, hereinafter collectively referred to as a threshold correction apparatus, as shown in fig. 3, the threshold correction apparatus 300 may include:
a first reading unit 310, which may be configured to read an initial level output by the comparator after comparing a reference value received through a first input terminal thereon with an initial sampling threshold received through a second input terminal thereon;
an adjustment unit 320, which may be configured to adjust the initial sampling threshold according to a preset variation value to obtain a current sampling threshold, and provide the current sampling threshold to the second input terminal of the comparator;
a second reading unit 330, which may be configured to read a current level output by the comparator after comparing the reference value with the current sampling threshold, and may be integrated with the first reading unit 310;
the determining unit 340 may be configured to determine whether the current level is the same as the initial level, and determine a correction threshold of the comparator according to the determination result. Specifically, the determination unit 340 may be configured to: when the initial level is judged to be the same as the current level, the current level and the current sampling threshold are respectively used as the initial level and the initial sampling threshold, and the adjusting unit 320 and the second reading unit 330 are instructed to circularly execute corresponding operations until the current level is judged to be different from the initial level; when it is determined that the current level is different from the initial level, an arbitrary value between the difference between the initial sampling threshold and the reference value and the difference between the current sampling threshold and the reference value may be determined as the correction threshold of the comparator, and preferably, the difference between the initial sampling threshold and the reference value, the difference between the current sampling threshold and the reference value, or the average value or root mean square of the differences between the current sampling threshold and the reference value and the difference between the initial sampling threshold and the reference value may be determined as the correction threshold of the comparator, thereby realizing the threshold correction of the comparator.
For the detailed descriptions of the above units, such as the first reading unit 310, the adjusting unit 320, the second reading unit 330, and the determining unit 340, reference may be made to the descriptions of the corresponding steps in the above method embodiments, which are not repeated herein.
By using the threshold correction device, automatic threshold correction of the comparator can be achieved.
The embodiment of the application also provides a signal sampling system, as shown in fig. 4 and 5. The system may comprise the threshold correction device 300 depicted in fig. 3 and the comparator 200 for threshold correction thereof with the threshold correction device 300.
The system may further comprise a detection device 100, which may be connected to a first input of the comparator 200 for providing an analog signal to be sampled to the comparator 200. The detection device 100 may be any device capable of radiation detection, such as a Magnetic Resonance Imaging (MRI) device, a Computed Tomography (CT) device, a Single Photon Emission Computed Tomography (SPECT) device, a Positron Emission Tomography (PET) device, or a PET-CT device, or other device capable of providing an analog signal to be sampled.
In addition, the system may further include a threshold supply device 400, which may be a digital-to-analog converter (DAC), an adjustable voltage divider circuit, or an adjustable power supply, and both ends of the threshold supply device 400 may be connected to the second input terminal of the comparator 200 and the threshold correction device 300, respectively, to provide the comparator 200 with a plurality of sampling thresholds, which may include an initial sampling threshold, a current sampling threshold, and a preset sampling threshold set according to the obtained correction threshold of the comparator and characteristics of the analog signal, under the control of the threshold correction device 300. At this time, the threshold correction device 300 may be regarded as a controller that may adjust the sampling threshold value provided to the comparator 200 by adjusting the output of the threshold value supply device 400.
In addition, the system may further include a time measuring device 500, which may be a time-to-digital converter (TDC), a time-to-analog converter (TAC), or a timer, an input of which may be connected in parallel with the output of the comparator 200 and the device 300, or an input of which is connected with the output of the comparator 200 and an output of which is connected with the device 300, and may be configured to measure a time when an analog signal to be sampled reaches a preset sampling threshold value according to a level signal output from the comparator 200, so that a sampling point composed of the measured time and the preset sampling threshold value may be obtained.
In another embodiment, as shown in fig. 6, the system may further comprise a data processing device 600, which may be configured to reconstruct the obtained sampling points to obtain a reduced waveform of the analog signal. For a specific process of reconstructing the sampling points, reference may be made to the related description in the prior art, which is not described herein. In addition, the method comprises the following steps. The data processing device 600 may be any computing device having a data processing function, for example, a computer, or may be a part of a computing device, for example, a Central Processing Unit (CPU).
Furthermore, in another embodiment, as shown in fig. 7, the system may further include: a switch 700, which may be provided between the detection device 100 and a first input of the comparator 200; and a supply terminal 800, which may be connected to the switch 700 to provide a reference value to the first input terminal of the comparator 200 in the form of a direct current signal. By switching the switch 700, it is achieved that the reference value is provided in different ways, thereby improving the flexible usability of the system.
The signal sampling system may be any system capable of digitally sampling an analog signal, and preferably may be an MVT sampling circuit.
By using the signal sampling system, the accuracy of the sampling result of the analog signal can be improved, and automatic threshold correction of the comparator can be realized.
The systems, devices, units, etc. described in the above embodiments may be implemented by a semiconductor chip, a computer chip, and/or an entity, or by a product having a certain function. For convenience of description, the above devices are described as being functionally divided into various units, respectively. Of course, the functions of the units may be integrated in the same chip or chips when implementing the embodiments of the present application.
Although the present application provides method operational steps as described in the above embodiments or flowcharts, more or fewer operational steps may be included in the method, either on a routine basis or without inventive labor. In steps where there is logically no necessary causal relationship, the execution order of the steps is not limited to the execution order provided in the embodiments of the present application.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments.
The embodiments described above are intended to facilitate the understanding and use of the present application by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications can be made to these embodiments and that the general principles described herein may be applied to other embodiments without the need for inventive faculty. Accordingly, the present application is not limited to the above-described embodiments, and those skilled in the art, based on the disclosure of the present application, should make improvements and modifications without departing from the scope of the present application.
Claims (19)
1. A method for threshold correction of a comparator, the method comprising the steps of:
reading an initial level output by the comparator after comparing a reference value received through a first input terminal thereon with an initial sampling threshold received through a second input terminal thereon, wherein the first input terminal is further used for receiving an analog signal to be sampled, the comparator outputs a high-level signal as the initial level when the reference value is greater than or equal to the initial sampling threshold, and outputs a low-level signal as the initial level when the reference value is less than the initial sampling threshold;
the initial sampling threshold value is adjusted according to a preset change value to obtain a current sampling threshold value, and the current sampling threshold value is provided to the second input end of the comparator;
reading a current level output by the comparator after comparing the reference value with the current sampling threshold, wherein when the reference value is larger than or equal to the current sampling threshold, the comparator outputs a high-level signal as the current level, and when the reference value is smaller than the current sampling threshold, the comparator outputs a low-level signal as the current level;
determining whether the current level is the same as the initial level, and determining a correction threshold of the comparator according to a determination result, includes: when the initial level is judged to be the same as the current level, respectively taking the current level and the current sampling threshold as the initial level and the initial sampling threshold, and repeating the steps of adjusting the initial sampling threshold and reading the current level until the current level is judged to be different from the initial level; when the current level is judged to be different from the initial level, it is determined that a correction threshold of the comparator is located between a difference value of the initial sampling threshold and the reference value and a difference value of the current sampling threshold and the reference value.
2. The method according to claim 1, wherein after determining that the correction threshold of the comparator is located between the difference between the initial sampling threshold and the reference value and the difference between the current sampling threshold and the reference value, the step of determining the correction threshold of the comparator according to the judgment result further comprises:
and taking the difference value between the initial sampling threshold value and the reference value, the difference value between the current sampling threshold value and the reference value, or the average value or root mean square of the difference value between the current sampling threshold value and the reference value and the difference value between the initial sampling threshold value and the reference value as a correction threshold value of the comparator.
3. The method of claim 1, wherein after determining that the correction threshold of the comparator is between the difference between the initial sampling threshold and the reference value and the difference between the current sampling threshold and the reference value, the method further comprises:
reducing the preset change value, adjusting and judging the initial sampling threshold value when the current level is different from the initial level by using the reduced preset change value to obtain a current sampling threshold value, and providing the obtained current sampling threshold value to the second input end;
repeating the steps of reading the current level and judging whether the current level is the same as the initial level until the current level is different from the initial level;
and when the current level is judged to be different from the initial level, determining the difference value between the initial sampling threshold value and the reference value, the difference value between the current sampling threshold value and the reference value, or the average value or the root mean square of the difference value between the current sampling threshold value and the reference value and the difference value between the initial sampling threshold value and the reference value as the correction threshold value of the comparator.
4. The method according to claim 1, wherein the reference value comprises a power-up voltage of a system in which the comparator is located or a voltage provided by an externally provided supply terminal.
5. The method of claim 1, wherein the initial sampling threshold is a sum of the reference value and a pre-estimated maximum or minimum sampling threshold, and the initial sampling threshold is within a range of an element connected to a second input of the comparator.
6. The method of claim 5, wherein the step of adjusting the initial sampling threshold to obtain the current sampling threshold comprises:
when the initial sampling threshold value is the sum of the reference value and a pre-estimated maximum sampling threshold value, subtracting the preset change value from the initial sampling threshold value to obtain the current sampling threshold value;
and when the initial sampling threshold value is the sum of the reference value and a minimum sampling threshold value estimated in advance, adding the preset change value to the initial sampling threshold value to obtain the current sampling threshold value.
7. The method of claim 1, wherein the predetermined variation value is predetermined based on a minimum scale of an element connected to the second input of the comparator.
8. An apparatus for threshold correction of a comparator, the apparatus operating with the method of any one of claims 1-7, the apparatus comprising:
a first reading unit configured to read an initial level output by the comparator after comparing a reference value received through a first input terminal thereon with an initial sampling threshold value received through a second input terminal thereon, wherein the first input terminal is further used for receiving an analog signal to be sampled;
the adjusting unit is configured to adjust the initial sampling threshold value according to a preset change value to obtain a current sampling threshold value, and provide the current sampling threshold value to the second input end of the comparator;
a second reading unit configured to read a current level output by the comparator after comparing the reference value with the current sampling threshold;
and a determining unit configured to determine whether the current level is the same as the initial level, and determine a correction threshold of the comparator according to a determination result.
9. The apparatus according to claim 8, wherein the determining unit is specifically configured to:
when the initial level is judged to be the same as the current level, respectively taking the current level and the current sampling threshold value as the initial level and the initial sampling threshold value, and indicating the adjusting unit and the second reading unit to circularly execute corresponding operations until the current level is judged to be different from the initial level;
and when the current level is judged to be different from the initial level, determining the difference value between the initial sampling threshold value and the reference value, the difference value between the current sampling threshold value and the reference value, or the average value or the root mean square of the difference value between the current sampling threshold value and the reference value and the difference value between the initial sampling threshold value and the reference value as the correction threshold value of the comparator.
10. A signal sampling system, characterized in that the system comprises a device for threshold correction of the comparator according to claim 8 or 9.
11. The system of claim 10, wherein the system further comprises:
a detection device is connected to the first input of the comparator to provide an analog signal to be sampled to the comparator.
12. The system of claim 11, wherein the detection device comprises an MRI device, a CT device, a SPECT device, a PET device, or a PET-CT device.
13. The system of claim 12, wherein the system further comprises:
a threshold supply means configured to provide a plurality of sampling thresholds to the comparator under control of the means, the plurality of sampling thresholds comprising an initial sampling threshold and a current sampling threshold.
14. The system of claim 13, wherein the threshold supply device comprises a digital-to-analog converter, an adjustable voltage divider circuit, or an adjustable power supply.
15. The system of claim 13, wherein the system further comprises:
and a time measurement device configured to measure a time when the analog signal reaches a preset sampling threshold value based on the level signal output from the comparator, to obtain a sampling point composed of the time and the preset sampling threshold value, the preset sampling threshold value being included in a plurality of the sampling threshold values.
16. The system of claim 15, wherein the time measurement device comprises a time-to-digital converter, a time-to-analog converter, or a timer.
17. The system of claim 15, wherein an input of the time measurement device is connected in parallel with the output of the device and the comparator, or wherein an input of the time measurement device is connected with an output of the comparator and an output of the time measurement device is connected with the device.
18. The system of claim 15, wherein the system further comprises:
and the data processing device is configured to reconstruct the obtained sampling points to obtain a restored waveform of the analog signal.
19. The system of any one of claims 11-18, wherein the system further comprises:
a switch disposed between the detection device and the first input of the comparator;
and a supply terminal connected to the switch to supply a reference value to the first input terminal in the form of a direct current signal.
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| CN202011193208.1A CN112290918B (en) | 2020-10-30 | 2020-10-30 | Method, device and system for threshold correction of comparator |
| PCT/CN2021/118708 WO2022089080A1 (en) | 2020-10-30 | 2021-09-16 | Method and apparatus for performing threshold correction on comparator, and system |
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| CN114448435B (en) * | 2022-01-29 | 2023-01-31 | 中国科学院微电子研究所 | Comparator threshold error calibration method, device, equipment and medium |
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