Dynamic calibration method and system for delay chain

Abstract

The invention discloses a dynamic calibration method and system for a delay chain, and relates to the technical field of time measurement, and the method comprises the following steps: inputting a random pulse with a set time length into a to-be-calibrated delay chain, and obtaining a plurality of jump series outputted by the to-be-calibrated delay chain under different random pulse inputs; judging whether the maximum value in the plurality of jump series is located in a preset confidence interval or not, and obtaining the maximum number of current interpolation delay units of the delay chain to be calibrated according to a judgment result; the actual delay duration of the delay units in the delay chain to be calibrated is obtained through the maximum number of the current interpolation delay units and the clock signal, and the delay chain to be calibrated is calibrated through the actual delay duration. According to the invention, the resolution of the time interval is dynamically monitored, the actual value of the time resolution instead of the preset value is used in the calculation of the time interval, the deviation of the measured value of the time interval is reduced, the delay change caused by the change of the external environment is compensated, and the precision of the time measurement result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of time measurement, and in particular to a dynamic calibration method and system for a delay chain. Background Art

[0002] High-precision time interval measurement is widely used in the field of high-energy physics, and the corresponding high-precision time measurement solutions are widely used in fluorescence imaging, space exploration, astronomical observation, positron emission tomography, laser ranging, autonomous driving, aerospace, radar positioning, three-dimensional imaging, fluid flow measurement, electronic instruments and ground robots. The resolution of high-precision time interval measurement is usually within a hundred picoseconds. In recent years, with the increase in demand, time interval measurement needs to achieve a time resolution of more than ten picoseconds.

[0003] The time-to-digital converter based on the interpolation delay chain method is a high-precision time interval measurement solution. Accuracy and nonlinear effects are critical indicators of the time-to-digital converter. The interpolation delay chain method divides a clock cycle into multiple delay units for interpolation, and obtains high-precision time intervals through the number and quantity of delay units.

[0004] However, in the actual application of the existing delay chain, the delay unit will be affected by the voltage and external temperature changes, resulting in dynamic changes in the length of the delay chain. When the delay time of the delay unit becomes shorter, the delay chain becomes longer, resulting in an increase in the minimum resolution of time measurement; when the delay time of the delay unit becomes longer, the delay chain becomes shorter, resulting in a decrease in the minimum resolution of time measurement. In the above process, the deviation between the ideal value and the actual value of the time resolution of the delay chain will continue to change, resulting in low accuracy of the final time interval measurement result. Summary of the invention

[0005] Based on the defects of the above-mentioned prior art, the present invention provides a dynamic calibration method and system for a delay chain, which solves the problem that the deviation between the ideal value and the actual value of the time resolution of the existing delay chain changes continuously, resulting in low accuracy of the final time measurement result.

[0006] The present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for dynamic calibration of a delay chain, comprising the following steps:

[0008] Inputting a random pulse of a set duration into the delay chain to be calibrated, and obtaining a plurality of jump levels of the output of the delay chain to be calibrated under different random pulse inputs; wherein the random pulse has no correlation with the clock signal of the delay chain to be calibrated;

[0009] It is judged whether the maximum value among the multiple jump levels is within a preset confidence interval, and the maximum number of the current interpolation delay units of the delay chain to be calibrated is obtained according to the judgment result;

[0010] The actual delay length of the delay unit in the delay chain to be calibrated is obtained by the maximum number of the current interpolated delay units and the clock signal, and the delay chain to be calibrated is calibrated by the actual delay length.

[0011] Preferably, the confidence interval is a variation interval of a maximum jump value obtained by measuring a random pulse within an allowable operating range of voltage and temperature.

[0012] Preferably, judging whether the maximum value among the plurality of jump levels is within a preset confidence interval and obtaining the maximum number of current interpolation delay units of the delay chain to be calibrated according to the judgment result comprises the following steps:

[0013] If the maximum value among the multiple jump levels is within the confidence interval, the number of interpolation delay units corresponding to the maximum value is used as the maximum number of current interpolation delay units;

[0014] If the maximum value among the multiple jump series is not within the confidence interval, a random pulse of a set duration is re-input into the delay chain to be calibrated, and multiple jump series output by the delay chain to be calibrated under different random pulse inputs are obtained. The maximum value among the multiple jump series is compared with the confidence interval until the maximum value among the multiple jump series is within the confidence interval.

[0015] Preferably, the actual delay length of the delay unit in the delay chain to be calibrated is obtained by using the maximum number of currently interpolated delay units and the clock signal, as shown below:

[0016]

[0017] Where N max is the maximum number of current interpolation delay units, T clk is the clock signal, t′ d The actual delay duration.

[0018] Preferably, it also includes:

[0019] Input the time interval to be measured into the calibrated delay chain for measurement to obtain the corresponding jump level;

[0020] The corresponding jump level is multiplied by the actual delay time length of the delay unit to obtain the measurement result of the time interval to be measured.

[0021] Preferably, the corresponding jump level is multiplied by the actual delay time length of the delay unit to obtain the measurement result of the time interval to be measured, which is specifically as follows:

[0022] t=t′ d *N 0 ;

[0023] Where t is the measurement result of the time interval to be measured, N 0 is the number of transition levels measured in the calibrated delay chain during the time interval to be measured.

[0024] In a second aspect, the present invention provides a dynamic calibration system for a delay chain, comprising:

[0025] An input module, used for inputting a random pulse of a set duration into the delay chain to be calibrated, and obtaining a plurality of jump levels outputted by the delay chain to be calibrated under different random pulse inputs; wherein the random pulse has no correlation with the clock signal of the delay chain to be calibrated;

[0026] A judgment module, used to judge whether the maximum value among the multiple jump levels is within a preset confidence interval, and obtain the maximum number of current interpolation delay units of the delay chain to be calibrated according to the judgment result;

[0027] The calibration module is used to obtain the actual delay length of the delay unit in the delay chain to be calibrated through the maximum number of the current interpolated delay units and the clock signal, and calibrate the delay chain to be calibrated through the actual delay length.

[0028] Compared with the prior art, at least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0029] The present invention proposes a dynamic calibration method for a delay chain. First, a random pulse of a set duration is input to the delay chain to be calibrated. The random pulse input by the present invention has no correlation with the clock signal of the delay chain to be calibrated, ensuring that the probability density distribution within a clock cycle is uniformly distributed, and the edge of the pulse signal can be quickly brought as close to the edge of the clock signal as possible. Then, multiple jump levels output by the delay chain to be calibrated under different random pulse inputs are obtained, and whether the maximum value among the multiple jump levels is located in a preset confidence interval is judged. According to the judgment result, the maximum number of current interpolated delay units of the delay chain to be calibrated is obtained, ensuring that the current resolution is closest to the actual value. Finally, the actual delay duration of the delay unit in the delay chain to be calibrated is obtained by the maximum number of current interpolated delay units and the clock signal, and the delay chain to be calibrated is calibrated by the actual delay duration. The present invention dynamically monitors the resolution of the time interval, so that the actual value of the time resolution rather than the preset value is used in the calculation of the time interval, reduces the deviation of the time interval measurement value, compensates for the delay change caused by the change of the external environment, and improves the accuracy of the time measurement result. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a flow chart of a dynamic calibration method of a delay chain of the present invention;

[0032] Figure 2 It is a structural diagram of the delay chain;

[0033] Figure 3 It is a flowchart of a dynamic calibration system of a delay chain of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The specific structure of the existing delay chain is as follows Figure 2 As shown. The interpolation delay chain method expresses the time interval ΔT between the start signal and the stop signal to be measured in the form of "coarse count" + "fine count". Coarse count means that time is measured in clock cycles. When the time interval is less than one cycle, coarse count cannot be quantified, and the measurement result of the time interval less than one clock cycle will be expressed by fine count. By combining coarse and fine quantization, high-precision time measurement can be achieved.

[0036] The interpolation delay chain divides a clock cycle into multiple delay units for interpolation, where the first fine counting result t 1 is the interval between the start signal and the sampling clock edge, and the second fine counting result t 2 is the interval between the stop signal and the sampling clock edge, and the coarse count result is T. d is the delay of the first-level interpolation delay unit, T clk is the clock cycle, and N is the number of clock cycles. The first detailed counting result t 1 and the second detailed counting result t 2 It is represented by the number of interpolated delay units in the corresponding interval. 1 , N 1 t 1 Interpolation T dFor the second detailed counting result t 2 , N 2 t 2 Interpolation T d The time interval calculation formula is shown in formula (1):

[0037] ΔT=t 1 +Tt 2 =(N 1 -N 2 )*T d +N*T clk (1).

[0038] The trigger samples the output of each level of the delay chain, and then decodes the sampling results to find the jump level. The total delay time accumulated to this level is the fine quantization result, which is t 1 and t 2 .

[0039] Usually the propagation delay length of the device's inherent delay unit is T d If it tends to be constant, the length of the delay chain composed of the delay units is fixed, and the total number of delay units in the delay chain can be obtained by formula (2).

[0040]

[0041] Where N 3 Represents the total number of delay units.

[0042] In an ideal operating environment, the maximum number of delay units that can be interpolated in the delay chain is fixed. When the operating environment changes, the delay time of the delay unit changes, and the length of the delay chain changes accordingly, resulting in a change in the maximum number of delay units that can be interpolated in the delay chain.

[0043] Based on the above problems, refer to Figure 1 The present invention proposes a dynamic calibration method for a delay chain, which can dynamically monitor the maximum number of delay units that can be interpolated in the delay chain, and can obtain the maximum number of delay units N. max With clock period T clk The delay time T of the single-stage delay unit can be deduced by formula (2). d , making it closest to the actual value. During the application process, the delay time T of the current single-stage delay unit is refreshed by continuous measurement through calibration. d , get the current actual time resolution, compensate for the delay changes caused by changes in the external environment, and make the time measurement more accurate. It includes the following steps:

[0044] S1: Input a random pulse of a set duration to the delay chain to be calibrated, and obtain multiple jump levels of the output of the delay chain to be calibrated under different random pulse inputs.

[0045] The portion of the time interval ΔT that is less than one clock cycle (such as t 1 , t 2 ) will propagate in the delay chain. When the signal has propagated in the delay chain for a period of time equal to t 1 or 2 When they are equal, the signal can be jumped to the number of delay units propagated at this time.

[0046] When the edge of the signal to be tested is closer to the edge of the clock signal, the jump level of the delay unit obtained at this time is closer to the maximum number of interpolated delay units N. max Therefore, the calibration of the present invention uses a random pulse input into the delay chain to be calibrated for propagation. The random pulse needs to be consistent with T clk The two signals are non-correlated. The stronger the non-correlation is, the higher the calibration efficiency is when the number of pulses is limited. Because the probability density distribution of the random pulse signal in one clock cycle is uniform, the signal edge can be quickly brought as close to the clock edge as possible, and the maximum number of the current interpolation delay units can be found.

[0047] S2: judging whether the maximum value among the plurality of jump levels is within a preset confidence interval, and obtaining the maximum number of current interpolation delay units of the delay chain to be calibrated according to the judgment result.

[0048] During calibration, a random pulse of a certain length is given, and the number of jump levels measured for each pulse is recorded to find the maximum value. The maximum value is compared with the preset confidence interval to obtain the maximum number of the current interpolation delay unit. If the maximum value does not meet the confidence interval, the random pulse is input again to find the maximum jump value until the confidence interval is met. The confidence interval is the variation interval of the maximum jump value obtained by measuring the boundary value of the random pulse at the allowable working range of voltage and temperature. When the temperature is fixed, high voltage corresponds to the upper limit of the confidence interval, and low voltage corresponds to the lower limit; when the voltage is fixed, high temperature corresponds to the lower limit of the confidence interval, and low temperature corresponds to the upper limit. High temperature and low temperature correspond to the maximum and minimum values ​​of the boundary value of the working range. The confidence interval ensures the correctness of the calibration result.

[0049] S3: Obtaining the actual delay length of the delay unit in the delay chain to be calibrated through the maximum number of the current interpolated delay units and the clock signal.

[0050] Based on formula (2), the actual delay length of the delay unit in the delay chain to be calibrated is obtained, which is as follows:

[0051]

[0052] Where N max is the maximum number of current interpolation delay units, T clk is the clock signal, t′d The actual delay duration.

[0053] The maximum number of the current interpolation delay units is taken as N max Substituting into formula (3), the actual value of the current delay time can be obtained. The time interval of the delay chain to be calibrated is calibrated by the actual delay time of the delay unit, as shown below:

[0054] t=t′ d *N 0 (4);

[0055] Where t is the measurement result of the time interval to be measured, N 0 is the number of transition levels measured in the calibrated delay chain during the time interval to be measured.

[0056] The corresponding t 1 and t 2 The calculation of is shown in formula (5) and formula (6).

[0057]

[0058] The resolution uses default values ​​before calibration, which are measured using typical values ​​of voltage and temperature.

[0059] Through this calibration method, the resolution of the time interval is dynamically monitored, so that the actual value of the time resolution rather than the preset value is used in the calculation of the time interval, reducing the deviation of the time interval measurement value. Since the device delay change caused by the environment is not transient, the signal can be provided only when calibration is required to reduce power consumption.

[0060] Based on the same concept, Figure 3 The present invention also provides a dynamic calibration system for a delay chain, including an input module, a judgment module and a calibration module.

[0061] The input module is used to input random pulses of set duration to the delay chain to be calibrated, and obtain multiple jump levels of the output of the delay chain to be calibrated under different random pulse inputs; wherein the random pulses are non-correlated with the clock signal of the delay chain to be calibrated.

[0062] The judging module is used to judge whether the maximum value among the multiple jump levels is located in a preset confidence interval, and obtain the maximum number of current interpolation delay units of the delay chain to be calibrated according to the judging result.

[0063] The calibration module is used to obtain the actual delay length of the delay unit in the delay chain to be calibrated through the maximum number of the current interpolated delay units and the clock signal, and calibrate the delay chain to be calibrated through the actual delay length.

[0064] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0065] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A dynamic calibration method for a delay chain, characterized in that: The following steps are involved: Inputting a random pulse of a set duration into the delay chain to be calibrated, and obtaining a plurality of jump levels of the output of the delay chain to be calibrated under different random pulse inputs; wherein the random pulse has no correlation with the clock signal of the delay chain to be calibrated; It is judged whether the maximum value among the multiple jump levels is within a preset confidence interval, and the maximum number of the current interpolation delay units of the delay chain to be calibrated is obtained according to the judgment result; The actual delay length of the delay unit in the delay chain to be calibrated is obtained by the maximum number of the current interpolated delay units and the clock signal, and the delay chain to be calibrated is calibrated by the actual delay length.

2. A method for dynamic calibration of a delay chain as claimed in claim 1, characterized in that: The confidence interval is a variation interval of the maximum jump value obtained by measuring the random pulse within the allowable working range of voltage and temperature.

3. A method for dynamic calibration of a delay chain as claimed in claim 2, characterized in that: The step of judging whether the maximum value among the plurality of jump levels is within a preset confidence interval and obtaining the maximum number of current interpolation delay units of the delay chain to be calibrated according to the judgment result comprises the following steps: If the maximum value among the multiple jump levels is within the confidence interval, the number of interpolation delay units corresponding to the maximum value is used as the maximum number of current interpolation delay units; If the maximum value among the multiple jump series is not within the confidence interval, a random pulse of a set duration is re-input into the delay chain to be calibrated, and multiple jump series output by the delay chain to be calibrated under different random pulse inputs are obtained. The maximum value among the multiple jump series is compared with the confidence interval until the maximum value among the multiple jump series is within the confidence interval.

4. A method for dynamic calibration of a delay chain as claimed in claim 1, characterized in that: The actual delay length of the delay unit in the delay chain to be calibrated is obtained by the maximum number of the current interpolated delay units and the clock signal, as shown below: Where N max is the maximum number of current interpolation delay units, T clk is the clock signal, t′ d The actual delay duration.

5. A method for dynamic calibration of a delay chain as claimed in claim 4, characterized in that: Also includes: Input the time interval to be measured into the calibrated delay chain for measurement to obtain the corresponding jump level; The corresponding jump level is multiplied by the actual delay time length of the delay unit to obtain the measurement result of the time interval to be measured.

6. A method for dynamic calibration of a delay chain as claimed in claim 5, characterized in that: The corresponding jump level is multiplied by the actual delay time of the delay unit to obtain the measurement result of the time interval to be measured, which is specifically shown as follows: t=t′ d *N0; Wherein, t is the measurement result of the time interval to be measured, and N0 is the number of jump levels obtained by measuring the time interval to be measured in the calibration delay chain.

7. A dynamic calibration system for a delay chain, characterized in that: include: An input module, used for inputting a random pulse of a set duration into the delay chain to be calibrated, and obtaining a plurality of jump levels outputted by the delay chain to be calibrated under different random pulse inputs; wherein the random pulse has no correlation with the clock signal of the delay chain to be calibrated; A judgment module, used to judge whether the maximum value among the multiple jump levels is within a preset confidence interval, and obtain the maximum number of current interpolation delay units of the delay chain to be calibrated according to the judgment result; The calibration module is used to obtain the actual delay length of the delay unit in the delay chain to be calibrated through the maximum number of the current interpolated delay units and the clock signal, and calibrate the delay chain to be calibrated through the actual delay length.

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