Extremely low temperature measurement method and system based on pulse phase interleaving and storage medium

Abstract

The invention discloses an extremely low temperature measurement method and system based on pulse phase interleaving and a storage medium, and relates to the technical field of temperature measurement, and the extremely low temperature measurement method comprises the following steps: S1, carrying out the calibration and mismatch correction of two sampling channels of a measurement system, obtaining a zero bias voltage, a system gain difference and a sampling time sequence offset, the measured voltage is compensated according to the zero bias voltage and the system gain difference; s2, parameters of a measurement system are set; s3, pulse phase configuration is carried out, so that a pulse constant current source module of the measurement system outputs two paths of pulses with the same amplitude and staggered phases; s4, synchronizing a sampling time sequence, synchronizing a sampling point of each sampling channel to a stable platform area of the pulse, and avoiding an edge area of the pulse; and S5, carrying out unbiased weighted average on the sampling values of the two sampling channels, and obtaining the measured temperature according to the resistance-temperature curve. According to the invention, errors caused by thermal noise in the measurement process are reduced, and the measurement precision is improved.

Description

Technical Field

[0001] This invention relates to the field of temperature measurement technology, and in particular to a method, system and storage medium for ultra-low temperature measurement based on pulse phase interleaving. Background Technology

[0002] In the cryogenic regions below 120 K, and especially below 24.5561 K, highly accurate thermodynamic temperature measurements are crucial for the development of modern science and technology. Their applications include, but are not limited to, particle physics experiments (such as the Large Hadron Collider (LHC), deep space exploration (such as the European Space Agency's Planck project), new energy development, and the currently popular field of quantum computing. For example, the LHC experiment requires the deployment of over 6000 temperature sensors with an accuracy controlled within 5 mK; the Planck detector operates at 0.1 K, with a tolerance of 1 mK for temperature fluctuations. For example, the LHC experiment requires the deployment of more than 6,000 temperature sensors with an accuracy controlled within 5 mK; the Planck detector operates at a temperature of 0.1 K and has a tolerance of 1 mK for temperature fluctuations.

[0003] In quantum computing, the most commonly used Josephson junction structure in superconducting qubit circuits is currently Al / AlOX / Al. Aluminum's superconducting transition temperature is approximately 1.39 K, therefore, the normal operation of a Josephson junction requires an ambient temperature maintained below 1 K. Furthermore, due to the extreme fragility of quantum states, quantum chips need to operate within the mK temperature range; even minute temperature fluctuations can lead to the loss of quantum information. Dilution refrigerators provide the necessary extremely low-temperature environment for the normal operation of quantum computers and are irreplaceable key equipment in quantum computing research. Meanwhile, extremely low-temperature measurement systems provide the conditions for measuring this environment.

[0004] Lake Shore, a US company dedicated to cryogenic measurement, has achieved significant results in the field, with its products and technologies widely used in scientific research, industrial applications, and high-tech sectors. Its Cernox temperature sensors, suitable for temperatures from 100mK to 325K, feature low magnetic field error, excellent resistance to ionizing radiation, fast response time, and good sensitivity across the entire temperature range. Lake Shore's RX-202A ruthenium oxide sensor is a thick-film resistance temperature sensor with a temperature measurement range of 0.05K–40K, suitable for use in magnetic field environments. The LakeShore 372 AC resistance bridge and temperature controller provide optimal temperature measurement and control capabilities for dilution refrigerators, employing four-wire AC sine wave measurement technology to measure temperatures below 100mK. It features multiple PID controllable outputs and 16 measurement channels, providing heater power up to 10W. The TC290 temperature controller, developed by Nanjing Dexin Yijia Electronic Technology Co., Ltd., boasts high resolution, high accuracy, and high stability. It supports diode, platinum resistance, negative temperature coefficient resistance sensors, and thermocouple temperature sensors. By selecting different temperature sensors, accurate temperature measurement from 300mK to 1500K can be achieved. The TC202 temperature controller can achieve precise measurement and temperature control within the temperature range of 1.4K to 450K, with a measurement resolution of 0.01K.

[0005] Currently, China lacks available products and equipment for cryogenic measurement, and research in this area is insufficient. Faced with foreign technological blockades and equipment embargoes, the field of cryogenic measurement is facing severe challenges. Summary of the Invention

[0006] Based on the technical problems existing in the background technology, the present invention proposes an ultra-low temperature measurement method, system and storage medium based on pulse phase interleaving, which reduces the error caused by thermal noise during the measurement process and improves the measurement accuracy.

[0007] The present invention proposes an ultra-low temperature measurement method based on pulse phase interleaving, the method steps of which are as follows:

[0008] S1: The two sampling channels of the measurement system are calibrated and mismatched to obtain the zero-point bias voltage, system gain difference and sampling timing offset, and the measured voltage is compensated based on the zero-point bias voltage and system gain difference.

[0009] S2: Set the parameters of the measurement system;

[0010] S3: Configure the pulse phase so that the pulse constant current source module of the measurement system outputs two pulses with the same amplitude but staggered phase;

[0011] S4: Synchronous sampling timing, the sampling points of each sampling channel are synchronized to the stable plateau region of its pulse, avoiding the edge region of the pulse;

[0012] S5: Perform an unbiased weighted average of the sampled values ​​from the two sampling channels, and obtain the measured temperature based on the resistance-temperature curve.

[0013] Preferably, the method for measuring the zero-point bias voltage in S1 is as follows: turn off the pulse constant current source, short-circuit the two ends of the resistance temperature sensor, collect N sets of data on the two sampling channels respectively, and take the average voltage value to obtain the zero-point bias voltage of the two sampling channels. A and O B ;

[0014] The method for measuring system gain difference is as follows: input a standard voltage V to the resistance temperature sensor. A and V B And record the voltages acquired by the two sampling channels. and Then, the actual gain factor g of the two sampling channels is obtained through linear regression. A and g B .

[0015] Preferably, the method for compensating the measured voltage is as follows:

[0016]

[0017] In the formula, V is the measured voltage; O is the zero-point bias of the sampling channel; g is the actual gain factor of the sampling channel; and V' is the compensated voltage.

[0018] Preferably, the sampling timing offset detection method is as follows: input a standard square wave signal, record the sampling data of two sampling channels, compare the relative positions of the rising / falling edges, find the point in the sampling data of the first sampling channel where the rising edge crosses a certain fixed threshold, and find the corresponding point in the sampling data of the second sampling channel, calculate the difference between the sample points where the edge appears, and obtain the sampling timing offset.

[0019] Preferably, the parameters set in S2 include pulse current amplitude, pulse width, duty cycle, filter cutoff frequency, ADC sampling rate, and cooling interval.

[0020] Preferably, the two pulses output in S3 are:

[0021]

[0022]

[0023] In the formula, I A For the pulse of the first sampling channel; IB For the pulse of the second sampling channel; I p is the amplitude of the pulse current; rect() is the rectangular pulse function; t is the time variable; T p is the basic pulse period; D is the duty cycle.

[0024] Preferably, the sampling centers of the two sampling channels are as follows:

[0025]

[0026]

[0027] In the formula, t A The sampling center for the first sampling channel; t B The sampling center of the second sampling channel; n is the pulse sequence number; T p The basic pulse period; Group delay; t settle This is the plateau settling time after the current source at the front end experiences a step jump.

[0028] Preferably, the resistance value is obtained by unbiased weighted averaging. for:

[0029]

[0030]

[0031]

[0032] In the formula, V' is the weighting coefficient for the first sampling channel; A The voltage after compensation for the first sampling channel; V' is the weighting coefficient for the second sampling channel; B The voltage after compensation for the second sampling channel; This refers to the amplitude of the pulse current. This represents the noise variance of the second sampling channel; This represents the noise variance of the second sampling channel.

[0033] This invention proposes a cryogenic measurement system based on pulse phase interleaving, comprising:

[0034] The calibration module is used to calibrate and correct the mismatch between the two sampling channels of the measurement system, obtain the zero-point bias voltage, system gain difference and sampling timing offset, and compensate the measured voltage based on the zero-point bias voltage and system gain difference.

[0035] The pulse constant current source module is used to set the parameters of the measurement system and configure the pulse phase, so that the pulse constant current source module of the measurement system outputs two pulses with the same amplitude but staggered phase.

[0036] The ADC sampling module is used to synchronize the sampling timing. The sampling points of each sampling channel are synchronized to the stable plateau region of its pulse, avoiding the edge region of the pulse.

[0037] The data processing module is used to perform an unbiased weighted average of the sampled values ​​from the two sampling channels and obtain the measured temperature based on the resistance-temperature curve.

[0038] The present invention proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the ultra-low temperature measurement method based on pulse phase interleaving as described above.

[0039] Beneficial technical effects of the present invention:

[0040] This invention eliminates systematic errors between channels through zero-point bias correction and gain factor compensation, ensuring that the measured voltage is closer to the true value. It employs pulse phase interleaving technology to alternately load the sensor with two constant current pulses for complementary sampling. By sampling in the steady-state plateau region, it avoids the unstable parts of the current rising / falling edges, reducing transient noise interference. It uses unbiased weighted averaging to achieve optimal fusion of the two measurement data, suppressing the influence of single-channel noise. Under extremely low temperature conditions, it can achieve higher resolution and stability than traditional DC or single-pulse measurements. Attached Figure Description

[0041] Figure 1 This is a flowchart of the cryogenic measurement method based on pulse phase interleaving proposed in this invention;

[0042] Figure 2 This is a schematic diagram of the pulse phase interleaving proposed in this invention. Detailed Implementation

[0043] The present invention will be further explained below with reference to specific embodiments.

[0044] Example 1

[0045] The present invention proposes an ultra-low temperature measurement method based on pulse phase interleaving, the method steps of which are as follows:

[0046] S1: The two sampling channels of the measurement system are calibrated and mismatched to obtain the zero-point bias voltage, system gain difference and sampling timing offset, and the measured voltage is compensated based on the zero-point bias voltage and system gain difference.

[0047] The method for measuring the zero-point bias voltage is as follows: The pulse constant current source is turned off (output current is 0), and the two ends of the resistance temperature sensor are short-circuited (ensuring the theoretical voltage across the sensor is 0). N sets of data are collected from both sampling channels, and the average voltage value is taken to obtain the zero-point bias voltage O of the two sampling channels. A and O B .

[0048] The method for measuring system gain difference is as follows: input a standard voltage V to the resistance temperature sensor. A and V B And record the voltages acquired by the two sampling channels. and Then, the actual gain factor g of the two sampling channels is obtained through linear regression. A and g B .

[0049] The linear relationship is as follows:

[0050]

[0051]

[0052] The method for compensating the measured voltage is as follows:

[0053]

[0054] In the formula, V is the measured voltage; O is the zero-point bias of the sampling channel; g is the actual gain factor of the sampling channel; and V' is the compensated voltage.

[0055] Due to asynchronous ADC sampling triggering, there may be a relative time offset between the sampling of the two channels, which can cause significant errors at signal edges. Therefore, the sampling timing offset is calibrated: Input a standard square wave signal, record the sampling data of the two sampling channels, compare the relative positions of the rising / falling edges, and find the point in the sampling data of the first sampling channel where the rising edge crosses a certain fixed threshold (such as 50% amplitude), denoted as n. A And in the sampling data of the second sampling channel, find the corresponding point, denoted as n. B Calculate the difference between sample points appearing at the edge to obtain the sampling time offset t. skew .

[0056]

[0057] In the formula, T s Given the sampling period of the ADC, after calculating the time offset, the corresponding time offset can be adjusted in the MCU to align the sampling of different ADC channels.

[0058] S2: Set the parameters of the measurement system. Specific parameters include pulse current amplitude, pulse width, duty cycle, filter cutoff frequency, ADC sampling rate, and cooling interval (to avoid heat buildup). These parameters determine the measurement sensitivity, noise level, and power consumption. It is essential to avoid sensor heat buildup while ensuring low noise levels.

[0059] S3: Configure the pulse phase so that the pulse constant current source module of the measurement system outputs two pulses with the same amplitude but staggered phases, ensuring that the interleaved pulses do not overlap, while allowing sufficient cooling time.

[0060] The two output pulses are as follows:

[0061]

[0062]

[0063] In the formula, I A For the pulse of the first sampling channel; I B For the pulse of the second sampling channel; I p is the amplitude of the pulse current; rect() is the rectangular pulse function; t is the time variable; T p The basic pulse period is denoted by D, which is the duty cycle. D ≤ 0.4 to ensure that the two interleaved pulses do not overlap, while allowing cooling time to avoid self-heating accumulation in the sensor.

[0064] S4: Synchronous sampling timing. The sampling points of each sampling channel are synchronized to the stable plateau region of its pulse, avoiding the edge region of the pulse. Avoiding the edge region of the pulse avoids errors caused by excessive instability.

[0065] The sampling centers of the two sampling channels of the steady-state sampling window are as follows:

[0066]

[0067]

[0068] In the formula, t A The sampling center for the first sampling channel; t B The sampling center of the second sampling channel; n is the pulse sequence number; T p The basic pulse period; Group delay; t settle This is the plateau settling time after the current source at the front end experiences a step jump.

[0069] The sampling window width w of the steady-state sampling window s satisfy:

[0070]

[0071] In the formula, t acq for; is the pulse width; margin is a safety margin to avoid edge effects or circuit noise.

[0072] The lower limit of the sampling window width ensures that the ADC sampling has at least sufficient hold time, while the upper limit is set to avoid sampling in unstable edge regions. Setting the sampling window width ensures that the two sampling paths are aligned on the same time base, reducing timing jitter.

[0073] S5: Perform an unbiased weighted average of the sampled values ​​from the two sampling channels, and obtain the measured temperature based on the resistance-temperature curve.

[0074] The resistance value is obtained by unbiased weighted averaging. for:

[0075]

[0076]

[0077]

[0078] In the formula, V' is the weighting coefficient for the first sampling channel; A The voltage after compensation for the first sampling channel; V' is the weighting coefficient for the second sampling channel; B The voltage after compensation for the second sampling channel; This refers to the amplitude of the pulse current. This represents the noise variance of the second sampling channel; This represents the noise variance of the second sampling channel.

[0079] The error in temperature measurement between the method of this embodiment and existing methods was detected, and the results are as follows:

[0080] Method A (existing DC method): A small current (e.g., 100nA) is applied using a conventional DC constant current source, and the DC voltage across the sensor is directly measured using a high-precision digital multimeter. This method is susceptible to 1 / f noise and thermoelectric potential. At a temperature of around 10K, the error is approximately 20mK.

[0081] Method B (existing single-pulse method): This method uses a single-channel pulse constant current source, with pulse parameters (amplitude, width, period) consistent with the single-channel pulse parameters in the method of this invention. The sampling point is located at the center of the pulse plateau region. This method avoids some of the 1 / f noise of the DC method, but it cannot suppress noise related to the pulse frequency, and since it only uses single-channel sampling, it cannot be further denoised through signal processing. At a temperature of around 10K, the error is approximately 10mK.

[0082] Method C (Pulse Phase Interleaving Method of the Invention): Strictly follow steps S1 to S5 of the specification of this invention. First, perform dual-channel calibration and mismatch correction. Then, apply dual-path pulse currents with 180-degree phase interleaving, and perform synchronous sampling at the center of their respective stable plateau regions. Finally, perform unbiased weighted averaging based on noise variance. At a temperature of approximately 10K, the error is approximately 6.2mK.

[0083] Example 2

[0084] This invention proposes a cryogenic measurement system based on pulse phase interleaving, comprising:

[0085] The calibration module is used to calibrate and correct the mismatch between the two sampling channels of the measurement system, obtain the zero-point bias voltage, system gain difference and sampling timing offset, and compensate the measured voltage based on the zero-point bias voltage and system gain difference.

[0086] The pulse constant current source module is used to set the parameters of the measurement system and configure the pulse phase, so that the pulse constant current source module of the measurement system outputs two pulses with the same amplitude but staggered phase.

[0087] The ADC sampling module is used to synchronize the sampling timing. The sampling points of each sampling channel are synchronized to the stable plateau region of its pulse, avoiding the edge region of the pulse.

[0088] The data processing module is used to perform an unbiased weighted average of the sampled values ​​from the two sampling channels and obtain the measured temperature based on the resistance-temperature curve.

[0089] Example 3

[0090] The present invention proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the cryogenic measurement method based on pulse phase interleaving as described in Example 1.

[0091] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the appended claims and their equivalents, all of which should be included within the protection scope of this application.

Claims

1. A method for measuring cryogenic temperatures based on pulse phase interleaving, characterized in that, The steps are as follows: S1: The two sampling channels of the measurement system are calibrated and mismatched to obtain the zero-point bias voltage, system gain difference and sampling timing offset, and the measured voltage is compensated based on the zero-point bias voltage and system gain difference. S2: Set the parameters of the measurement system; S3: Configure the pulse phase so that the pulse constant current source module of the measurement system outputs two pulses with the same amplitude but staggered phase; S4: Synchronous sampling timing, the sampling points of each sampling channel are synchronized to the stable plateau region of its pulse, avoiding the edge region of the pulse; S5: Perform an unbiased weighted average of the sampled values ​​from the two sampling channels, and obtain the measured temperature based on the resistance-temperature curve.

2. The cryogenic measurement method based on pulse phase interleaving according to claim 1, characterized in that, The method for measuring the zero-point bias voltage in S1 is as follows: Turn off the pulse constant current source, short-circuit the two ends of the resistance temperature sensor, and collect N sets of data from both sampling channels. Take the average voltage value to obtain the zero-point bias voltage O of the two sampling channels. A and O B ; The method for measuring system gain difference is as follows: input a standard voltage V to the resistance temperature sensor. A and V B And record the voltages acquired by the two sampling channels. and Then, the actual gain factor g of the two sampling channels is obtained through linear regression. A and g B .

3. The cryogenic measurement method based on pulse phase interleaving according to claim 2, characterized in that, The method for compensating the measured voltage is as follows: In the formula, V is the measured voltage; O is the zero-point bias of the sampling channel; g is the actual gain factor of the sampling channel; and V' is the compensated voltage.

4. The cryogenic measurement method based on pulse phase interleaving according to claim 1, characterized in that, The sampling timing offset detection method is as follows: Input a standard square wave signal, record the sampling data of two sampling channels, compare the relative positions of the rising / falling edges, find the point in the sampling data of the first sampling channel where the rising edge crosses a certain fixed threshold, and find the corresponding point in the sampling data of the second sampling channel. Calculate the difference between the sample points where the edge appears to obtain the sampling timing offset.

5. The cryogenic measurement method based on pulse phase interleaving according to claim 1, characterized in that, The parameters set in S2 include pulse current amplitude, pulse width, duty cycle, filter cutoff frequency, ADC sampling rate, and cooling interval.

6. The cryogenic measurement method based on pulse phase interleaving according to claim 1, characterized in that, The two pulses output in S3 are: In the formula, I A The pulse for the first sampling channel; I B For the pulse of the second sampling channel; I p The amplitude of the pulse current is denoted as rect(); rect() is the rectangular pulse function. t is a time variable; T p is the basic pulse period; D is the duty cycle.

7. The cryogenic measurement method based on pulse phase interleaving according to claim 1, characterized in that, The sampling centers of the two sampling channels are as follows: In the formula, t A This serves as the sampling center for the first sampling channel; t B The sampling center of the second sampling channel; n is the pulse sequence number; T p The basic pulse period; Group delay; t settle This is the plateau settling time after the current source at the front end experiences a step jump.

8. The cryogenic measurement method based on pulse phase interleaving according to claim 1, characterized in that, The resistance value is obtained by unbiased weighted averaging. for: In the formula, V' is the weighting coefficient for the first sampling channel; A The voltage after compensation for the first sampling channel; V' is the weighting coefficient for the second sampling channel; B The voltage after compensation for the second sampling channel; This refers to the amplitude of the pulse current. This represents the noise variance of the second sampling channel; This represents the noise variance of the second sampling channel.

9. A cryogenic measurement system based on pulse phase interleaving, characterized in that, include: The calibration module is used to calibrate and correct the mismatch between the two sampling channels of the measurement system, obtain the zero-point bias voltage, system gain difference and sampling timing offset, and compensate the measured voltage based on the zero-point bias voltage and system gain difference. The pulse constant current source module is used to set the parameters of the measurement system and configure the pulse phase, so that the pulse constant current source module of the measurement system outputs two pulses with the same amplitude but staggered phase. The ADC sampling module is used to synchronize the sampling timing. The sampling points of each sampling channel are synchronized to the stable plateau region of its pulse, avoiding the edge region of the pulse. The data processing module is used to perform an unbiased weighted average of the sampled values ​​from the two sampling channels and obtain the measured temperature based on the resistance-temperature curve.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the cryogenic measurement method based on pulse phase interleaving as described in any one of claims 1-8.

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