Digital calibration method applied to sampling time mismatch of time-interleaved ADC

Abstract

The invention discloses an all-digital calibration method applied to sampling time mismatch of a time-interleaved ADC, and belongs to the field of ADC sampling clock skew calibration. According to the method, digital codes of two adjacent channels are extracted to obtain autocorrelation functions of the two channels, and the autocorrelation functions of the adjacent channels are subtracted and then are subjected to Taylor expansion, so that the sampling time mismatch of the two channels is obtained; obtaining the product of the clock skew term and the derivative of the autocorrelation function; and on the basis of a bilateral approximation principle, approximate calculation is performed on the derivative of the autocorrelation function to obtain a more accurate derivative of the autocorrelation function, so that the value of a clock skew item of each channel is obtained, and a real clock skew variable is obtained through matrix operation to calibrate the digital code of the multi-channel ADC. Compared with the prior art, the method provided by the invention can realize digital calibration with higher precision and higher bandwidth. In a multichannel time interleaving application scene with harsh requirements on calibration precision and calibration bandwidth, the method has remarkable advantages.

Description

Technical Field

[0001] The present invention belongs to the field of ADC sampling clock deviation calibration, and more particularly, relates to a digital calibration method for time-interleaved ADC sampling time mismatch. Background Art

[0002] In today's broadband cable and satellite communications, the input spectrum ranges from tens of megahertz to several gigahertz. ADCs directly digitize the RF signal and then send it to a DSP. However, direct sampling architectures were impractical for the past decade. The primary limitation was the extremely high sampling rate required of the converter. However, with increasingly advanced technology, high-speed ADCs are now feasible. In today's broadband cable and satellite communications, the input spectrum ranges from tens of megahertz to several gigahertz. Therefore, Nyquist-rate converters in the GS / s range are required to sample the input signal within its full bandwidth.

[0003] However, this architecture is susceptible to mismatches between ADC channels, including offset, gain, and timing mismatches. Compared to offset and gain mismatches, timing mismatches introduce dynamic errors proportional to the input frequency and amplitude. Calibration algorithms are generally categorized into two types: foreground calibration and background calibration. Foreground calibration is simpler but requires interrupting normal ADC operation and cannot track power supply and voltage variations. While background calibration is more complex than foreground calibration, it can proactively track power supply and temperature variations without interrupting normal operation.

[0004] Background calibration is divided into mixed digital-analog calibration and fully digital calibration. Mixed digital-analog calibration uses a variable delay line to control the sampling clock, forming a feedback loop. However, using a variable delay line to control the sampling clock inevitably introduces clock jitter, which can significantly impact ADC accuracy in high-speed ADCs. In contrast, fully digital calibration algorithms, while incurring greater hardware overhead, do not introduce jitter and directly process the digital code.

[0005] like Figure 1 The figure shows the traditional all-digital calibration algorithm. Taking two channels as an example, the traditional all-digital calibration algorithm uses the autocorrelation function to obtain the variables related to the clock deviation. Then use the differentiator to get the derivative of the autocorrelation function Use the multiplier to and Multiplication can obtain the true clock deviation ΔT, and finally Taylor expansion can be used to obtain the final calibrated digital code.

[0006] However, when this scheme is used to find the autocorrelation derivative, the derivative actually obtained is at τ = Ts Derivative at +ΔT, T s is the sampling interval between the two channels. In fact, there will be a certain deviation. When the frequency increases, the accuracy of the calibration algorithm decreases. Especially when the number of channels increases, the calibration algorithm also needs to be calibrated in steps, such as Figure 2 As shown in the figure. When the number of channels is four, the third channel must be calibrated using the first reference channel. After the third channel is calibrated, the second and fourth channels are calibrated using the first reference channel and the calibrated third channel. With four channels, two calibration steps are required. As the number of channels increases, the number of calibration steps also increases. Summary of the Invention

[0007] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a digital calibration method for time-interleaved ADC sampling time mismatch. This method can directly perform one-step calibration through the autocorrelation function between two adjacent channels, and at the same time use bilateral approximation to obtain a more accurate autocorrelation derivative, thereby obtaining a more accurate clock deviation of each channel, thereby achieving higher calibration accuracy and wider bandwidth.

[0008] To achieve the above object, according to a first aspect of the present invention, a digital calibration method for time-interleaved ADC sampling time mismatch is provided, comprising:

[0009] S1, calculate the autocorrelation function between two adjacent channels; where the i-th channel is adjacent to the i+1-th channel, i = 1, 2, ..., N-1, N is the total number of channels; when i = 1, the autocorrelation function R i,i+1 =R(T s +Δt i+1 ); when i≠1, R i,i+1 =R(T s +Δt i+1 -Δt i ); The Nth channel is adjacent to the first channel, and the autocorrelation function R N,1 =R(T s -Δt N );Δt i , Δt N are the clock deviations of the ith and Nth channels respectively, T s is the sampling interval between the i-th channel and the i+1-th channel, and between the N-th channel and the first channel;

[0010] S2: Take the i-th channel and the i+1-th channel as the i-th group of channels. When i=1,2,…,N-2, the autocorrelation function of the i-th group of channels is subtracted from the autocorrelation function of the i+1-th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function. A i =2Δt i+1 -Δt i+2 -Δt i ;

[0011] The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and A N-1 =2Δt N -Δt N-1 ;

[0012] S3, derive the derivatives of the respective correlation functions, and approximate the derivatives of the respective correlation functions based on the bilateral approximation principle; where i = 1, 2, ..., N-2, When i=N-1, And divide the product of each clock deviation term and the derivative of the autocorrelation function in S2 by the approximate calculated value of the derivative of the corresponding autocorrelation function to obtain A i With A N-1 The value of , thus solving Δt i , Δt N ;

[0013] S4, according to Δt i , Δt N Calibrate each corresponding channel.

[0014] According to a second aspect of the present invention, there is provided a digital calibration apparatus for time-interleaved ADC sampling time mismatch, comprising:

[0015] The clock error extraction module is used to calculate the autocorrelation function between two adjacent channels; where the i-th channel is adjacent to the i+1-th channel, i = 1, 2, ..., N-1, N is the total number of channels; when i = 1, the autocorrelation function R i,i+1 =R(T s +Δt i+1 ); when i≠1, R i,i+1 =R(T s +Δt i+1 -Δt i ); The Nth channel is adjacent to the first channel, and the autocorrelation function R N,1 =R(T s -Δt N);Δt i , Δt N are the clock deviations of the ith and Nth channels respectively, T s is the sampling interval between the i-th channel and the i+1-th channel, and between the N-th channel and the first channel;

[0016] The i-th channel and the i+1-th channel are regarded as the i-th group of channels. When i=1,2,…,N-2, the autocorrelation function of the i-th group of channels is subtracted from the autocorrelation function of the i+1-th group of channels and Taylor expansion is performed to obtain the product of the clock deviation term and the derivative of the autocorrelation function. A i =2Δt i+1 -Δt i+2 -Δt i ;

[0017] The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and A N-1 =2Δt N -Δt N-1 ;

[0018] The autocorrelation function derivation module is used to approximate the derivatives of the respective correlation functions based on the bilateral approximation principle; where i = 1, 2, ..., N-2, When i=N-1, And divide the product of each clock deviation term and the derivative of the autocorrelation function in S2 by the approximate calculated value of the derivative of the corresponding autocorrelation function to obtain A i With A N-1 The value of

[0019] Matrix multiplication module, used to calculate the matrix according to A i With A N-1 Calculate Δt by i , Δt N ;

[0020] Calibration module for i , Δt N Calibrate each corresponding channel.

[0021] According to a third aspect of the present invention, there is provided an electronic device comprising: a computer-readable storage medium and a processor;

[0022] The computer-readable storage medium is used to store executable instructions;

[0023] The processor is configured to read the executable instructions stored in the computer-readable storage medium and execute the method according to the first aspect.

[0024] According to a fourth aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to execute the method according to the first aspect.

[0025] According to a fifth aspect of the present invention, there is provided a computer program product comprising a computer program or instructions, which implement the method according to the first aspect when executed by a processor.

[0026] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0027] At the same time, in order to avoid the need for step-by-step calibration, the calibration method adopted here is to use two adjacent channels for calibration, which can avoid step-by-step calibration. That is to say, no matter how many channels there are, only one-step calibration is required.

[0028] It can be seen from this that a more accurate derivative of the autocorrelation function can be obtained through bilateral approximation, and adjacent channels can be used for calibration, so that step-by-step calibration can be avoided when there are multiple channels.

[0029] This enables more accurate and wider bandwidth calibration while avoiding the step-by-step calibration required in traditional calibration algorithms.

[0030] (1) The fully digital calibration method implemented by the present invention directly extracts the clock deviation through the autocorrelation function between two adjacent channels, and does not require step-by-step calibration, but can be calibrated in one step.

[0031] (2) The all-digital calibration method implemented by the present invention utilizes the principle of bilateral approximation to obtain a more accurate derivative of the autocorrelation function, thereby obtaining a more accurate clock deviation in each channel.

[0032] (3) Compared with the mixed digital-analog calibration algorithm, the all-digital calibration method implemented by the present invention has stronger portability and better robustness in hardware implementation, while avoiding the clock jitter caused by the variable delay line. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the block diagram of the existing traditional two-channel sampling time mismatch full digital calibration algorithm; Z in the figure -1 is the unit delay, ABS is the absolute value operation, DF is the differentiator, and MA is the averaging filter;

[0034] Figure 2 This is a schematic diagram of the existing traditional four-channel step-by-step calibration;

[0035] Figure 3 A schematic diagram of a differentiator circuit provided by an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of a four-channel one-step calibration according to an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of a four-channel time-interleaved ADC sampling according to an embodiment of the present invention;

[0038] Figure 6 A structural diagram of a fully digital calibration device for four-channel sampling time mismatch provided by an embodiment of the present invention;

[0039] Figure 7 A schematic diagram showing spectrum comparison before and after calibration of a four-channel time-interleaved ADC according to an embodiment of the present invention;

[0040] Figure 8 A schematic diagram of bandwidth calibration for a four-channel time-interleaved ADC according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0042] An embodiment of the present invention provides a digital calibration method for time-interleaved ADC sampling time mismatch, comprising:

[0043] S1, calculate the autocorrelation function between two adjacent channels; where the i-th channel is adjacent to the i+1-th channel, i = 1, 2, ..., N-1, N is the total number of channels; when i = 1, the autocorrelation function R i,i+1 =R(T s +Δt i+1 ); when i≠1, R i,i+1 =R(T s +Δt i+1 -Δt i ); The Nth channel is adjacent to the first channel, and the autocorrelation function R N,1 =R(T s -Δt N );Δt i , Δt N are the clock deviations of the ith and Nth channels respectively, T sIt is the sampling interval between the i-th channel and the i+1-th channel, and between the N-th channel and the first channel.

[0044] Furthermore, step S1 includes: extracting the digital codes of the i-th channel and the i+1-th channel within a preset sampling period and subtracting them, accumulating the values ​​obtained after the subtraction and averaging them to obtain the autocorrelation function R of the i-th channel and the i+1-th channel. i,i+1 ; Extract the digital codes of the Nth channel and the first channel within the preset sampling period and subtract them, accumulate the values ​​obtained after subtraction and calculate the average to obtain the autocorrelation function R of the Nth channel and the first channel N,1 .

[0045] S2: Take the i-th channel and the i+1-th channel as the i-th group of channels. When i=1,2,…,N-2, the autocorrelation function of the i-th group of channels is subtracted from the autocorrelation function of the i+1-th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function. A i =2Δt i+1 -Δt i+2 -Δt i ;

[0046] The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and A N-1 =2Δt N -Δt N-1 ;

[0047] S3, derive the derivatives of the respective correlation functions, and approximate the derivatives of the respective correlation functions based on the bilateral approximation principle; where i = 1, 2, ..., N-2, When i=N-1, And divide the product of each clock deviation term and the derivative of the autocorrelation function in S2 by the approximate calculated value of the derivative of the corresponding autocorrelation function to obtain A i With A N-1 The value of , thus solving Δt i , Δt N ;

[0048] S4, according to Δt i , Δt N Calibrate each corresponding channel.

[0049] Specifically, in step S1 , the digital codes of adjacent channels are subtracted, and then the absolute values ​​of the obtained values ​​are taken and accumulated and averaged, so as to obtain the autocorrelation functions of the adjacent channels.

[0050] Among them, the i-th channel is adjacent to the i+1-th channel, i=1,2,…,N-1, N is the total number of channels;

[0051] When i=1, the autocorrelation function R between the i-th channel and the i+1-th channel is i,i+1 =R(T s +Δt i+1 );

[0052] When i≠1, the autocorrelation function R between the i-th channel and the i+1-th channel i,i+1 =R(T s +Δt i+1 -Δt i );

[0053] The Nth channel is adjacent to the first channel, and the autocorrelation function R between the Nth channel and the first channel is N,1 =R(T s -Δt N ).

[0054] Taking four channels as an example, the digital codes of adjacent channels are first subtracted, and then the absolute values ​​of the obtained values ​​are taken and accumulated and averaged to obtain the autocorrelation function of the adjacent channels, as shown below:

[0055] R 12 =R(T s +Δt2) (1)

[0056] R 23 =R(T s +Δt3-Δt2) (2)

[0057] R 34 =R(T s +Δt4-Δt3) (3)

[0058] R 41 =R(T s -Δt4) (4)

[0059] Where R(·) is the autocorrelation function.

[0060] In step S2, the autocorrelation functions of adjacent channels are subtracted to obtain the product of the derivative of the autocorrelation function and the clock deviation.

[0061] Among them, the i-th channel and the i+1-th channel are regarded as the i-th group channel. When i=1,2,…,N-2, the autocorrelation function of the i-th group channel is subtracted from the autocorrelation function of the i+1-th group channel and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function. Let Ai =2Δt i+1 -Δt i+2 -Δt i ;

[0062] The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and Let A N-1 =2Δt N -Δt N-1 .

[0063] Taking four channels as an example, by subtracting the autocorrelation functions of adjacent channels, we can obtain the product of the derivative of the autocorrelation function between each channel and the clock deviation. At the same time, Taylor expansion is performed to obtain the following formula:

[0064]

[0065] Similarly, the autocorrelation functions between other channels can be used to obtain the following expressions:

[0066]

[0067] Among them, let A1=2Δt2-Δt3, A2=2Δt3-Δt4-Δt2, and A3=2Δt4-Δt3.

[0068] In step S3, the autocorrelation function is passed through a differentiator to obtain the derivative of the autocorrelation function. The differentiator is composed of a digital filter (such as Figure 3 The tap coefficient of the digital filter shown is 25, and the tap coefficient can be appropriately selected according to the hardware calculation cost and calculation accuracy. It is equivalent to a differentiator, and the derivative of the corresponding autocorrelation function can be obtained through this digital filter. Then, based on the principle of bilateral approximation:

[0069] f(x+Δx)+f(x-Δx)=2f(x) (8)

[0070] A more accurate derivative of the autocorrelation function can be obtained:

[0071]

[0072] Taking four channels as an example, the more accurate derivative of the autocorrelation function is:

[0073]

[0074] Then, the product of the derivative of the autocorrelation function and the clock bias is added to the derivative of the autocorrelation function. By dividing, we can get the values ​​of variables A1, A2, and A3 related to the clock deviation of each channel. Then, through matrix multiplication, we can get the clock deviation Δt2, Δt3, and Δt4 corresponding to each channel. The matrix multiplication formula is:

[0075]

[0076] Taking four channels as an example, the matrix multiplication formula is:

[0077]

[0078] In step S4, according to the clock deviation Δt corresponding to each channel i , Δt N , calibrate each corresponding channel. The principle of calibration is to use the digital code value output by each channel, the differential of the digital code value output by each channel and the clock deviation Δt through the first-order Taylor expansion method to obtain the digital code value after calibration. The calibration formula is:

[0079]

[0080] is the digital code value after channel calibration, and y is the digital code value before channel calibration.

[0081] Take four channels as an example, Figure 4-5 As shown, each corresponding channel is calibrated according to the clock deviations Δt2, Δt3 and Δt4 corresponding to each channel.

[0082] The digital calibration device for time-interleaved ADC sampling time mismatch provided by the present invention is described below. The digital calibration device for time-interleaved ADC sampling time mismatch described below and the digital calibration method for time-interleaved ADC sampling time mismatch described above can refer to each other.

[0083] An embodiment of the present invention provides a digital calibration device for time-interleaved ADC sampling time mismatch, comprising:

[0084] The clock error extraction module is used to calculate the autocorrelation function between two adjacent channels; where the i-th channel is adjacent to the i+1-th channel, i = 1, 2, ..., N-1, N is the total number of channels; when i = 1, the autocorrelation function R i,i+1 =R(T s +Δt i+1 ); when i≠1, R i,i+1 =R(T s +Δt i+1 -Δt i ); The Nth channel is adjacent to the first channel, and the autocorrelation function R N,1=R(T s -Δt N );Δt i , Δt N are the clock deviations of the ith and Nth channels respectively, T s is the sampling interval between the i-th channel and the i+1-th channel, and between the N-th channel and the first channel;

[0085] The i-th channel and the i+1-th channel are regarded as the i-th group of channels. When i=1,2,…,N-2, the autocorrelation function of the i-th group of channels is subtracted from the autocorrelation function of the i+1-th group of channels and Taylor expansion is performed to obtain the product of the clock deviation term and the derivative of the autocorrelation function. A i =2Δt i+1 -Δt i+2 -Δt i ;

[0086] The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and A N-1 =2Δt N -Δt N-1 ;

[0087] The autocorrelation function derivation module is used to approximate the derivatives of the respective correlation functions based on the bilateral approximation principle; where i = 1, 2, ..., N-2, When i=N-1, And divide the product of each clock deviation term and the derivative of the autocorrelation function in S2 by the approximate calculated value of the derivative of the corresponding autocorrelation function to obtain A i With A N-1 The value of

[0088] Matrix multiplication module, used to calculate the matrix according to A i With A N-1 Calculate Δt by i , Δt N ;

[0089] Calibration module for i , Δt N Calibrate each corresponding channel.

[0090] Taking four channels as an example, the digital calibration device for time-interleaved ADC sampling time mismatch provided by the embodiment of the present invention is as follows: Figure 6 shown.

[0091] like Figure 7As shown in the figure, when the number of channels is 4, the sampling rate is 4G and the clock deviation is 0.5%, the effective accuracy ENOB before calibration is only 5.76bit. However, after calibration by the all-digital calibration method proposed in the present invention, the effective accuracy ENOB reaches 7.77bit, indicating that the calibration algorithm provided by the present invention has a very significant effect.

[0092] like Figure 8 As shown in the figure, when the frequency of the input signal becomes higher, the uncalibrated ENOB continues to decrease. After calibration by the all-digital calibration method proposed in the present invention, it can be seen that the calibration effect is very good in the entire frequency band, and high-precision and high-bandwidth calibration is achieved.

[0093] In summary, the present invention can directly perform one-step calibration through the autocorrelation function between two adjacent channels, and at the same time, using the double-sideband approximation method, it can obtain more accurate clock deviations of each channel, thereby achieving higher calibration accuracy and larger bandwidth.

[0094] An embodiment of the present invention provides an electronic device, comprising: a computer-readable storage medium and a processor;

[0095] The computer-readable storage medium is used to store executable instructions;

[0096] The processor is configured to read the executable instructions stored in the computer-readable storage medium and execute the method described in any one of the above embodiments.

[0097] An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to execute the method described in any of the above embodiments.

[0098] An embodiment of the present invention provides a computer program product, including a computer program or instructions, which implements the method described in any of the above embodiments when executed by a processor.

[0099] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A digital calibration method for time-interleaved ADC sampling time mismatch, characterized in that: include: S1, calculate the autocorrelation function between two adjacent channels; where the i-th channel is adjacent to the i+1-th channel, i = 1, 2, ..., N-1, N is the total number of channels; when i = 1, the autocorrelation function R i,i+1 =R(T s +Δt i+1 ); when i≠1, R i,i+1 =R(T s +Δt i+1 -Δt i ); The Nth channel is adjacent to the first channel, and the autocorrelation function R N,1 =R(T s -Δt N );Δt i , Δt N are the clock deviations of the ith and Nth channels respectively, T s is the sampling interval between the i-th channel and the i+1-th channel, and between the N-th channel and the first channel; S2: Take the i-th channel and the i+1-th channel as the i-th group of channels. When i=1,2,…,N-2, the autocorrelation function of the i-th group of channels is subtracted from the autocorrelation function of the i+1-th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function. A i =2Δt i+1 -Δt i+2 -Δt i ; The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and A N-1 =2Δt N -Δt N-1 ; S3, derive the derivatives of the respective correlation functions, and approximate the derivatives of the respective correlation functions based on the bilateral approximation principle; where i = 1, 2, ..., N-2, When i=N-1, And divide the product of each clock deviation term and the derivative of the autocorrelation function in S2 by the approximate calculated value of the derivative of the corresponding autocorrelation function to obtain A i With A N-1 The value of , thus solving Δt i , Δt N ; S4, according to Δt i , Δt N Calibrate each corresponding channel.

2. The method according to claim 1, wherein In step S3, according to A i With A N-1 The value of Δt is solved by matrix multiplication. i , Δt N ; The calculation formula of the matrix multiplication is:

3. The method according to claim 1, wherein The calibration formula used in step S4 is: in, is the digital code value after channel calibration, y is the digital code value before channel calibration, and Δt is the clock deviation of the channel.

4. The method according to claim 1, wherein Step S1 includes: extracting the digital codes of the i-th channel and the i+1-th channel within a preset sampling period and subtracting them, accumulating the values ​​obtained after the subtraction and averaging them to obtain the autocorrelation function R of the i-th channel and the i+1-th channel. i,i+1 ; Extract the digital codes of the Nth channel and the first channel within the preset sampling period and subtract them. Accumulate the values ​​obtained after subtraction and calculate the average to obtain the autocorrelation function R of the Nth channel and the first channel. N,1 .

5. A digital calibration device for time-interleaved ADC sampling time mismatch, characterized in that: include: The clock error extraction module is used to calculate the autocorrelation function between two adjacent channels; where the i-th channel is adjacent to the i+1-th channel, i = 1, 2, ..., N-1, N is the total number of channels; when i = 1, the autocorrelation function R i,i+1 =R(T s +Δt i+1 ); when i≠1, R i,i+1 =R(T s +Δt i+1 -Δt i ); The Nth channel is adjacent to the first channel, and the autocorrelation function R N,1 =R(T s -Δt N );Δt i , Δt N are the clock deviations of the ith and Nth channels respectively, T s is the sampling interval between the i-th channel and the i+1-th channel, and between the N-th channel and the first channel; The i-th channel and the i+1-th channel are regarded as the i-th group of channels. When i=1,2,…,N-2, the autocorrelation function of the i-th group of channels is subtracted from the autocorrelation function of the i+1-th group of channels and Taylor expansion is performed to obtain the product of the clock deviation term and the derivative of the autocorrelation function. A i =2Δt i+1 -Δt i+2 -Δt i ; The Nth channel and the first channel are regarded as the Nth group of channels. When i=N-1, the autocorrelation function of the Nth group of channels is subtracted from the autocorrelation function of the N-1th group of channels and then Taylor expanded to obtain the product of the clock deviation term and the derivative of the autocorrelation function and A N-1 =2Δt N -Δt N-1 ; The autocorrelation function derivation module is used to approximate the derivatives of the respective correlation functions based on the bilateral approximation principle; where i = 1, 2, ..., N-2, When i=N-1, And divide the product of each clock deviation term and the derivative of the autocorrelation function in S2 by the approximate calculated value of the derivative of the corresponding autocorrelation function to obtain A i With A N-1 The value of Matrix multiplication module, used to calculate the matrix according to A i With A N-1 Calculate Δt by i , Δt N ; Calibration module for i , Δt N Calibrate each corresponding channel.

6. An electronic device, characterized in that: include: Computer-readable storage medium and processor; The computer-readable storage medium is used to store executable instructions; The processor is configured to read the executable instructions stored in the computer-readable storage medium and execute the method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to execute the method according to any one of claims 1 to 4.

8. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

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