Method for correcting frequency response non-consistency error of TIADC system

Abstract

The invention discloses a TIADC system frequency response non-consistency error correction method based on a sampling reconstruction filter bank, and the method comprises the steps: firstly measuringthe frequency response of each ADC of a TIADC system, determining an ideal frequency response function, and calculating the frequency response of a sampling reconstruction filter through the ideal frequency response and the frequency response of each ADC; obtaining amplitude-frequency response and group delay according to the frequency response of the sampling reconstruction filter; designing a first-stage linear phase amplitude-frequency compensation filter bank according to amplitude-frequency, designing a second-stage all-pass filter bank and a third-stage fractional delay filter bank according to group delay, and calculating integral integer delay to form a sampling reconstruction filter bank by the three stages of filter banks; enabling actual sampling data to pass through a samplingreconstruction filter bank; determining the reconstructed sampling sequence corresponding to the actual sampling sequence according to the overall time delay, and finally calculating the corrected sampling sequence according to the actual sampling sequence and the reconstructed sampling sequence, so that the problem of frequency response non-consistency error correction of the TIADC system under large frequency response difference is solved.

Description

technical field [0001] The invention belongs to the technical field of time-domain testing, and more specifically relates to a TIADC system frequency response inconsistency error correction method based on a sampling reconstruction filter bank. Background technique [0002] In the scheme of building an ultra-high-speed acquisition system, the time-alternated ADC (TIADC) architecture has been widely used because of its simple implementation. Using M chip sampling rate f s The ADC of / M alternately samples the same signal in the time sequence at equal intervals, and the equivalent sampling rate can be obtained as f s sample data. Theoretically, when all ADCs are identical, this system has the same sampling rate as f s Equivalent to a single ADC acquisition system that produces an ideally sampled output. [0003] However, in the actual TIADC system, each ADC is not exactly the same; in addition, in order for the input signal to be sampled by all ADCs, analog devices (such a...

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Problems solved by technology

This will result in different frequency input signals, the errors generated by the TIADC system are not exactly the same, and the errors are frequency-dependent.

Based on such considerations, the patent CN108923784A and the patent CN108809308A respectively estimate the error of the full bandwidth from the amplitude and time, and use the point frequency method to correct the error at the maximum frequency point of the signal energy, but this method is still a point frequency correction in essence; Patent US7978104 writes the frequency response of the sampling channel in the form of a polynomial in the frequency domain, and uses a polynomial filter for reconstruction, but this method is only applicable to the case of regular frequency response. When the actual system frequency response is irregular, the frequency of the sampling channel The response will be difficult to write in the form of low-order polynomials, and the filter cannot be effectively designed

[0008] In summary, there is currently no general method that can correct the inconsistency error of the TIADC frequency response when the frequency response of the sampling channel is quite different.

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