Time-Interleaved ADC Timing Calibration via Correlation Feedback

The patent implements a feedback mechanism where the computing unit calculates time skew values based on correlation between samples from different ADCs, generates calibration codes, and feeds them back to delay elements that adjust the timing of ADC operations. This closed-loop feedback continuously corrects time skew errors, allowing the system to maintain high sampling frequencies while compensating for timing errors that would otherwise degrade conversion performance.

The patent dynamically changes the delay parameter of delay elements based on calculated time skew values. By adjusting the delay parameter in response to measured timing errors, the system adapts to variations in ADC sampling timing while maintaining the high-speed time-interleaved operation. This parameter adjustment allows correction of time skew without reducing the overall sampling frequency.

The patent enables continuous calibration by computing correlation values and time skew measurements using normally acquired signal samples during ongoing conversion operations. The computing unit processes samples that would otherwise be discarded or used for primary conversion, allowing calibration computations to proceed continuously without interrupting the main analog-to-digital conversion workflow. This maintains both timing accuracy and operational continuity.

The computing unit serves multiple functions: it processes samples for primary conversion purposes while simultaneously performing calibration computations using the same sample data. By making the calibration system multi-functional and capable of operating on existing signal paths, the patent eliminates the need for separate calibration modes that would interrupt normal conversion operations.

The patent divides the calibration task into independent per-ADC operations where each ADC's time skew is calibrated separately using its own samples and the samples of adjacent ADCs. The computing unit processes each ADC independently, calculating correlation values and time skew values for individual converters. This segmentation allows the system to scale to multiple ADCs without requiring complex inter-dependent calibration procedures, managing the increased complexity through modular independent calibration of each channel.

The patent introduces correlation values as an intermediary computational step that simplifies the relationship between multiple ADCs. By computing correlation between samples from different ADCs and using these correlation values to derive time skew measurements, the system creates a standardized intermediate representation that facilitates calibration across multiple converters. This intermediary approach provides a systematic method for handling the increased complexity of multi-ADC calibration.