Time-Interleaved ADC Sampling Calibration Using Linear Interpolation
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Solution Overview
Problem
Time-interleaved analog-to-digital converters (ADCs) face performance degradation due to manufacturing variations causing gain and sampling time mismatches between sub-channels, leading to narrow input signal bandwidth and hardware implementation challenges, especially with traditional fractional delay filtering methods.
Innovation Solution
A calibration method using linear interpolation and a calibration system for sampling time adaptation in time-interleaved ADCs, which estimates mismatching delays and calculates calibration slopes to compensate for sub-channel mismatches, employing a delay calibration coefficient for improved signal suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fractional delay filtering methods are used for calibration, then sampling time mismatching can be corrected, but input signal bandwidth becomes narrow and hardware implementation becomes complex
Solution Approach 1:
The patent extracts only the essential calibration information (slope and intercept parameters) from the linear relationship between sub-channel outputs, rather than implementing complete fractional delay filters. This extraction approach maintains calibration precision while dramatically reducing hardware complexity by removing unnecessary filtering components.
Solution Approach 2:
The patent transforms the calibration problem from requiring complex fractional delay filter parameters to using simple linear parameters (slope and intercept). By changing the parameter representation from filter coefficients to linear regression parameters, the solution achieves the same calibration function with much simpler hardware implementation.
2Adaptability or versatility
If advanced calibration algorithms are used to increase input signal bandwidth, then bandwidth is improved, but system complexity and hardware implementation challenges increase
Solution Approach 1:
The patent changes the calibration parameters from complex frequency-dependent filter coefficients to simple linear parameters (slope and intercept). This parameter transformation enables the system to handle broader input signal bandwidths while keeping the algorithm and hardware implementation simple and tractable.
Solution Approach 2:
The patent uses a simplified linear model that copies the essential calibration function from complex fractional delay filters. By creating this simplified copy with only slope and intercept parameters, the system achieves bandwidth improvement without inheriting the complexity of the original filter-based approach.
3Productivity
If multiple sub-channels are used to increase sampling rate, then effective sampling rate is boosted, but manufacturing variations cause gain and sampling time mismatching that degrades performance
Solution Approach 1:
The patent implements a feedback mechanism where the output signals from multiple sub-channels are compared and used to calculate calibration parameters (slope and intercept). This feedback loop continuously compensates for manufacturing variations in gain and sampling time, maintaining high ADC performance despite the use of multiple sub-channels for increased sampling rate.
Solution Approach 2:
The patent merges the calibration functions of multiple sub-channels into a unified linear model. By combining the output signals and applying linear regression to determine common calibration parameters, the system corrects individual sub-channel mismatches while maintaining the high sampling rate achieved through parallel sub-channel operation.
Data Source
AI summary
A calibration method and a calibration system for sampling time adaptation in a time-interleaved ADC, a medium, and a calibrator are provided. The calibration method comprises receiving a mismatching delay of one of sub-channels in the ADC sampling a same input signal, wherein a first sub-channel among the sub-channels is a reference channel that does not require calibration, and wherein in one sampling period, the mismatching delay of each of the remaining sub-channels is estimated based on the reference channel; receiving a sampling signal of a current sub-channel to be calibrated, wherein the current sub-channel is selected by a multiplexer; and calculating a calibration slope of the sampling signal of the current sub-channel by using a linear interpolation algorithm, and obtaining a calibrated sampling signal output by the current sub-channel, based on the mismatching delay of the current sub-channel, the calibration slope and a delay calibration coefficient.