Time-Interleaved ADC Error Correction for Order-Dependent Mismatch
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Solution Overview
Problem
Time-interleaved analog-to-digital converters (ADCs) face significant performance degradation due to mismatches between sub-ADCs, leading to order-dependent mismatch errors that vary based on the selection pattern and interaction between sub-ADCs, affecting dynamic range and signal quality.
Innovation Solution
The implementation of randomized sub-ADC selection patterns and advanced error calibration mechanisms, including order-dependent error estimation and compensation, to measure and reduce mismatches, spreading discrete error tones into the noise floor and correcting for order-dependent errors using error coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple sub-ADCs are time-interleaved to increase sampling speed, then productivity increases, but mismatch errors between sub-ADCs degrade measurement precision
Solution Approach 1:
The patent applies preliminary action by measuring and storing order-dependent error coefficients before actual conversion operations. The system pre-characterizes each sub-ADC's mismatch behavior under different ordering conditions, then uses these pre-measured coefficients to correct errors during normal operation, thereby maintaining high sampling speed while improving measurement precision
Solution Approach 2:
The patent changes the parameter representation by introducing order information as an additional dimension to characterize mismatch errors. Instead of using fixed mismatch coefficients, the system varies the error coefficients based on the ordering pattern of sub-ADC selections, allowing dynamic adaptation to different interleaving sequences and reducing overall mismatch errors
2Reliability
If randomized sub-ADC selection is used to reduce distortion, then signal quality improves, but order-dependent mismatch errors increase device complexity
Solution Approach 1:
The patent segments the mismatch error correction into two distinct parts: order-independent mismatch coefficients and order-dependent error coefficients. This segmentation allows the system to handle randomized selection patterns by adding only the necessary order-dependent component, rather than redesigning the entire correction mechanism, thus managing device complexity while improving signal quality
Solution Approach 2:
The patent introduces order information as an intermediary element that mediates between the randomized sub-ADC selection and the error correction process. This intermediary carries the necessary contextual information about selection patterns, enabling the system to apply appropriate corrections without requiring complex real-time analysis of the entire selection history
3Stability of the object's composition
If order-dependent error coefficients are measured and applied, then dynamic range improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies self-service by having the system measure its own error coefficients using internal test signals and self-characterization procedures. The ADC system performs self-diagnosis and self-calibration, reducing the need for external high-precision measurement equipment and lowering manufacturing precision requirements while still achieving improved dynamic range
Data Source
Figure 1A~1B
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AI summary
A time-interleaved analog-to-digital converter (ADC) uses M sub-analog-to-digital converters (sub-ADCs) to, according to a sequence, sample an analog input signal to produce digital outputs. When the M sub-ADCs are interleaved, the digital outputs exhibit mismatch errors between the M sub-ADCs due to mismatches between the sub-ADCs. A more second order subtle effect is that the mismatch error for a particular digital output from a particular ADC, due to internal coupling or other such interaction and effects between the M sub-ADCs, can vary depending on which sub-ADC(s) were used before and/or after the particular sub-ADC. If M sub-ADCs are time-interleaved randomly, the mismatches between the M sub-ADCs become a function of the sub-ADC selection pattern in the sequence. The present disclosure describes mechanisms for measuring and reducing these order-dependent mismatches to achieve high dynamic range performance in the time-interleaved ADC.