Time-Interleaved ADC Clock Skew Calibration for High SNR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Timing mismatches in clock signals in ADCs limit the signal-to-noise ratio of the ADCs, especially in high-speed applications, where clock skew detection is affected by NOx and SO2.
Innovation Solution
The proposed calibration technique combines foreground and background calibration to improve clock skew detection in time-interleaved analog-to-digital converters (ADCs), using a calibration circuit to determine and compensate for clock skew by integrating foreground and background calibration techniques, thereby enhancing the signal-to-noise ratio and reducing power overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time-interleaved ADC structure is used to increase data rate, then productivity is improved, but timing mismatches among clock signals worsen the signal-to-noise ratio
Solution Approach 1:
The patent applies preliminary action by performing foreground calibration before the ADC operates in its normal mode. During this preliminary phase, a calibration signal is injected and processed to determine clock skew mismatches among the time-interleaved sub-ADCs. This advance calibration establishes correction values that are then applied during normal operation, allowing the system to achieve high data rates while maintaining signal-to-noise ratio through pre-established timing corrections.
2Measurement precision
If clock skew detection is performed in high-speed applications, then measurement precision is improved, but detection accuracy worsens due to NOx and SO2 interference
Solution Approach 1:
The patent extracts the clock skew detection function into a separate calibration mode that operates independently from the normal high-speed conversion mode. By injecting a known calibration signal and processing it through a dedicated calibration path, the system can accurately measure clock skew without the interference of noise factors present during normal operation. This separation allows precise measurement of timing mismatches that would otherwise be obscured by noise in high-speed applications.
3Device complexity
If traditional calibration techniques are used, then device complexity is reduced, but calibration accuracy worsens due to dynamic variations in clock skew
Solution Approach 1:
The patent implements dynamics by enabling the ADC to switch between two operational modes: calibration mode and normal conversion mode. The system dynamically adjusts its operation based on the need for calibration versus data processing. During calibration mode, the system performs accurate skew measurements and updates correction values. During normal mode, it applies these corrections while maintaining high-speed operation. This dynamic switching allows the system to achieve both calibration accuracy and high productivity without requiring overly complex continuous calibration mechanisms.
Data Source
AI summary
An analog-to-digital converter, ADC, is provided. The ADC comprises multiple time-interleaved sub-ADCs, a detection circuit, and a calibration circuit. The sub-ADCs are configured to, when the ADC is in a calibration mode, generate a first signal by sampling a calibration signal based on a first clock signal and at least a second clock signal. The first clock signal comprises a phase shift relative to the second clock signal. The calibration circuit is configured to determine a first mismatch between the phase shift and a phase shift threshold based on the first signal. The detection circuit is configured to, when the ADC is in an operation mode, generate a second signal by sampling one of a biased signal to be received by the sub-ADCs or a second calibration signal based on at least one of the first clock signal and the second clock signal. The calibration circuit is configured to determine a second mismatch between the phase shift and the phase shift threshold based on the second signal and calibrate the ADC based on the first and the second mismatch.