Time-Interleaved ADC Calibration Using Spectrum Image Minimization
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Solution Overview
Problem
Time-interleaved analog-to-digital converters (ADCs) face challenges in controlling and compensating for mismatches such as offset, gain, and timing errors, which affect their performance and throughput in high-speed applications.
Innovation Solution
A system and method for determining and updating calibration data, including gain error and time-offset calibration data, using a gradient-based optimization approach, where a calibration signal is applied to parallel ADCs to analyze output spectra and determine optimized calibration values, which are then used to correct mismatches and minimize image power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time-interleaved architecture is used to improve ADC throughput, then productivity increases, but device complexity increases due to multiple parallel ADCs requiring coordination
Solution Approach 1:
The ADC system is divided into multiple parallel time-interleaved ADCs, each operating at a fraction of the total sample rate. This segmentation allows the system to achieve high throughput by distributing the conversion workload across multiple channels while maintaining manageable complexity through modular architecture.
Solution Approach 2:
A feedback mechanism is implemented where the output of parallel ADCs is analyzed to determine calibration values for gain error and time-offset compensation. The system continuously monitors performance metrics and adjusts calibration parameters to maintain optimal operation, resolving the complexity issue through automated control.
2Productivity
If multiple parallel ADCs are used to increase sample rate, then productivity improves, but manufacturing precision deteriorates due to mismatch control challenges
Solution Approach 1:
Calibration is performed in advance to determine gain error and time-offset values for each ADC channel before normal operation. By pre-characterizing each channel's deviations and storing correction values, the system compensates for manufacturing variations without requiring ultra-precise matching during production.
Solution Approach 2:
The system changes operational parameters by applying calibration factors to adjust gain and timing of each ADC channel. Through digital signal processing, the system dynamically modifies effective parameters to compensate for physical variations, achieving high precision output despite manufacturing tolerances.
3Measurement precision
If calibration data is determined using gradient-based optimization, then measurement precision improves, but device complexity increases due to additional processing requirements
Solution Approach 1:
The system performs self-calibration by automatically analyzing its own output and determining correction values without external intervention. The gradient-based optimization algorithm processes ADC output signals to extract calibration information, enabling the system to self-correct for gain and timing errors while maintaining measurement precision.
Data Source
AI summary
Approaches provide for calibrating high speed analog-to-digital converters (ADCs). For example, a calibration signal can be applied to parallel ADCs. The output of the parallel ADCs can be analyzed using a gradient-based optimization approach or other such optimization approach to determine optimized gain error calibration data to compensate for gain mismatch in and between individual parallel time-interleaved ADCs and to determine time-offset calibration data to compensate for timing errors in and between individual parallel time-interleaved ADCs. For example, once a calibration signal is applied to an ADC, the output of the ADC can be analyzed to determine a spectrum of the calibration signal. One or more images (e.g., phasors) of the spectrum can be determined and used to determine initial values of the optimization. Thereafter, the optimization approach can be utilized to determine optimized gain error calibration data and optimized time-offset calibration data, which can be stored and/or used to calibrate individual time-interleaved ADCs.