Lookup-Table ADC Calibration for High-Speed Linearity
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Solution Overview
Problem
High-speed analog-to-digital converters require efficient calibration methods to address non-linearities while minimizing power and area requirements, especially in radio-frequency sampling receivers.
Innovation Solution
A lookup-table-based analog-to-digital converter system that uses a digital-to-analog converter to generate calibration voltages, an analog-to-digital converter to generate digital output codes, and a lookup table to store and retrieve these codes, allowing for efficient calibration and operation in high-speed analog-to-digital conversion modes without complex mathematical functions or hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used in high-speed ADCs, then measurement precision can be maintained, but power consumption and area requirements increase
Solution Approach 1:
The patent implements calibration during idle periods or transition phases before actual high-speed conversion begins. The lookup table is pre-computed and stored, so when conversion is needed, the system can immediately use the pre-calibrated data without consuming additional power during the conversion process itself.
Solution Approach 2:
Instead of performing complex real-time mathematical calculations to correct non-linearities, the patent creates a lookup table that copies and stores pre-computed correction data. During operation, the system simply retrieves values from this table rather than recalculating corrections, dramatically reducing power consumption while maintaining precision.
2Measurement precision
If complex mathematical functions and hardware are used for calibration, then linearity can be improved, but device complexity increases
Solution Approach 1:
The patent extracts the complex mathematical correction functions from the real-time conversion path and separates them into a pre-computation phase. The actual conversion hardware only needs to perform simple table lookups and basic arithmetic, while the complex polynomial calculations are performed once during calibration and stored as lookup table data.
Solution Approach 2:
All complex mathematical operations for correcting non-linearities are performed in advance during a calibration phase. The results are stored in a lookup table, so the main conversion circuitry doesn't need complex mathematical hardware, reducing device complexity while maintaining linearity accuracy.
3Productivity
If high-speed operation is implemented, then productivity increases, but maintaining linearity becomes more difficult
Solution Approach 1:
The system performs comprehensive linearity calibration and generates the lookup table before high-speed operation begins. This preliminary calibration captures all non-linear characteristics, allowing the fast converter to maintain accuracy by referencing pre-computed correction data rather than performing slow real-time corrections.
Solution Approach 2:
The patent copies correction data into a lookup table that can be rapidly accessed during high-speed conversion. This allows the system to maintain linearity without the computational overhead of real-time mathematical corrections, enabling both high speed and high precision.
Data Source
AI summary
An analog-to-digital converter system includes a digital-to-analog converter for generating calibration voltages based on digital input codes, and an analog-to-digital converter, connected to the digital-to-analog converter, for receiving the calibration voltages from the digital-to-analog converter, for receiving sampled voltages, for generating digital output codes based on the calibration voltages, and for generating digital output codes based on the sampled voltages. The analog-to-digital converter system may have a lookup table, connected to the analog-to-digital converter, for storing the first digital output codes in association with the digital input codes. A method of calibrating an analog-to-digital converter system is also disclosed.