TI-ADC Calibration Using Frequency-Modulated Sweep Signals
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Solution Overview
Problem
Conventional time-interleaved ADC calibration methods require long calibration times and increased circuit complexity due to the use of unmodulated CW signals, especially when high frequency resolution and wide bands are involved, leading to high costs.
Innovation Solution
An ADC calibration device using a frequency modulated wave with a predetermined frequency pattern within an applicable frequency range, incorporating a calibration signal generator, frequency converter, serial-parallel conversion, individual frequency detection units, mismatch calculation, and correction information units to calibrate TI-ADCs efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If unmodulated CW signals are used for calibration, then the calibration process is simple to implement, but the calibration time becomes excessively long for wide bands with high frequency resolution
Solution Approach 1:
The patent changes the frequency parameter of the calibration signal from static (unmodulated CW) to dynamic (frequency-modulated) to enable simultaneous coverage of wide frequency bands. The frequency modulation allows the calibration signal to sweep through the entire applicable frequency range, obtaining mismatch characteristics across the full band in a single calibration process rather than requiring multiple measurements at different frequencies.
2Measurement precision
If frequency switching is performed to obtain mismatch characteristics across the entire band, then the frequency resolution can be improved, but the calibration time increases significantly
Solution Approach 1:
The patent implements continuous frequency modulation of the calibration signal to maintain continuous coverage of the frequency band. Instead of discrete frequency switching that creates gaps and requires multiple measurements, the frequency-modulated signal continuously sweeps through the entire band, providing uninterrupted measurement data for calculating mismatch characteristics with high frequency resolution across the whole range.
3Measurement precision
If multiple frequency measurements are performed to cover the entire band, then the mismatch characteristics can be accurately obtained, but the circuit complexity and cost increase
Solution Approach 1:
The patent makes the single calibration signal generator perform multiple functions by modulating its frequency to cover the entire applicable frequency range. Instead of requiring separate measurement circuits or multiple signal sources for different frequency bands, the frequency-modulated calibration signal enables a single circuit configuration to obtain mismatch characteristics across the full band, reducing overall circuit complexity and cost.
Data Source
AI summary
In an ADC calibration device, the calibration signal generator generates a frequency modulated wave, as a calibration signal, in which frequency changes in a frequency pattern, which is predetermined, within an applicable frequency range over time. A TI-ADC outputs a sample signal obtained by performing an AD conversion of the calibration signal input. Individual frequency characteristic detection units are provided in parallel corresponding to the plurality of AD converters and individually detect frequency characteristics of the sample signal for each of the plurality of AD converters. In a control unit, a mismatch calculation unit calculates frequency characteristics of mismatch characteristics between the plurality of AD converters from the frequency characteristics of the sample signal for each of the plurality of AD converters, and calculates correction information for correcting a mismatch.