Interleaved ADC Correction for Spurious-Free High Sampling
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Solution Overview
Problem
Interleave-type AD converting apparatuses with high sampling rates face issues due to non-linear characteristics of AD converters, leading to spurious components in output signals and reduced dynamic range when different converters have varying frequency characteristics.
Innovation Solution
The apparatus employs multiple AD converters with phase-differing sampling clocks and amplitude-dependent characteristic correcting sections that use correction factors to correct individual signals, ensuring the output signal has an ideal linear relationship between amplitude and data value, thereby eliminating spurious components and enhancing dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple AD converters with different frequency characteristics are used to achieve high sampling rates, then the sampling rate is improved, but spurious components appear in the output signal due to non-linear characteristics
Solution Approach 1:
The patent applies preliminary action by correcting the non-linear characteristics of each AD converter before combining their outputs. Correction tables are pre-calculated and stored, containing correction values for different amplitude levels. During operation, the correction values are retrieved and applied to each converter's output signal before interleaving, thereby eliminating spurious components while maintaining high sampling rates.
Solution Approach 2:
The patent applies local quality by providing individual correction processing for each AD converter based on its specific non-linear characteristics. Each converter's output is corrected using amplitude-dependent correction values that are specific to that converter's frequency characteristics, ensuring that local variations in converter performance are compensated for individually rather than using a uniform correction approach.
2Speed
If multiple AD converters with different non-linear characteristics are combined, then high sampling rates are achieved, but the dynamic range of the output signal decreases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction tables that contain amplitude-dependent correction values for each AD converter. These correction tables are generated based on the specific non-linear characteristics of each converter and are applied before the interleaving process, thereby preventing spurious components from degrading the dynamic range while maintaining high sampling rates.
Solution Approach 2:
The patent applies parameter changes by using amplitude-dependent correction values that vary according to the signal amplitude. The correction tables store different correction parameters for different amplitude levels, allowing the system to dynamically adjust the correction applied to each sample based on its amplitude, thereby optimizing the dynamic range across the entire signal range.
Data Source
AI summary
Provided is an AD converting apparatus that converts an analog input signal into a digital output signal, comprising a plurality of AD converters supplied with sampling clocks differing from each other by prescribed phase amounts, each AD converter outputting an individual signal obtained by digitizing the input signal according to the supplied sampling clock; a plurality of amplitude-dependent characteristic correcting sections that are provided to correspond to the plurality of AD converters, each amplitude-dependent characteristic correcting section generating a corrected individual signal by correcting the individual signal output by the corresponding AD converter using a correction factor corresponding to an amplitude of the individual signal; and a combining section that generates the output signal by combining a plurality of the corrected individual signals.