Residue Generator Charge Injection Cancellation in Pipelined ADCs
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Solution Overview
Problem
Pipelined analog-to-digital converter systems face accuracy degradation due to spurious charge injection in conventional residue generators, which cannot be corrected and thus irreversibly degrade system performance.
Innovation Solution
The implementation of residue generator embodiments that reduce spurious charges by providing opposing reduction charges to the reference source, utilizing a charge injector with replica capacitors and switches to mimic the sample capacitors and switches, thereby enhancing system accuracy and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional residue generators are used in pipelined converter stages, then the system can operate at high sample rates, but spurious charge injection degrades conversion accuracy
Solution Approach 1:
The patent applies preliminary anti-action by injecting reduction charges into the reference source before the spurious charges are generated by the main switch network. The charge injector circuit, controlled by a reduction clock signal, proactively counteracts the charge injection effect, preventing accuracy degradation before it occurs during the conversion process
Solution Approach 2:
The patent introduces a charge injector circuit as an intermediary component between the main switch network and the reference source. This intermediary circuit, consisting of replica capacitors and injection switches, mediates the charge interaction by providing reduction charges that offset the spurious charges, thereby protecting the reference source from direct charge injection effects
2Productivity
If spurious charges are injected into the reference source during conversion operations, then switching operations can be performed, but the accuracy of the residue signal is irreversibly degraded
Solution Approach 1:
The patent implements feedback by using replica capacitors that mirror the charging behavior of the main switch network. The charge injector circuit monitors and replicates the charge injection pattern, then feeds back reduction charges through the injection switches to counteract the spurious charges, creating a closed-loop correction mechanism that maintains residue signal accuracy
Solution Approach 2:
The patent uses copying by creating replica capacitors that are identical copies of the main switch network capacitors. These replica capacitors replicate the charging and discharging behavior, allowing the charge injector to generate accurate reduction charges that match the spurious charge pattern, thereby enabling precise cancellation of the harmful charge injection effects
Data Source
AI summary
Pipelined converter systems include a plurality of converter stages in which some stages generate and pass a residue signal to a succeeding stage for further conversion. The generation of the residue signal can inject spurious charges into a reference source that is used in the generation. The spurious charges reduce the accuracy of the residue signal and the accuracy of the system. Residue generator embodiments are thereby formed to provide reduction charges to the reference source that are arranged to oppose and reduce the spurious charges. This reduction of spurious charges significantly enhances system accuracy and linearity.