Comparator Offset Correction with Holding Capacitors for Low-Power ADCs
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Solution Overview
Problem
Comparator circuitry in analogue-to-digital converters (ADCs) faces accuracy issues due to mismatches between components, leading to offset errors that affect comparison results, particularly at increasing speeds and miniaturization of semiconductor devices.
Innovation Solution
A comparator with controllable offset-correction components, including holding and supply capacitors, and switching circuitry, which adjusts offset-correction signals through charging and charge-sharing operations, allowing for precise calibration and low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset correction is implemented using traditional methods, then comparison accuracy is improved, but power consumption increases and calibration frequency requirements increase
Solution Approach 1:
The patent implements dynamic offset correction by making the offset correction signal adjustable and controllable. The system dynamically adapts the offset correction amount based on detected comparison results, allowing the correction mechanism to activate only when needed rather than operating continuously, thus reducing power consumption while maintaining accuracy.
Solution Approach 2:
The patent employs feedback mechanisms where comparison results are used to detect offset conditions and trigger corrective actions. The system monitors its own performance and adjusts offset correction signals based on detected errors, creating a closed-loop control system that improves accuracy only when deviations are detected, thereby reducing unnecessary power consumption.
2Measurement precision
If offset correction is implemented using traditional methods, then comparison accuracy is improved, but calibration frequency requirements increase
Solution Approach 1:
The system uses feedback from comparison results to detect when offset correction is needed. By monitoring comparison outcomes and identifying patterns indicating offset drift, the system triggers calibration only when necessary rather than performing frequent periodic calibration, thus reducing time loss while maintaining accuracy.
Solution Approach 2:
The patent implements self-service offset correction where the system automatically detects and corrects its own offset errors using its comparison results. The comparator monitors its own performance and initiates correction procedures autonomously, reducing the need for external calibration interventions and minimizing calibration frequency requirements.
3Area of moving object
If component miniaturization is pursued to increase integration, then device density is improved, but offset errors increase due to mismatch
Solution Approach 1:
The patent applies local quality correction by implementing offset correction specifically targeted at the comparator circuit where mismatches occur. Rather than attempting to prevent mismatches through uniform miniaturization, the system applies localized correction signals to the affected comparator components, allowing miniaturization to proceed while compensating for local variations in component characteristics.
Solution Approach 2:
The system changes operational parameters by adjusting offset correction signals dynamically. By modifying the offset correction amounts based on detected comparison results, the system compensates for parameter variations caused by miniaturization-induced mismatches, maintaining measurement precision despite reduced component sizes and increased integration density.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high-speed, low-offset comparisons with high resolution and low current consumption, allowing for accurate and efficient offset correction, reducing the frequency of calibration needs.
Implementation Method 1
the at least one offset-correction circuit comprises a holding capacitor, a supply capacitor and switching circuitry, the holding capacitor connected to the input terminal of the offset-correction component concerned and configured to provide the offset-correction signal at the input terminal concerned based on charge stored on that holding capacitor
Implementation Method 2
the switching circuitry is configured, in a charging operation, to connect the supply capacitor to a charging-operation voltage supply to store charge on that capacitor
Implementation Method 3
in a charge-sharing operation, to disconnect the supply capacitor from the charging-operation voltage supply and connect it to the holding capacitor to adjust the charge stored on the holding capacitor (through charge sharing between the supply and holding capacitors)
Data Source
AI summary
A comparator including: first and second input transistors connected to control signals at first and second nodes of the comparator; latch circuitry; at least one controllable offset-correction component having an input terminal and connected to control the signal at one of the first and second nodes based on an offset-correction signal provided at its input terminal; for each controllable offset-correction component, an offset correction circuit configured to provide the offset-correction signal provided at its input terminal; and control circuitry. The control circuitry controls the at least one offset-correction circuit to: control an amount by which the offset-correction signal is adjusted; and/or in a bypass operation, connect the input terminal of the at least one controllable offset-correction component to a bypass-operation reference voltage supply; and/or in a maintenance operation, control the charging-operation voltage supply and/or the bypass-operation voltage supply to control leakage of the charge stored on the holding capacitor.