Programmable Switch Banks for Charge Injection Mismatch
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Solution Overview
Problem
Electronic circuits using clock-controlled switches, such as chopper and auto-zero amplifiers, suffer from charge injection mismatch due to manufacturing variations, leading to residual differential input current and input offset voltage, which can range from 1 μV to 100 μV, affecting their performance.
Innovation Solution
The implementation of a switch bank with a selection circuit and programmable memory to observe and select switch configurations that minimize charge injection mismatch, allowing the electronic circuit to operate with reduced residual charge-injection-related errors, thereby decreasing input offset voltage and improving overall performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If clock-controlled switches are used in electronic circuits, then the circuit can perform chopping and auto-zeroing operations, but charge injection mismatch occurs due to manufacturing variations
Solution Approach 1:
The switch bank is divided into multiple individual switches that can be independently selected and configured. This segmentation allows the system to choose specific switch combinations that minimize charge injection mismatch while maintaining the ability to perform chopping and auto-zeroing operations.
Solution Approach 2:
The switch configuration is made dynamic and programmable rather than fixed. The selection circuit and programmable memory enable the switch bank to be reconfigured to optimize performance, allowing the system to adapt to minimize charge injection mismatch while maintaining operational versatility.
2Adaptability or versatility
If multiple switches are used in a switch bank, then the circuit can be configured for different operations, but charge injection mismatch increases due to manufacturing variations
Solution Approach 1:
The system incorporates a selection circuit that evaluates different switch configurations and selects the optimal combination. This feedback mechanism allows the system to identify and configure switch combinations that minimize charge injection mismatch while maintaining the desired adaptability for different operations.
Solution Approach 2:
The system changes the operational parameters by selecting different switch configurations from the switch bank. By programmatically adjusting which switches are activated and how they are connected, the system can optimize performance to minimize charge injection mismatch while maintaining operational versatility.
3Manufacturing precision
If switch configurations are selected to minimize charge injection mismatch, then input offset voltage decreases, but the device complexity increases due to selection circuit and programmable memory
Solution Approach 1:
The selection circuit and programmable memory act as intermediary components that manage the complexity of switch configuration selection. These intermediaries automate the optimization process, reducing the need for manual calibration and simplifying the overall system integration while achieving low input offset voltage.
Solution Approach 2:
The system performs self-calibration and self-configuration through the selection circuit and programmable memory. The switch bank automatically selects optimal configurations to minimize charge injection mismatch, eliminating the need for external calibration equipment or manual adjustment, thereby justifying the added complexity through automated optimization.
Data Source
AI summary
Apparatus and methods for reducing charge injection mismatch are provided herein. In certain implementations, an electronic circuit includes one or more switch banks. Each switch bank can include a selection circuit and a plurality of switches that can be controlled using one or more clock signals. The selection circuit can select a first portion of the switches for operation in a first switch group and a second portion of the switches for operation in a second switch group. During a calibration, the electronic circuit's charge injection mismatch can be directly or indirectly observed for different switch configurations of the switch banks. The electronic circuit can be programmed to operate with the selected switch configurations of the switch banks to provide the electronic circuit with small charge injection mismatch.