Operational Amplifier Hysteresis Comparator Without Positive Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hysteresis comparators with positive feedback introduce instability and occupy large layout areas, while traditional designs struggle to efficiently generate hysteresis voltage with optimal output characteristics.
Innovation Solution
An operational amplifier-based hysteresis comparator that adjusts the number of input sub-branches in its input stage to change the effective width-to-length ratio, providing adjustable hysteresis windows and reducing instability by using a smaller number of transistors, thereby minimizing layout area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If positive feedback is introduced to create hysteresis characteristic, then anti-interference ability is improved, but circuit stability deteriorates and layout area increases
Solution Approach 1:
The patent extracts the hysteresis function from the traditional positive feedback mechanism and implements it through a dedicated hysteresis voltage generation circuit. This separates the hysteresis generation function from the main comparison operation, allowing the comparator to achieve anti-interference capability without the instability associated with positive feedback in the signal path.
Solution Approach 2:
The patent introduces an intermediary hysteresis voltage generation circuit that produces reference voltages with built-in hysteresis characteristics. This intermediary circuit acts as a mediator between the input signal and the comparator, providing the desired hysteresis effect without requiring direct positive feedback connection that would cause instability.
2Object-affected harmful factors
If traditional hysteresis comparator design with positive feedback is used, then hysteresis characteristic is achieved, but layout area becomes overlarge
Solution Approach 1:
The patent segments the comparator into distinct functional modules: input stage, hysteresis voltage generation circuit, and output stage. This segmentation allows each module to be optimized independently, with the hysteresis voltage generation circuit using a compact design that significantly reduces the overall layout area compared to traditional positive feedback implementations.
Solution Approach 2:
The patent changes the design parameters of the hysteresis generation mechanism by using configurable transistor branches with selectable width-to-length ratios. This allows precise control of hysteresis voltage while maintaining a compact circuit structure, reducing layout area while preserving the essential hysteresis characteristic.
3Adaptability or versatility
If multiple input sub-branches are connected in parallel to adjust width-to-length ratio, then hysteresis window is provided, but device complexity increases
Solution Approach 1:
The patent implements dynamic configurability in the input stage by using control signals to selectively enable or disable specific transistor branches. This allows the width-to-length ratio to be dynamically adjusted without permanently connecting multiple complex branches, reducing device complexity while maintaining adaptability for different hysteresis window requirements.
Solution Approach 2:
The patent designs the input stage with universal transistor branches that can serve multiple functions depending on configuration. The same physical transistors can be used for different hysteresis window adjustments by changing which branches are active, rather than requiring dedicated branches for each configuration, thereby reducing overall device complexity.
Data Source
AI summary
An operational amplifier-based hysteresis comparator and a chip are provided. The hysteresis comparator includes: an input stage and an amplification stage. The input stage includes: a first input branch and a second input branch, where the first input branch generates a first current based on the first voltage, and the second input branch generates a second current based on the second voltage. The first current is connected with a first input terminal of the amplification stage, and the second current is connected with a second input terminal of the amplification stage. An output terminal of the amplification stage outputs a first level when the first current is greater than the second current, and outputs a second level when the first current is less than the second current. The present disclosure changes the hysteresis voltage generation mode, thereby reducing the instability caused by positive feedback.