Operational Amplifier Layout With Virtual Output Node Feedback
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Solution Overview
Problem
Conventional integrated circuit layouts for operational amplifiers suffer from output voltage offset due to resistance in routing paths, leading to different output characteristics at output pads, which affects display performance.
Innovation Solution
The method involves constructing an output path connecting the output terminal of the operational amplifier to an output pad with a minimum distance, and a feedback path connecting an input terminal to an element near the output pad, where the distance between the element and the output pad is less than a tenth of the feedback path length, minimizing resistance and voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the output path is made long to reach the output pad, then the output voltage offset increases due to resistance, but the routing can accommodate layout constraints
Solution Approach 1:
The patent introduces a virtual output node as an intermediate connection point between the physical output terminal and the output pad. This virtual node allows the feedback path to be routed through a different dimensional path (through the virtual node) rather than directly along the physical output path, effectively decoupling the feedback signal from the resistive voltage drop in the physical routing.
Solution Approach 2:
The virtual output node serves as an intermediary element that mediates between the output terminal and the output pad. It provides a reference point for the feedback path without being subject to the same resistive effects as the physical output path, thus eliminating the output voltage offset while maintaining proper feedback functionality.
2Device complexity
If the feedback path is routed through the output path, then the feedback signal is affected by resistance and voltage drop, but the routing structure is simplified
Solution Approach 1:
The patent segments the feedback path into two distinct parts: a first routing path from the output terminal to the virtual output node, and a second routing path from the virtual output node to the inverting input terminal. This segmentation allows the feedback signal to be taken from a point (virtual output node) that is electrically close to the output terminal, minimizing the effect of resistance and voltage drop while maintaining a manageable routing structure.
Solution Approach 2:
The virtual output node acts as an intermediary that enables the feedback path to bypass the resistive effects of the physical output path. By routing the feedback signal through this virtual node rather than along the entire physical output path to the output pad, the patent eliminates voltage drop effects while keeping the routing structure organized and manageable.
3Adaptability or versatility
If multiple output paths have different lengths, then output characteristics vary across pads, but flexible routing is achieved
Solution Approach 1:
The patent introduces a virtual output node that serves as a common reference point for all feedback paths, regardless of the physical distance to different output pads. This virtual node creates a unified electrical reference that decouples the feedback signal quality from the physical routing length, allowing different output paths to have different lengths while maintaining consistent output characteristics across all pads.
Solution Approach 2:
By using the virtual output node as the reference point for the feedback path, the patent creates an equipotential reference that is electrically close to the output terminal for all channels. This ensures that all output paths, regardless of their physical length to the output pad, have equivalent feedback conditions, thereby maintaining consistent output characteristics across multiple pads.
Data Source
AI summary
A method for implementing a layout of an integrated circuit containing an OP (operational amplifier) is disclosed. The method includes constructing an output path connecting an output terminal of the OP to an output pad of the OP; and constructing a feedback path connecting an input terminal of the OP to an element of the OP, the element lying in an area covering the output pad, in which a minimum distance between the element and the output pad is less than a tenth of length of the feedback path. The present invention also provides an integrated circuit device produced through the method.