Shared-Path Feed-Forward Op-Amp Layout for High Loop Gain
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Solution Overview
Problem
Multi-path, multi-stage feed-forward operational amplifier circuits are inefficient in terms of size and power usage due to the large number of independent amplifiers required, which complicates chip area implementation and power operation while aiming for good noise and output-current driving performance.
Innovation Solution
The amplifier circuit design includes a plurality of amplifiers connected in partially parallel paths, with some paths sharing common amplifiers to reduce the number of independent components, allowing for efficient power allocation and improved noise and output-current driving capabilities, while maintaining high frequency loop gains with steepness increasing according to order.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-path, multi-stage feed-forward amplifier architecture is used to provide higher loop gain and steeper frequency response, then loop gain and closed-loop accuracy are improved, but the number of independent amplifiers increases leading to larger chip area and higher power consumption
Solution Approach 1:
The patent combines multiple amplification paths by having them share common amplifiers. Specifically, the first through fourth amplification paths share the fifth amplifier, and the second through fourth amplification paths share the sixth amplifier. This merging approach maintains the benefits of multi-path architecture for achieving high loop gain and steep frequency response while reducing the total number of independent amplifiers needed, thereby decreasing chip area and power consumption.
2Adaptability or versatility
If more amplifiers are added to create higher-order amplification paths for steeper loop gain, then frequency response control is improved, but chip area and power consumption increase
Solution Approach 1:
The patent implements universality by designing amplifiers that serve multiple functions across different amplification paths. The fifth amplifier serves all four amplification paths (first through fourth), and the sixth amplifier serves three amplification paths (second through fourth). This multi-functional design allows the system to achieve complex frequency response control with fewer total amplifiers, reducing chip area while maintaining adaptability.
3Reliability
If independent amplifiers are used in each amplification path to achieve good noise and output-current driving performance, then performance is improved, but power consumption and chip area increase
Solution Approach 1:
The patent merges amplification resources by having multiple amplification paths share common amplifiers (fifth and sixth amplifiers). This approach maintains the ability to achieve good noise and output-current driving performance through proper amplifier design while reducing the total number of amplifiers needed, thereby lowering overall power consumption and chip area compared to using completely independent amplifiers in each path.
Data Source
AI summary
An embodiment of an amplifier circuit includes a plurality of amplifiers connected between input and output terminals to form at least partially parallel amplification paths between the terminals. A first plurality of the amplification paths include series-connected pluralities of the amplifiers and share a common first series-connected amplifier, and a second plurality of the amplification paths have different first amplifiers. Optionally, a third plurality of the amplification paths include series-connected pluralities of the amplifiers and share a common last series-connected amplifier, and a fourth plurality of the amplification paths have different last amplifiers. Alternatively, a first plurality of the amplification paths include series-connected pluralities of the amplifiers and share a common last series-connected amplifier, and a second plurality of the amplification paths have different last amplifiers. In the alternative embodiment, optionally a third plurality of the amplification paths include series-connected pluralities of the amplifiers and share a common first series-connected amplifier, and a fourth plurality of the amplification paths have different first amplifiers.