Cross-Coupled Multi-Stack Power Amplifier for Phase Alignment
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Solution Overview
Problem
Existing multi-stack power amplifiers face challenges in achieving high efficiency and stability due to circuit instability caused by feedback of unwanted signals and phase misalignment between output signals, which can lead to decreased stack efficiency.
Innovation Solution
A multi-stack power amplifier with a differential structure is designed, featuring cross-coupled amplifier elements between stacks to form virtual grounds, which cancel out unwanted signals and improve stability. Additionally, inductances in interconnections are used to compensate for phase differences between output signals, ensuring they are in phase, thus enhancing stack efficiency without requiring additional layout space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-stack power amplifier structure is used, then amplification function is achieved, but circuit instability occurs due to feedback of unwanted signals
Solution Approach 1:
The patent converts the harmful unwanted feedback signals into beneficial canceling signals by introducing cross-coupled amplifier elements. The unwanted signals that would normally cause instability are instead routed through cross-coupled paths to create cancellation effects at critical nodes, transforming the harmful feedback into a stabilizing mechanism that improves circuit reliability.
Solution Approach 2:
The patent introduces virtual ground nodes as intermediary elements between the amplifier stacks. These virtual grounds serve as mediators that receive and cancel unwanted feedback signals from multiple stacks, preventing direct feedback paths that would cause instability. The virtual grounds act as intermediate cancellation points that isolate the harmful feedback effects.
2Productivity
If amplifier elements are added to improve stack efficiency, then amplification capability increases, but phase misalignment between output signals occurs
Solution Approach 1:
The patent employs feedback mechanisms through cross-coupled amplifier elements that monitor output signals from different stacks and adjust their phases accordingly. The cross-coupled paths create feedback loops that automatically compensate for phase misalignments, ensuring that output signals from multiple stacks remain synchronized and in-phase, thereby maintaining manufacturing precision in phase alignment.
Solution Approach 2:
The patent changes the electrical parameters (phase and amplitude) of signals by routing them through cross-coupled amplifier elements. By adjusting the number of cross-coupled elements and their coupling strengths, the patent dynamically modifies signal parameters to compensate for phase misalignment, transforming the phase relationship between outputs to achieve proper synchronization.
3Reliability
If cross-coupled amplifier elements are added to cancel unwanted signals, then circuit stability improves, but layout space increases
Solution Approach 1:
The patent merges the functions of multiple amplifier elements into a compact cross-coupled configuration. Instead of adding separate cancellation circuits that would occupy additional space, the patent combines the amplification and cancellation functions within the same cross-coupled amplifier elements, allowing them to serve dual purposes and reduce overall layout space while maintaining circuit stability.
Solution Approach 2:
The patent utilizes vertical stacking and multi-layer interconnections to accommodate cross-coupled amplifier elements in the third dimension rather than spreading them out in the planar layout. By transitioning from a two-dimensional layout to a three-dimensional configuration with vertical interconnections, the patent reduces the footprint area while maintaining the necessary cross-coupling paths for stability.
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 proposed solution effectively reduces circuit instability and improves stack efficiency by canceling out unwanted signals and compensating for phase misalignments, thereby enhancing the overall performance of the power amplifier without increasing the layout space.
Implementation Method 1
The first interconnection includes an inductance configured to compensate for a phase difference between an output signal of the first amplifier element and an output signal of the third amplifier element, and the second interconnection includes an inductance configured to compensate for a phase difference between an output signal of the second amplifier element and an output signal of the fourth amplifier element.
Implementation Method 2
A first virtual ground, in which the first coupling signal and the second coupling signal cancel each other out, may be formed in a region through which a ground of the first amplifier element and the ground of the fourth amplifier element are connected to each other. A second virtual ground, in which the third coupling signal and the fourth coupling signal cancel each other out, may be formed in a region through which a ground of the second amplifier element and the ground of the third amplifier element are connected to each other.
Data Source
AI summary
A multi-stack power amplifier having a differential structure includes a first stack including a first amplifier element, configured to amplify a first signal having a first phase, and a second amplifier element configured to amplify a second signal having a second phase opposite to the first phase; and a second stack including a third amplifier element, connected to an output terminal of the first amplifier element through a first interconnection, and a fourth amplifier element connected to an output terminal of the second amplifier element through a second interconnection intersecting the first interconnection.