Matrix Distributed Amplifier With Active Termination for Low Noise
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Solution Overview
Problem
Traditional distributed amplifiers face challenges in achieving high gain-bandwidth product with low noise figure and maintaining linearity, particularly due to phase velocity variations and adverse coupling interactions between stages, which degrade noise performance and linearity.
Innovation Solution
A matrix distributed amplifier design that replaces noisy drain terminations with an amplifier termination stage, employing a 2×N matrix configuration with input and output transmission lines and intermediate amplifiers, and using cascode transconductor cells and feedback amplifiers to optimize broadband noise and linearity performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional distributed amplifiers use multiple transconductance elements coupled together to increase gain-bandwidth product, then the gain-bandwidth product is improved, but phase velocity variations and distortions along the output line degrade linearity and efficiency
Solution Approach 1:
The amplifier is divided into multiple discrete transconductance elements (first plurality and second plurality of amplifiers) distributed along the transmission lines. Each element processes a portion of the signal, allowing the system to achieve high gain-bandwidth product while maintaining linearity through distributed processing rather than a single large amplifier stage.
Solution Approach 2:
The patent introduces an intermediate transmission line that couples the first plurality of amplifiers to the second plurality of amplifiers. This intermediate structure acts as a mediator that manages signal distribution and timing, reducing phase velocity variations and their harmful effects on linearity while preserving the high gain-bandwidth product.
2Power
If cascaded two stage amplifier is used to achieve sufficient gain, then the desired gain is achieved, but adverse coupling interaction between stages degrades noise figure and linearity
Solution Approach 1:
The patent merges two distributed amplifier stages into a unified matrix structure where the first and second pluralities of amplifiers operate together in a coordinated fashion. This integration reduces adverse coupling interactions between stages while achieving the desired gain, and the intermediate transmission line further isolates the stages to prevent noise figure degradation.
Solution Approach 2:
The patent employs feedback amplifiers that receive signals from the transmission lines and feed them back to previous stages. This feedback mechanism compensates for distortions and reduces the impact of adverse coupling interactions, maintaining both the desired gain and acceptable noise figure performance.
3Power
If cascaded two stage amplifier is used to achieve sufficient gain, then the desired gain is achieved, but higher gain and signal through combined stages requires output stage to have better linearity than overall desired cascaded linearity
Solution Approach 1:
The amplifier is segmented into multiple distributed elements rather than using a single high-gain stage. This segmentation distributes the gain across many smaller amplification steps, reducing the linearity burden on any single output stage while achieving the overall desired gain through cumulative amplification.
Solution Approach 2:
The patent transitions from a conventional single-stage or cascaded two-stage architecture to a two-dimensional matrix structure with multiple amplifiers arranged in parallel and series combinations. This dimensional change allows gain to be achieved through multiple pathways, distributing the linearity requirements across the entire matrix rather than concentrating them in the output stage.
4Reliability
If amplifier termination stage replaces noisy drain terminations, then noise figure is reduced, but device complexity increases
Solution Approach 1:
The amplifier termination stage uses active amplifier elements rather than passive resistive terminations. These active elements provide both termination and signal amplification functions, reducing noise figure while the distributed nature of the termination amplifiers integrates them into the existing amplifier structure, mitigating the increase in device complexity.
Data Source
AI summary
Disclosed is a matrix distributed amplifier (DA) having an input transmission line, an intermediate transmission line, and an output transmission line. A first plurality of amplifiers has inputs coupled to and spaced along the input transmission line and has outputs coupled to and spaced along the intermediate transmission line. A second plurality of amplifiers has inputs coupled to and spaced along the intermediate transmission line and has outputs coupled to and spaced along the output transmission line. A termination amplifier has an input coupled to the input transmission line and an output coupled to the intermediate transmission line. In at least one embodiment, a second termination amplifier has an input coupled to the intermediate transmission line and an output coupled to the output transmission line.