Multi-Input Variable-Gain Amplifier With Low-Loss Bypass Modes
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Solution Overview
Problem
Wireless communication devices face challenges in providing efficient amplification of radio-frequency signals with multiple gain modes while maintaining linearity and reducing noise, particularly in scenarios where different antennas receive signals with varying characteristics.
Innovation Solution
A variable-gain signal amplifier with a degeneration switching block and medium gain mode feedback block, which provides tailored impedances and bypass paths to achieve improved linearity and low-loss direct bypass modes across various gain levels, allowing for independent amplification of signals from multiple input ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a variable-gain amplifier provides multiple gain modes with high amplification, then the amplification capability is improved, but the linearity deteriorates
Solution Approach 1:
The amplifier is divided into multiple independent gain stages (first gain stage, second gain stage, third gain stage) that can be selectively activated. Each stage provides a portion of the total gain, allowing the system to achieve high overall gain while maintaining linearity by distributing the amplification burden across multiple linear stages rather than overdriving a single stage.
Solution Approach 2:
The amplifier dynamically switches between different gain modes by activating or deactivating specific gain stages based on the required amplification level. This dynamic configuration allows the system to adapt its gain structure to maintain optimal linearity for each operating condition, rather than compromising linearity across all gain settings.
2Loss of energy
If a bypass path is provided for low gain modes, then the loss is reduced, but the device complexity increases
Solution Approach 1:
The amplifier structure is segmented into multiple gain stages with individual control, allowing selective activation of only the necessary stages for each operating condition. For low gain modes, only the essential stages are activated and a bypass path is enabled, reducing the number of active components in the signal path and minimizing signal loss while maintaining a manageable overall structure.
Solution Approach 2:
The bypass path serves multiple functions: it provides a low-loss signal path for low gain modes, and can be combined with active gain stages to achieve medium gain modes. This multi-functionality reduces the need for completely separate amplifier paths for different gain requirements, thereby reducing overall device complexity.
Data Source
AI summary
Described herein are variable-gain amplifier configurations that include a multi-input gain stage, a cascode buffer, and a bypass block. Degeneration switching blocks can be used for the entire multi-input gain stage or for individual input nodes of the multi-input gain stage. This advantageously reduces or eliminates performance penalties in one or more gain modes. The variable impedances can be configured to improve linearity of the amplification process in targeted gain modes. The variable gain amplifier can be configured to provide a low-loss bypass mode in a low gain mode to improve signal quality.