Signal Receiving Circuit With Switchable RF Gain Under Interference
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Solution Overview
Problem
Wireless communication systems face challenges in maintaining sensitivity while improving linearity of low noise amplifiers, especially when interference signals overlap with received signals, leading to increased noise figure and reduced sensitivity.
Innovation Solution
A signal receiving circuit with a switch circuit that determines whether to amplify a radio frequency signal, using a first amplifier, a second amplifier, and a mixer to adjust gain and prevent non-linear amplification, allowing for better flexibility in receiving different signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the gain of the low noise amplifier is decreased to improve linearity, then the linearity of the receiving system is increased, but the noise figure is also increased which affects the sensitivity of the receiving system
Solution Approach 1:
The patent implements dynamic gain control by switching between a first low noise amplifier and a second amplifier based on signal strength detection. When the input signal is weak, the first LNA with higher gain is selected to maintain sensitivity. When the input signal is strong, the second amplifier with lower gain is selected to improve linearity. This dynamic adaptation resolves the contradiction between linearity and sensitivity.
Solution Approach 2:
The patent changes the gain parameter of the amplification stage by selecting different amplifiers with different gain characteristics. The system detects the input signal strength and accordingly selects the appropriate amplifier gain setting, thereby adjusting the operating point to optimize both linearity and sensitivity under different signal conditions.
2Measurement precision
If the gain of the low noise amplifier is increased to maintain sensitivity, then the sensitivity of the receiving system is improved, but the linearity is degraded making the signal prone to non-linear distortion
Solution Approach 1:
The system dynamically adjusts the amplifier selection based on real-time signal strength detection. When the signal is weak, the first LNA with higher gain is activated to ensure sufficient sensitivity. When the signal becomes strong, the system switches to the second amplifier with lower gain to prevent non-linear distortion, thus dynamically resolving the linearity-sensitivity tradeoff.
Solution Approach 2:
The patent employs a feedback mechanism where the detected signal strength information is used to control the switch circuit selection. The detection unit monitors the input signal level and provides feedback to the switch circuit, which then selects the appropriate amplifier. This closed-loop control ensures optimal linearity and sensitivity by continuously adapting to signal conditions.
3Device complexity
If a single low noise amplifier is used to simplify the device structure, then the device complexity is reduced, but the system cannot adapt to different signal conditions leading to performance degradation
Solution Approach 1:
The patent segments the amplification function into multiple independent amplifier units with different gain characteristics. Instead of using a single amplifier, the system divides the amplification task across a first low noise amplifier and a second amplifier, each optimized for different signal conditions. This segmentation enables the system to adapt to varying signal strengths while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The amplifier selection circuit serves multiple functions: it detects signal strength, determines the appropriate amplifier configuration, and switches between different amplifier modes. This multi-functional design allows the system to handle both weak and strong signals effectively without requiring completely separate receiver paths, thus maintaining reasonable device complexity while achieving high adaptability.
Data Source
AI summary
A signal receiving circuit includes a first amplifier, a switch circuit, a second amplifier and a mixer. The first amplifier is configured to amplify a radio frequency (RF) signal to generate a first amplified RF signal. The switch circuit is configured to receive the first amplified RF signal. The second amplifier is configured to receive and amplify the first amplified RF signal to generate a second amplified RF signal. The mixer is configured to modulate one of the first amplified RF signal and the second amplified RF signal to generate a mixed signal, wherein the switch circuit is configured to determine whether the first amplified RF signal is amplified by the second amplifier.