LNA Protection Circuit for Co-Located Radio Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-radio systems with co-located radios, the proximity and low isolation between radios can cause the low noise amplifier (LNA) of a receiver to be saturated or desensed by an aggressor signal, leading to degradation of the desired signal and bit errors.
Innovation Solution
An LNA protection circuit is activated based on the state of both the victim and aggressor radios, attenuating both signals when the aggressor signal exceeds a threshold, and deactivated when the desired signal is complete, with an automatic gain controller maintaining consistent gain during reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If co-located radios are placed in close proximity to reduce system size, then device compactness is improved, but interference between radios increases causing LNA saturation and signal degradation
Solution Approach 1:
An LNA protection circuit is introduced as an intermediary component between the aggressor radio and the victim radio's LNA. This protection circuit selectively attenuates the aggressor signal when it exceeds a threshold level, preventing LNA saturation while allowing normal signal passage. The protection circuit acts as a mediator that resolves the interference problem without requiring physical separation of the radios.
2Reliability
If LNA gain is reduced to prevent saturation from aggressor signal, then LNA saturation is avoided, but sensitivity to desired signal decreases
Solution Approach 1:
The LNA protection circuit dynamically adjusts its attenuation level based on the strength of the aggressor signal. When the aggressor signal exceeds a threshold, the protection circuit activates and attenuates the signal by a controlled amount (e.g., 20-25 dB). This dynamic adjustment prevents LNA saturation while minimizing impact on desired signal sensitivity, as the attenuation is only applied when necessary and at a level that maintains acceptable signal quality.
3Object-affected harmful factors
If LNA protection circuit is activated to attenuate aggressor signal, then interference is reduced, but desired signal power is also reduced
Solution Approach 1:
The LNA protection circuit employs feedback mechanisms to monitor both the aggressor signal level and the desired signal characteristics. Based on this feedback, the protection circuit intelligently adjusts its attenuation level and activation state. When the aggressor signal exceeds the threshold, the protection circuit activates with a controlled attenuation level that balances interference reduction with desired signal preservation. The feedback ensures that attenuation is applied selectively rather than continuously, minimizing impact on desired signal power.
Data Source
AI summary
An indication is received that an aggressor radio co-located with a victim radio is to transmit an aggressor signal. A low noise amplifier (LNA) protection circuit is activated in response to a desired signal being received and based on the indication. The LNA protection circuit is deactivated in response to the receipt of the desired signal being completed.