Split LNA Receiver Topology for Carrier Aggregation Isolation
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Solution Overview
Problem
Current Radio Frequency Front End (RFFE) circuits with low noise amplifiers face challenges in achieving high isolation and low losses while handling broad frequency ranges, particularly in receiver systems that require intraband and interband carrier aggregation, leading to reduced sensitivity and increased noise figure.
Innovation Solution
A flexible receiver front end circuit design incorporating multiple low noise amplifiers (LNAs) with cascode amplifier stages and a split LNA configuration, allowing for efficient amplification and processing of single-band and multi-band RF signals with high isolation and low noise, while minimizing area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single LNA is used to amplify signals over a broad frequency band, then the frequency range coverage is improved, but the isolation between different signal paths deteriorates and noise figure increases
Solution Approach 1:
The LNA is divided into multiple independent amplifier stages, each optimized for specific frequency bands. The first LNA amplifies first frequency band signals while the second LNA amplifies second frequency band signals, providing high isolation between bands through physical separation and independent tuning of each stage.
Solution Approach 2:
The patent introduces a third dimension to the signal path by adding a second LNA that processes signals in a different frequency band simultaneously. This dimensional expansion allows the system to handle intraband and interband carrier aggregation without compromising isolation, as each LNA operates in its own frequency domain.
2Reliability
If multiple LNAs are used to handle different frequency bands, then the isolation and noise figure are improved, but the device complexity and area increase
Solution Approach 1:
Each LNA stage is designed with universal functionality to handle multiple signal types including non-carrier aggregated signals, intraband carrier aggregated signals, and interband carrier aggregated signals. The LNAs can be selectively activated based on the received signal type, providing multi-functionality without requiring separate dedicated amplifiers for each signal category.
Solution Approach 2:
The system dynamically selects which LNA stage(s) to activate based on the detected signal type and frequency band. Control circuitry enables or disables specific LNA stages to match the incoming signal characteristics, optimizing performance while minimizing the active complexity at any given moment.
3Adaptability or versatility
If passive splitters are used to separate carrier aggregated signals, then the signal routing flexibility is improved, but the insertion loss increases
Solution Approach 1:
Active LNA stages serve as intermediary components between the antenna and the signal processing circuits. Instead of using passive splitters that divide and lose signal power, the active LNAs amplify the signals before they reach the splitting network, compensating for insertion losses and providing sufficient signal strength to multiple downstream circuits simultaneously.
Data Source
AI summary
A receiver topology for supporting various combinations of interband carrier aggregation (CA) signals, intraband non-contiguous CA and non-CA signals having different combinations of signals aggregated therein.