LTE-Advanced Pro RF Front-End Implementations to Meet Emerging Carrier Aggregation and DL MIMO Requirements

RF front-end (RFFE) architectures and implementations are developing new ways to optimize LTE-Advanced PRO (Rel 13) multi-component carrier aggregation, advanced features to increase spectral efficiency such as higher order modulation and higher order MIMO, and the concurrent operation of all of these features together. In this article, we describe best practices for meeting the challenging coexistence, harmonic management, linearity, and efficiency performance related to the functional partitioning, optimized integration, and technology selection of the RFFE. Recent trends to improve radio performance are driving specific blocks (e.g., the low noise amplifier) into the RFFE, with associated architecture changes in both primary and diversity paths. Carrier aggregation features are supported in a number of different methods with different insertion loss, isolation, and noise figure trade-offs, and here we examine benefits of a new category of highly integrated diversity receive modules to enhance receiver sensitivity across all use cases. Movement toward higher order MIMO in the DL is compounding additional RF Rx path support and requirements, and cost-effective solutions for optimum performance trade-offs require a holistic and complete RF system view of both Tx and Rx in order to address these emerging requirements.