Cartesian RF Feedback Loop with Parallel Paths for Multi-Carrier Linearization

The feedback loop is segmented into multiple parallel paths (main path and auxiliary path), each with its own power amplifier. The main path handles lower frequencies with a main RF power amplifier, while the auxiliary path handles higher frequencies with an auxiliary RF power amplifier. This segmentation allows each amplifier to be optimized for specific frequency ranges, achieving adequate linearization performance across wide carrier ranges while using fewer total amplifiers than a single-carrier-per-amplifier approach.

The patent introduces a frequency-dimension differentiation by splitting the feedback loop into parallel paths that handle different frequency ranges. The main path processes lower frequency signals while the auxiliary path processes higher frequency signals. This dimensional separation in the frequency domain enables a single multi-carrier RF power amplifier to achieve sufficient linearization performance across wide carrier bandwidths.

The loop filter response is segmented into different orders for different paths. The main path uses a higher order loop filter (e.g., second order) to achieve strong linearization performance for lower frequency signals, while the auxiliary path uses a lower order loop filter (e.g., first order) to maintain stability for higher frequency signals. This segmentation allows the system to benefit from high-order filtering where it provides value while avoiding instability issues in other frequency ranges.

Different loop filter orders are applied locally to different frequency paths based on their specific requirements. The main path, handling lower frequencies, receives higher order filtering for maximum linearization benefit. The auxiliary path, handling higher frequencies, receives lower order filtering to prevent instability. This local optimization of filter order matches the quality of filtering to the specific needs of each frequency path.