A Tunable Multimode Quadrature Balanced N-Path Diplexer With Nonlinear Cross-Modulation Distortion Correction

A tunable active diplexer based on quadrature balanced N-path mixers for single-antenna frequency-division duplex (FDD), half-duplex (HD), and carrier aggregation (CA) wireless is proposed. The balanced structure provides wideband TX noise cancellation in the RX band and low sensitivity to antenna VSWR variations, while sharp filtering between adjacent channels is achieved by the highly frequency-dependent input matching of the N-Path mixers. The diplexer's performance is enhanced by nonlinear digital algorithms accounting for cross-modulation distortion between the two channels and maintaining optimal performance at high TX power levels.