High-Power Tunable FDD Front-End Employing a Balanced CMOS N-Path Receiver and Evanescent-Mode Cavity Filters

A single-antenna, frequency-tunable FDD front-end supporting simultaneous transmit (TX) and receive (RX) operation with high power handling capabilities and low TX and RX losses is presented. The system comprises a balanced CMOS N-path receiver in series with tunable evanescent-mode filters, and leverages frequency-selective reflectivity and matching for quadrature signal construction and self-interference cancellation at corresponding ports of interest. A measured 65 nm CMOS receiver prototype with manufactured cavity filters demonstrated 38 dBm blocker tolerance (B1dB) around 1 GHz at 100 MHz TX−RX spacing with no RX EVM degradation, < 0.4 dB TX insertion loss, and 3.5−4.5 dB RX NF over 0.9−1.8 GHz tunable frequency range.