A 12 dBm B1dB N-Path Notch Filter for Transmitter Leakage Suppression in Wideband Receiver

This paper proposes an N-path notch filter while offering high blocker power handling for co-address transmitter (TX) leakage suppression in a wideband receiver. The filter includes an impedance flip-flop over an adjustable transmission line in a block band, achieving a 12.3 to 13.6 dBm blocker 1 dB compression point (B1dB) and a 12.8 to 14 dBm 1 dB compression point (P1dB) in a 130 nm CMOS SOI process. This design effectively suppresses broadband interference in the receiving system and improves the dynamic range and linearity of the receiver (RX) channel. The filter consumes 186 to 242 mW in the 0.3 GHz to 0.6 GHz band and has an active chip area of 0.21 mm2, providing maximum rejection >25 dB, with a passband third-order input intercept point (IIP3) of 22 to 25.2 dBm. The design of the adjustable transmission line structure is analyzed to reduce the insertion loss in terms of impedance and to achieve a 1.7 to 2 dB insertion loss shortfall over the RF tuning range.