A Full-Duplex Rake Receiver Using RF Code-Domain Signal Processing for Multipath Environments

This article presents a full-duplex (FD) rake receiver (RX) that uses the orthogonality properties of pseudo-noise (PN) codes to reject transmitter (TX) self-interference (SI) in the RF domain, allowing simultaneous transmit and receive (STAR) operation in the same frequency channel. The rake RX also exploits multipath propagation in wireless channels and PN code orthogonality to gather signals across multipath components to increase the signal-to-noise ratio (SNR) while avoiding the fading effects of multipath channels. The rake RX shares a low-noise amplifier (LNA) between the three rake fingers and a high-linearity baseband (BB) section with the second-order filtering to improve the rejection with low power consumption. Measurements indicate that TX SI rejection is 41.2 dB in the RF domain with 9-dB SNR improvement in a multipath channel. The rake RX is implemented in a 45-nm RFSOI CMOS process and occupies an active area of 1.6 mm2 while consuming 45.8 mW per finger, including clock power consumption.