A 700–950MHz Tunable Frequency Division Duplex Transceiver Combining Passive and Active Self-Interference Cancellation

This paper presents a novel tunable FDD transceiver architecture which uses an electrical balance duplexer (EBD) to isolate Tx noise in the Rx band, and combines this with active self-interference cancellation to suppress the Tx blocker. This overcomes the limited isolation bandwidth of EBDs, shifting complexity from the RF domain to the digital baseband domain in order to provide isolation in both bands. A discrete hardware prototype has shown promising results and demonstrated the viability of this architecture, achieving 6.0–7.4 dB antenna referred noise figure in a 20 MHz downlink bandwidth, in the presence of a +27 dBm Tx blocker, across a range of duplex configurations in the 700–950 MHz range.