Self-Interference Signal Path Characterization in Full-Duplex Transceivers Using Built-in Self-Test

This paper proposes a built-in self-test (BIST) method to measure the amplitude and phase shift characteristics of the RF signal path from the transmitter to receiver in a full-duplex system. With this information, the self-interference signal (SI) may be canceled in the RF domain of a full duplex, or simultaneous transmit and receive (STAR) topology. Analysis and simulation results are presented for a 2.4GHz signal with 200MHz bandwidth, and a prototype of the BIST technique has been measured at 800MHz. The average error in phase and gain between the BIST estimated value and actual RF measured value are 0.95% and 1.43%, respectively, which supports the ability to provide 48dB of SI signal cancellation (SIC).