Zeroth-Order Optimization for Self-Interference Cancellation in STAR Front-End

A balanced amplifier with adaptive self-interference (SI) cancellation architecture is presented with an optimized correction approach that can correct for real-time changes in dynamic loading conditions. Zeroth-order gradient descent methods are applied to the system to minimize the SI power at the receive port. The optimization algorithm has been demonstrated experimentally to reduce self-interference by approximately 28 dB in different constant-impedance scenarios and to improve self-interference in dynamic loading environments by upwards of 25.5 dB.