Adaptable RF/Analog Transmit Leakage Canceller for Simultaneous Transmit/Receive Applications

A software programmable digital domain filter supporting 250 MHz of instantaneous bandwidth (IBW) in a direct RF digital transceiver has demonstrated 25 dB of RF transmit leakage cancellation in a simultaneous transmit and receive mode at 3.0 GHz. This work advances the IBW cancellation bandwidth > 8x over current published state-of-the-art. The adaptively programmed cancellation signal is applied in the RF domain before the receive ADC increasing receiver dynamic range 25 dB while transmitting, allowing very small receive signals within the same band as the transmit band to be detected at the same time. The filter transfer function compensates for the antenna port reflection in addition to the direct leakage path across the circulator. Cancellation can be programmed to cancel transmit leakage transfer functions over the 0.8 to 11 GHz operational frequency range within the IBW. Future generations planned can support 1 GHz IBW covering 10 MHz to 20 GHz.