A baseband technique for automated LO leakage suppression achieving < −80dBm in wideband passive mixer-first receivers

A baseband technique is presented to detect and suppress LO leakage in wideband passive mixer-first receivers. Using a variable shunting resistance on the RF port, the LO leakage signal is modulated, down-converted and detected from baseband outputs. Current DACs injecting to the baseband port are up-converted and can be adjusted to cancel LO leakage. Suppression of LO on the RF port <; -80dBm is shown with a fully automated algorithm without the aid of RF spectrum monitoring.