CIRCUIT AND METHOD FOR FEEDBACK CANCELLATION IN REPEATERS

摘要

An apparatus for repeating signals includes a receive antenna 52, 102 for receiving input signals, processing circuitry 62, 106 for processing the input signals to form repeated signals 56, and a transmit antenna 52, 54, 104 for transmitting the repeated signals 56. The processing circuitry 62, 106 includes an adaptive digital filter 72, 128 configured to generate cancellation signals that are added to the input signals to cancel unwanted feedback signals 58 from the input signals. A frequency shifting circuit 64 adds a frequency shift to the input signals, after the addition of the cancellation signals, to form repeated signals 56 that are frequency shifted from the input signals. A digital signal processor 76 is coupled to the adaptive digital filter 72, 128 for digitally adapting the filter. The digital signal processor 76 utilizes the frequency shift of the transmission signals to adapt the adaptive digital filter 72, 128.