Adaptive filtering for canceling distortion in radio frequency signals

摘要

Adaptive filtering is used to substantially cancel distortion in radio frequency (RF) signals. Such adaptive filtering can be used in an RF transmitting module to pre-compensate an RF signal with compensation (inverse) distortion to cancel inherent transmission path distortion from the RF signal. Adaptive filtering can also be used in a multi-carrier RF receiving module to cancel from a given carrier signal distortion due to cross talk from adjacent carrier signals. Adaptive filtering in an RF transceiver can be used to cancel from a received RF signal distortion arising from leakage of a transmit signal into the receive path.

主权项

1. A radio frequency (RF) transmitting module comprising:
a transmission path that imparts inherent path distortion to signals; a model of said transmission path, said model comprising an input and an output, said model configured to impart to a communications signal at said input modeled distortion that corresponds to said inherent path distortion and thereby provide at said output a model-distorted version of said communications signal; a filter comprising a control input, a signal input connected to said input of said model and a signal output connected to said transmission path, said adaptive filter configured to filter, in accordance with a variable filtering characteristic, said communications signal to impart compensation distortion to said communications signal and thereby provide at said signal output a compensated version of said communications signal; an adaptive module comprising only two inputs, one input connected to said output of said model, and an other input connected to the output of the filter, and an output connected to said control input of said filter, said adaptive module configured to vary said variable filtering characteristic in accordance with said model-distorted version of said communications signal; and an electronic controller configured to: identify a current operating condition of said transmission path, and select one of a plurality of different models as said model that corresponds to said identified current operating condition of said transmission path, wherein no input of said filter is connected to said transmission path, and no input of said model of said transmission path is connected to said transmission path.