Radio frequency tuner

摘要

A radio frequency tuner comprises one or more tracking filters ahead of at least one frequency changer. A controller has a filter alignment mode and a reception mode. Each filter has one or more resonant networks comprising an inductance and a switched capacitor network which is digitally controlled for selecting the network resonant frequency. In the alignment mode, the controller determines the difference between the nominal and actual capacitances of the network for achieving a known resonant frequency in order to determine a correction factor for the capacitor network. The correction factor is then used during normal reception by the tuner.