RF filter arrangement with image trap

摘要

A tuner includes a tunable filter (907-2) for selecting a desired RF signal in response to a tuning control signal and a tunable image trap (907-3) for rejecting the undesired image signal corresponding to the desired RF signal responsive to the tuning control signal coupled in cascade between an RF amplifier (905) and a mixer (909). The tunable trap (907-3) also serves as an impedance transformation element between the tunable filter (907-2) and said mixer (909). The arrangement is particularly useful in a tuner in which the frequency range of the local oscillator signal is below the frequency range of the received RF signals.