Tunable filter arrangement, e.g. for cellular telephone, has conversion unit shifting input signal band so that effective frequency range is increased with output signal extending over larger band of frequencies than input signal

摘要

The arrangement has a filter input, at which an input signal (s1) with a frequency is applied and preferably up-converted in a mixer stage (3) by means of an oscillator signal (s2). The output of the mixer passes through a bandpass filter (2) before being down-converted in a second mixer (4) using another oscillator signal (s5) and passing through a second filter (5). The frequency conversions are arranged so that the frequency range of the output signal (s6) is larger than the range of frequencies over which the input signal extends. An independent claim is also included for a method of filtering a signal with a filter device.