An acoustic filter assembly for operating at a target band including multiple spaced sub-target bands. The filter assembly includes a first filter that passes a first band and a second filter that passes a second band. The first filter and the second filter have a transition band between the first band and the second band that is wider than the spacing between the sub-target bands. An interface receives a control signal that controls the transition band to be shifted between a first position and a second position, such that an upper part of a lower sub-target band is covered by the first band in the first position, and a lower part of an upper sub-target band is covered by the second band in the second position.

A device configured to support different numbers of outputs. The device includes an input port configured to receive an input signal. The device also includes a first transmission line characterized by a first characteristic impedance and coupled to a first output port. A switch is configured to either connect or disconnect the first transmission line to the input port. The device also includes a second transmission line characterized by a second characteristic impedance and coupled between the input port and a second output port. A controller is configured to activate the first switch to set a two-output mode or to deactivate the first switch to set a one-output mode. The second characteristic impedance is configured to be the same as the first characteristic impedance at the two-output mode or configured to be reduced to 1/{square root over (2)} of the first characteristic impedance at the one-output mode.

A switching circuit outputs a modulated signal. A low-pass filter circuit receives the modulated signal and applies low-pass filtering processing at a low-pass cut-off frequency to generate a demodulated signal to a load impedance. A replicating circuit receives the modulated signal and applies a replica of the low-pass filtering processing of the low-pass filter circuit to generate a reference signal. A signal processing circuit applies signal processing to the demodulated signal and the reference signal to generate at least one indicator signal which is indicative of a variation of the low-pass cut-off frequency.