Patent ID: 8862088

Claim:
An apparatus comprising an amplifier with a feedback loop circuitry, wherein the feedback loop circuitry comprises: a first frequency converter circuitry configured to frequency-convert a signal input to the feedback loop circuitry from a first frequency to a second frequency by using a first local oscillator signal; a filter circuitry configured to modify the frequency-converted signal on the second frequency; and a second frequency converter circuitry configured to frequency-convert the modified signal from the second frequency back to the first frequency by using a second local oscillator signal and to output the frequency-converted and modified signal to be applied to an input of the amplifier, wherein the feedback loop circuitry implements a band-stop filter having an adjustable stopband causing the amplifier to have an adjustable band-pass response, and wherein a passband of the amplifier is changed from one operating frequency to another operating frequency by changing frequency conversion parameters of the first frequency converter circuitry and the second frequency converter circuitry.