An amplifier circuitry having adjustable parameters is presented. The present amplifier circuitry includes a feed-back loop, wherein the feedback loop converts (26) a signal to another frequency, filters (20) the signal in the other frequency, and restores (24) the filtered signal back to the original frequency for inputting the signal to an input of the amplifier (22). The feed-back loop implements a band-stop filter (20) having an adjustable stopband causing the amplifier circuitry to have an adjustable band-pass response. A passband of the amplifier circuitry is changed from one operating frequency to another operating frequency by changing frequency conversion parameters of the feedback loop.