A cascade-connected transistor includes a common-source transistor which receives an input signal, and a common-gate transistor which is connected to a drain terminal of the common-source transistor and outputs an output signal. A band-pass filter receives the output signal of the cascade-connected transistors. An adjustment circuit is interposed between the drain terminal and the gate terminal of the common-gate transistor, and adjusts the output impedance of the cascade-connected transistor.